Lemon Rx Microbrick User manual

Version 1.0 2021-07-23
Lemon Microbrick Reference Guide
Contents
Introduction..........................................................................................................................................2
Features............................................................................................................................................3
Applications for the Microbrick........................................................................................................3
Supply Voltage..................................................................................................................................4
Speed Controller and Failsafe ..........................................................................................................4
Basic Setups..........................................................................................................................................4
Connecting the Microbrick...................................................................................................................5
Setting Up the Microbrick ....................................................................................................................5
Specific Issues.....................................................................................................................................10
Rudder Steering..............................................................................................................................10
Throttle Features............................................................................................................................10
Indicator LEDs.................................................................................................................................11
Binding............................................................................................................................................11
Programming......................................................................................................................................11
Transmitter or Microbrick? ............................................................................................................11
Programming the Microbrick .........................................................................................................12
Swapping the Functions of the Onboard Servos........................................................................12
Changing Stabilization Response Direction................................................................................12
Selecting a Receiver Mix.............................................................................................................13
Enabling Dual Aileron Stabilization ............................................................................................14
Mixing Considerations....................................................................................................................14
Master Gain........................................................................................................................................16
Troubleshooting .................................................................................................................................16
ANNEX A: Tips, Tricks and Modifications ...........................................................................................18
The Variants of the Microbrick.......................................................................................................18
Adding an External Bind Function..................................................................................................18
Mounting the Microbrick with double sided tape. ........................................................................19
Power Supply Voltage and the Onboard Speed Controller............................................................19

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Introduction
The Lemon Microbrick is a small, lightweight, full range DSMP (DSMX™/DSM2™ compatible) five channel
receiver with two onboard rotary servos, 5A brushed speed controller, and optional 3-axis rate stabilization. It
weighs just under 7g and can run off a 1s or 2s LiPo. There are two JST-SH 1.00mm pitch connectors for external
servos and solder pads for the battery, brushed motor, and external brushless speed controller (ESC). It is well
suited to the under 250g range of outdoor foam models running on a 2s LiPo, as well as a wide range of indoor
“UMX” type planes that use the 1s, 150-220mAh size cells.
The Microbrick has five available flight channels in standard Spektrum order (1-4, 6), plus two internal control
channels:
Channel 1: Throttle: Onboard 5A brushed throttle and external signal for a brushless ESC
Channel 2: Aileron (or Right Aileron in dual servo aileron setups; optionally the onboard Rudder servo for 3
channels where Aileron stick is used for the Rudder)
Channel 3: Elevator onboard servo
Channel 4: Rudder onboard servo
Channel 5: On/Off control of stabilizer (internal to the receiver)
Channel 6: Aux1 (or Left Aileron in dual servo aileron setups)
Channel 8: Master gain control of stabilizer sensitivity (internal to the receiver)
Normally channel 5 is controlled by a two-position switch (A on a recent Spektrum transmitter) and channel 8 by
the rotary knob (or equivalent controls on OpenTX/ErSkyTX transmitters fitted with a DSM™ capable module).
Channels 2 and 6 servo outputs are available on two JST-SH 1.00mm 3 pin connectors. These are the same as the
ones used by the Spektrum™linear servo brick receivers and the HobbyKing HK5320S and HK5330S series rotary
1s servos (not the standard HK5320 and HK5330 which have very similar but incompatible Molex Picoblade
1.25mm connectors).
Channel 1 controls the onboard 5A brushed speed controller and the motor is connected to two solder pads or a
1.27mm Nano socket depending on the model of Microbrick. An additional two solder pads are provided for
connecting the battery. Alternatively, if header pins are installed, a brushless speed controller can be connected
with a 3-wire servo lead.
Setup as a 3 channel Setup as a 5 channel
(Battery and Motor connections not shown. A version with 5 pin vertical 0.1” header pins shown.)

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Features
The receiver has the following features.
•Small size. 32 x 27mm.
•Light weight. Less than7g.
•Full range (same high sensitivity as regular Lemon receivers)
•Large input voltage range. Usable with 1s→2s LiPo. Specified range 3.1→8.5v.
•Robust onboard micro rotary servos. 2s capable.
•Onboard 5A brushed speed controller (ESC) plus throttle signal for brushless ESC.
•Throttle safety on brushed controller (stick at low to enable motor).
•Integrated brushed LVC (Low Voltage Cut-off) for 1s. Motor starts pulsing at 3.2v.
•Integrated optional 3-axis rate stabilization with remote On/Off and master gain.
1
•Full onboard mixing for V-Tail, Delta (Elevon) and channel 2/4 swap. The last allows aileron stick control
of rudder steered models.
•Optional second stabilized aileron servo on channel 6 (Spektrum™ standard Dual Aileron setup).
Applications for the Microbrick
The Microbrick is ideal for small park flier models in the increasingly popular under-250g size. Often these
lightweight models have a wingspan of 700mm or less and are either Throttle/Rudder/Elevator only or in
addition have ailerons driven by two servos on a Y-lead or as two separate channels.
Another very obvious application is as a superior replacement for the popular Spektrum™ AR6400 style
integrated micro receiver with two onboard linear servos found in many UMX size micro models from E-Flite and
others. It is also attractive to scratch builders making the small 1s and 2s models that would normally use a linear
servo receiver.
The original Spektrum™ AR6400 (now discontinued) is shown below. There are several updated variants, with or
without stabilization, using 1s or 2s.
Spektrum AR6400, the classic micro brick
The Spektrum™ AR6400 style bricks range from tiny 3.5g,
3-channel versions used in the Micro Vapor to more
advanced 5 channel versions with AS3X™ rate stabilization
and customized SAFE™ self-levelling.
The Lemon Microbrick is not intended as a substitute for
the very lightweight (and limited) variants, nor does it
include SAFE™ type functionality, which needs to be
customized to each particular airframe. It will however
work well in the vast majority of “UMX” indoor and small
outdoor fixed wing aircraft.
It is particularly easy to substitute the Lemon in 3-channel
RET planes for an AR6400-type receiver, as it has an on-
board 5A capable brushed speed controller and the output arms of the two rotary servos match the control
directions of the AR6400 linear servos. Likewise, with a brushless motor and speed control, it can substitute for
the Spektrum brick in 2s UMX models such as the Turbo Timber.
1
Master gain requires a transmitter with at least eight channels.

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Supply Voltage
Warning: The Lemon Microbrick does not have reverse voltage protection.
Make sure the polarity of the supply is correct!
The Lemon Microbrick is specified to operate on a supply voltage of 3.1v
minimum to 8.5v maximum. In practice this means using a 1s →2s LiPo.
All of the onboard components (including the servos) are capable of this
voltage range. However, the two external white servo connectors carry the
full supply voltage and any servos connected to them MUST be capable of
tolerating this. For a 1s application this is not a concern. For a 2s supply
battery it is an issue if you use external servos. For example, you cannot
connect a Spektrum™ linear servo or a HobbyKing HK5320/5330 servo to the
Microbrick on 2s.
2
Speed Controller and Failsafe
With the onboard 5A brushed speed controller, if the Microbrick loses signal the servos will hold their last
position and after a second or so the brushed motor will stop running.
If you are using an external brushless speed controller (ESC), then be aware that on loss of signal the Microbrick
stops sending pulses to the ESC. The ESC then knows that the signal is lost, and the motor should stop with slight
delay. Not all small ESCs will do this, and you should test to be sure. For the small models for which this
Microbrick is intended, however, the risk is very small. Moreover, given the exceptional range of the receiver,
loss of signal is highly unlikely.
Basic Setups
Three Channel, Conventional Tail
Default control channels are: 1 = Throttle, 3 = Elevator, 4 = Rudder (TER).
However, you can also set up the Microbrick so that
default control channels are:
1 = Throttle, 2 = Rudder, 3 = Elevator (TRE).
This means that the Aileron stick controls the Rudder.
Many people prefer this for three-channel models. See
page 13 for instructions on how to do this.
Four Channel with Single Aileron Channel
For 4-channel models with single aileron channel, plug the
aileron servo or two servos on a Y-lead, into the right-
hand white 3 pin JST-SH 1.00mm connector (see photo at
right). Choose Normal Wing in the Spektrum Aircraft Type
menu.
2
The HobbyKing servos are rated to 4.8v but people have found that they work up to 5v satisfactorily. They can be
used in a 2s brushless setup where the speed controller has a 5v BEC supplying the Microbrick but must not be used
on a direct 2s (8.4v) supply. Lemon will be stocking a version of this servo under their own name.

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Five Channel with Dual Aileron Channels
For a 5-channel model with separate aileron channels, plug the Right aileron servo into the right-hand connector
(channel 2) and Left aileron servo into the left-hand connector (channel 6). Choose Dual Ail in the Spektrum
Aircraft Type menu.
Connecting the Microbrick
Motor/ESC/Battery connections can be soldered directly to the pads on the PC board to minimize weight. Lemon
supply the Microbrick in a variety of configurations, either with battery leads already installed and a Nano
1.27mm connector for brushed motors or with a 5-pin, 0.1” 90° header which is convenient for brushless
installations (the 5-pin 90° header variant is shown below).
With a Microbrick as delivered, using a default ACRO model on generation 2 or later Spektrum transmitter,
3
results in correct control directions for Throttle, Channel 5 (Mode) switch, and Channel 8 (Master Gain) knob.
That is, throttle stick up increases speed, switch (A) forward turns on stabilization, knob clockwise increases
Master Gain. The other channels are really arbitrary as far as direction goes. In other words, if you do not require
the stabilization function, it is ready to go out of the box. One tip: do not attach the servo arms until the receiver
is bound to the transmitter and working. Then it is possible to attach at 90° when sticks are neutral.
Setting Up the Microbrick
Here’s a step-by-step guide to preparing and flying the Microbrick.
These basic instructions assume you are using a recent Spektrum transmitter. If you are using an open-source
firmware transmitter, such as a Taranis or TX16s with OpenTX or ErSkyTX firmware, there is a separate
document entitled “Using the Microbrick with other Transmitters”.
3
DX6, DX6e, DX8G2, DX8e, DX9, DX18, NX6, NX8, NX10, iX12, etc.

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If you are using a transmitter with seven channels or less and thus do not have access to Master Gain (channel
8), stabilization will work normally but you will not have the ability to adjust stabilizer gain in flight. If you have
an eight or more channel transmitter, see “Master Gain” on page 16
It’s a good idea to set up the receiver and any external servos on the bench and test them before installing in the
model.
1. Set up the transmitter
If using a computer transmitter, set up a new ACRO model. Omit any elevon (delta) or V-tail mixing.
4
Make sure
control throws (end points/limits) are set to 100% (If using an open-source firmware transmitters, see the
separate “Using the Microbrick with other Transmitters” document).
2. Bind the receiver
The receiver needs to be bound to the transmitter before it will operate. The push button provides a convenient
and reliable method of binding. Hold the button in while connecting power. The red LED on the bottom of the
board will start flashing rapidly to indicate that the receiver is in bind mode. Release the button.
Now put the transmitter into bind mode and go through the bind procedure. If you have difficulty binding, move
the transmitter further away from the Microbrick. The sensitive receiver in the Microbrick can get overloaded at
close range, which may inhibit the bind process. Normally, the receiver will bind at 1-2m, but sometimes it needs
to be 3-4m from the transmitter. Nearby metal objects such as a furnace, fence or vehicle can also prevent
binding, as can a Wi-Fi router or nearby active RC transmitters.
After the receiver is bound, set the transmitter elevator and rudder sticks and trims to neutral. With the system
powered up, fit the two output arms as closely as possible to 90˚to the servo center line and attach with the
retaining screws.
3. Test the receiver on the bench in non-stabilized mode
Turn on the transmitter and then the receiver. Turn OFF stabilization. To do this, either:
•Turn all three of the on-board gain pots fully anticlockwise with a small screwdriver. This sets the
stabilization gains to essentially zero.
•OR ensure channel 5 is set to 100% (red and green LEDs both ON).
•OR set channel 8 (if available) to -150%.
Test all servos for smooth operation.
At this point, it’s a good idea to perform a range check to verify that the system is working properly.
4. Test the receiver in stabilized mode (if applicable)
Set the gain pots to mid-point (12 o’clock). Set the channel 5 switch to stabilization ON (-100%). Only the green
LED should be lit.
Briefly check that the red LED lights when you move the channel 5 switch to OFF (100%). Having both red and
green LEDs illuminated indicates that the stabilizer is NOT operating.
5
If you plan to use ailerons, plug a servo into the channel 2 connector, or two separate servos into the channel 2
and channel 6 connectors.
4
These mixes, if required, must be done in the Microbrick if stabilization is active.
5
If you wish to change the switch direction, reverse channel 5 in the transmitter.

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With stabilization ON, pots centered, and Master Gain (if available) also centred, move the receiver sharply in all
three axes (roll, pitch, yaw) and you should see each of the servos respond, even if only slightly. The channel 6
servo may not move until you have done the advanced configuration.
5. Mount the receiver in the plane
If you plan to use stabilization, install the Microbrick flat in the fuselage (right side up or inverted), aligned with
the centerline and with the pins/connector pads at either back or front. If not using stabilization, orientation is
not critical, as long as the onboard servos can drive the control surfaces.
The Microbrick, particularly in stabilized use, must be mounted firmly to the aircraft. It is important that the
receiver NOT be free to move as it will respond to any displacement as though that were a movement of the
plane. A shifting receiver will also cause unwanted movement of the control surfaces, even without stabilization,
as the control rods shift.
There are two holes in the circuit board intended to facilitate screwing the receiver to the airframe. Do not use
glue or double-sided tape for attachment unless you take precautions to protect the secondary circuit board on
the bottom. See Annex A for suggestions.
Ensure that the active portion of the antenna (the silver section about 31mm long) is well separated from any
substantial metal item like a LiPo battery or wiring. Take care not to kink the antenna.
Make sure you can access the three gain pots on the receiver, as you will need to adjust them, perhaps
repeatedly. Also, make sure the bind button is accessible.
6. Set up servos
Power on. If stabilization is enabled, use the channel 5 switch to turn the stabilizer OFF (both green and red LEDs
ON).
1. If you have not already done so, adjust transmitter reversing so that all servos work in the correct direction
in response to the sticks.
2. With trims in neutral, adjust servo arms and linkages to align your control surfaces. Use only a minimum of
sub trim on the transmitter for fine tuning. Servo arms should be at right angles to push rods to ensure equal
movement in both directions.
3. With end points (limits) and control rates at 100%, check that control surface throws are at the
recommended maximums for the model and adjust linkages if necessary.
Note when using stabilization: Adjusting throws in the transmitter does not affect stabilization servo reaction, so
throws need to be set mechanically to give the stabilizer an appropriate amount of control; the exact amount is
not critical, as gain will later be used to adjust stabilization response.
7. Set dual rates and expo in the transmitter
A good starting point for D/R is to set High Rate at 100% and Low Rate at 65-75% for each axis.
6
Set expo to suit.
Expo of 20-25% softens response around neutral and can make smooth flying easier.
Stabilization settings also affect the response of the model to the transmitter sticks, typically reducing sensitivity
with an expo-like effect. So, if you are using stabilization, you may want to adjust your rates and expo once you
find out how the model reacts.
Note that the dual rate and expo settings determine stick response but don’t affect how stabilization works. That
is entirely done within the receiver.
6
If using a DXs or similar basic Spektrum transmitter, the built-in D/R switch gives 100% and 75% rates.

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8. Test stabilization response and direction (if applicable)
Turn the three onboard gain adjustment pots fully clockwise (maximum).
7
Switch the stabilizer ON using the
channel5 switch (lights: green ON, red OFF). Sharply move the plane in each of the three flight axes and check
that the control surfaces move vigorously to oppose the disturbance. See diagram below.
The diagram shows how the surfaces should respond to movement of the model about each axis. When the
model is rolled sharply to the right, the right aileron should go down and the left aileron up to resist the
displacement. Likewise, when the model pitches nose-down, the elevator should go up to compensate. And
when it yaws nose-right, the rudder should go left.
Note that the control surfaces will only be displaced while the model is being disturbed; as soon as angular
motion stops, they will return to neutral. So, look for quick twitches of the control surfaces in the right
directions, not prolonged control offsets. If it is hard to see the movement, put your finger on the hinge line. It is
much easier to feel a small pulse than see it. To correct direction, change the appropriate channel as shown by
the blue LEDs: LED “A” (aileron), LED “E” (elevator) or LED “R” (rudder). Instructions for changing the response
direction are given on page 12.
THIS IS VITALLY IMPORTANT:
If stabilization moves the surfaces the wrong way (i.e., to increase the disturbance) your model may be
uncontrollable (until you switch off stabilization)!
Just as experienced RC pilots check stick directions before the first flight of the day, so a pilot using a stabilizer
should check that the surfaces move correctly in response to a disturbance.
9. Adjust the stabilizer gain pots (if applicable)
The direction of the screwdriver slot in the gain adjusting pots is described using the location of the
hour hand of an analog clockface. This one is approximately at “11 o’clock” for example. Clockwise
is in this direction ↻and anticlockwise this ↺.
The gain pots on the Microbrick can be adjusted from approximately 8 o’clock, which is fully anti-clockwise, to
approximately 4 o’clock, fully clockwise. The 8 o’clock position results in virtually zero stabilization gain
(effectively turning stabilization OFF) while the 4 o’clock position is maximum gain. Noon (12 o’clock)
corresponds to mid-range. The actual gain required depends on the type and design of the plane, as well as the
size of the control surfaces. It can only be found definitively by flight testing, but many models work well with
aileron around 10 o’clock, elevator about 12 o’clock and rudder at 2 o’clock or even higher.
7
If you are using channel 8 for Master Gain, set it to the middle of its range.

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Initially set the three gain pots at about the 10 o’clock position. This is a good conservative starting point that
will produce noticeable stabilization but probably not oscillation. For most models, at least one or two gain
settings will need to be increased or decreased during flight testing to achieve optimum stabilization. There is no
hard rule and gains can only be fine-tuned by observing the behavior of the model at various speeds during flight
testing.
10. Prepare for flying
Install the propeller and/or plug in the battery, as necessary. Check the control directions and stabilization
functions one more time. Do a reduced power range test using the range check function on the transmitter. This
should give at least 25m/27 yards range with full control.
Check that the channel 5 switch is operating correctly to turn stabilization ON (green light only) and OFF (green
and red lights). Make sure you know which way is OFF!
Test failsafe operation by running the model (well secured) at about half throttle and turning off the transmitter.
The motor should stop after a couple of seconds and the control surfaces should stay in their current positions.
If you have Master Gain on channel 8, set it to the middle of its range.
11. Perform a test flight
If stabilization is not used, proceed in the usual way to test and trim the model.
If stabilization is available, before taking off check that the stabilizer is turned OFF. Take off and fly around,
adjusting trim as necessary. Make sure the model flies properly without stabilization. If you need to make major
trim adjustments, you might want to land and make mechanical adjustments to the push rods.
At a safe height, use the channel 5 switch to turn the stabilizer ON. If the model rolls, dives or turns suddenly, at
least one of the gyro directions (as indicated by the three blue LEDs) is incorrectly set. Switch OFF the stabilizer
immediately! Land and fix. Likewise, if you encounter major oscillation, land and reduce gain in the axis/axes
involved. If Master Gain is available, you can just turn it down.
Assuming the model does nothing scary, continue flying to explore the action of the stabilizer. Do a shallow dive
to pick up speed and watch for oscillation on one or more axes. If it happens, just throttle back and slow down
(oscillation is quite different from control surface flutter and is generally not destructive).

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Notice how the model handles with the stabilizer turned on. It may be less responsive on one or more axes.
Experiment with dual rate settings. Turn stabilization off and on to get familiar with its effects.
12. Fine tune stabilizer gain (if applicable)
Now make a series of flights to optimize the individual gain settings. This will involve repeated landings to adjust
each pot on the receiver, followed by retesting in flight, but the basic job can be done relatively quickly.
8
It’s a
good idea to keep notes.
If you encountered oscillation on any axis during the initial flight, turn down the gain a little for that axis. Then go
through the following steps:
1. Increase the Rudder pot setting by about an “hour” (15°).
2. Take off with stabilization OFF. Turn ON at a safe height with the model in level flight. Watch for oscillation
on the yaw axis (“tail wag”). Do a shallow dive to pick up speed and again watch for oscillation.
3. Land and adjust the rudder pot as required. If there was no oscillation, even when diving, turn the pot up
another “hour” or so. If there was oscillation, turn the pot down.
4. Take off and retest. You’re aiming to set the pot fairly close to the gain that just produces oscillation in
normal flying.
5. When satisfied, go through the same procedure for the elevator pot.
6. Finally follow the same procedure to set the aileron gain pot.
Specific Issues
Rudder Steering
For a model steered by rudder that does not have ailerons, the above instructions still apply but there are two
options:
1. Set it up just like an aileron model as above but ignore all references to the Roll/Aileron channel. The aileron
stick will be inoperative, rudder is controlled by the rudder stick, and the model will correct for yaw in
stabilized mode with the rudder. For many stable models this will work well.
2. Apply the Aileron → Rudder mix (Rudder Steering) as described on page 14. In this case two things happen:
a. The Aileron stick now controls the on-board Rudder servo, AND
b. When the model is disturbed in roll the rudder is used to give an opposite yaw correction. The
aerodynamic setup of small models is normally well suited to this approach.
Throttle Features
Throttle Safety
To minimize chances of the motor starting accidentally, the throttle safety feature on the internal brushed ESC
requires that the throttle stick be at low before the throttle becomes active and the motor will run.
This issue is handled by the external ESC in a brushless setup.
Low Voltage Cutoff (LVC)
On a brushed 1s setup the motor will begin cutting in and out when the voltage drops to 3.2v. The actual motor
voltage at which this happens varies a little depending on the length and gauge of the battery wire because of
the voltage drop. In practice you will notice that the motor is pulsing at full throttle indicating the battery is
8
If you have an eight or more channel transmitter you can use Master Gain to help speed up the process of adjusting
the individual gains.

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dying. The plane is still controllable at reduced throttle without the pulsing effect. Land immediately, using low
power.
The behaviour of a brushless motor will depend on the speed controller used. Most brushless ESCs include an
LVC feature.
Indicator LEDs
Red/Green LEDS
These LEDS indicate the mode of operation. The green LED should always be on and indicates the receiver is
operating correctly. When lit, the red LED indicates that stabilization is inactive.
Green + Red
Stabilization OFF
Green only
Stabilization ON
Blue LEDS
The three blue LEDS, shown as “R”(Rudder), “E”(Elevator), and “A”(Aileron) in the picture on page5 serve
several functions:
1. To indicate the direction of the stabilizer response on each of the three axes.
2. To serve as indicators when setting the various mixes.
Lemon have packed a lot of functionality into the Microbrick and have achieved it by using only a single button
to do all of the input –but it comes at the cost of some possible confusion. The LED display listed in the Lemon
instructions is not always easy to follow or understand as lot of it is time dependent. It is easiest to understand
the green/red and blue LEDS if we consider it by intended function.
Binding
Start with the transmitter off or in System Setup mode so that it is not transmitting.
1. With the transmitter off, hold the button down and connect the battery. The Microbrick will quickly start
flashing the red LED on the bottom side rapidly. Release the button immediately –the red LED will continue
to flash.
2. Move the transmitter 1-2m away from the Microbrick and put it into Bind mode. The red LED on the
Microbrick should flash slowly a few times and then go solid. The Microbrick is now bound to your
transmitter. Most Spektrum transmitters will display the bind protocol which is normally “DSMX 22mS”.
3. Turn off the Microbrick and transmitter, then restart with the transmitter first.
The binding operation is normally a one-off task and does not have to be repeated unless you change
transmitters or move to a new model for that Microbrick within the transmitter.
Programming
Transmitter or Microbrick?
Where the mixing can or should be done depends on whether stabilization is enabled.
If stabilization is disabled
You have a choice. Either:
1. All mixing (including V-Tail and Elevon) can be carried out in the transmitter.
OR

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2. V-Tail or Elevon (Delta) mixing can be set in the Microbrick, while other mixing is done in the transmitter. For
example, the Microbrick could be set to V-Tail while aileron servos were on channels 2 and 6. In this case
Aircraft type would be set to Dual Ail or Flaperon in the transmitter.
Mixing in the transmitter has the obvious advantage of being familiar and flexible. It avoids the need to master
the “blue light dance” in the Microbrick. 
Mixing in the Microbrick, on the other hand, is very neat and self-contained. It only needs to be done once for a
given model.
If stabilization is enabled
Your options are restrained:
1. V-Tail or Elevon (Delta) mixing must be done only in the Microbrick; the transmitter must be set for a
NORMAL aircraft type.
2. For stabilization on both ailerons, Dual Aileron mixing must be set in the Microbrick, while the transmitter
must be set to Dual Ail wing type (or Flaperon).
3. Mixes that involve two functions on the same flight axis (such as Flap>Elevator or Throttle>Elevator) are
done in the transmitter as usual.
4. Rudder coupling (Aileron>Rudder mixing) is done in the transmitter as usual.
Programming the Microbrick
Swapping the Functions of the Onboard Servos
If the layout of your plane requires the Elevator and Rudder functions to be swapped between the onboard
servos, you can do this on the Microbrick. Essentially this action shifts the rudder servo to channel 3 and the
elevator servo to channel 4. Nothing else changes.
1. With the transmitter off, hold the receiver button down and connect the battery. The Microbrick will
immediately cause the red LED on the bottom side to flash rapidly.
2. Continue to HOLD the button until the “A” blue LED flashes (about 12 seconds). The red LED will continue to
flash but ignore it.
3. As soon as the “A” blue LED flashes, release the button. Within 3 seconds press it again to reverse the
servos. Lemon say that if the “A” LED is lit, this indicates servo swap. In practice, it can be a bit confusing, so
just check what happened by turning on the transmitter. If it didn’t work, do it again.
This operation is also normally a one-off task and does not have to be repeated, as the Microbrick remembers
the change permanently.
All of the following adjustments to the receiver are done with the transmitter ON, after
the Microbrick is bound and operating
Changing Stabilization Response Direction
This can be done for any of the 3 axes if the stabilizer correction direction needs to be changed to oppose an
external disturbance.
With the Microbrick on and operating:
Aileron (Roll) axis
Hold the button for just over 1 second. The first LED (“A”) will flash. Release the button and the other two will
start flashing for 5 seconds. During that time the aileron response can be reversed by pressing the button. The
direction will be indicated by the “A” LED. ON= reversed.

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Elevator (Pitch) axis
Hold the button for just over 3 seconds. The second LED (“E”) will flash. Release the button and the other two
will start flashing for 5 seconds. During that time the elevator response can be reversed by pressing the button.
The direction will be indicated by the “E” LED. ON= reversed.
Rudder (Yaw) axis
Hold the button for just over 5 seconds. The third LED (“R”) will flash. Release the button and the other two will
start flashing for 5 seconds. During that time, the rudder response can be reversed by pressing the button. The
direction will be indicated by the “R” LED. ON= reversed.
When done, just release the button and wait for normal operation to restore –the Microbrick will permanently
store the settings.
Selecting a Receiver Mix
There are four unique mixer modes that can be selected plus one additional dual aileron function.
To select one of the four unique mixes, hold the button for just over 10 seconds and all three blue LEDS will flash
simultaneously. Immediately release the button and one or two of the LEDs will be solid blue, indicating current
Mixer mode (see table below). To change the Mixer mode, within 5 seconds push the button briefly. Repeat as
necessary to step to the desired mix. When 5 seconds have elapsed with no button push the latest value is
stored and the receiver is ready to go. Mixer mode settings remain permanent until they are deliberately
changed.
LED
A
E
R
Mixer function
◉
None: Normal wing and tail
◉
V-Tail. Surfaces connect to onboard servos operated by (channels 3 and 4)
◉
Elevon/Delta. Surfaces connect to onboard servos (channels 2 and 3)
◉
◉
Channels 2 and 4 are swapped. Aileron stick operates rudder.
Explanation of Receiver Mixes
V-Tail
This arrangement is used to control both pitch (elevator) and yaw (rudder). The tail control surfaces move up or
down together for pitch and in opposite directions for yaw.
In the transmitter, Aircraft type is set to Normal wing. In the receiver, the blue “E” LED is ON during setup, thus
indicating on-board V-Tail mixing. The two onboard servos are connected to the two tail control surfaces and are
operated by channels 3 (Pitch function) and 4 (Yaw function).
An aileron servo can be plugged into the outer JST connector and can be operated by channel 2 for Roll. If the
Aircraft type is set to Dual Ail or Flaperon in the transmitter, the second white JST connector will operate a
second aileron servo (channel 6).
Elevon / Delta Wing
This arrangement is generally used for a tailless aircraft, such as a flying wing or delta, in which the wing control
surfaces (elevons) are used to control both pitch (elevator) and roll (aileron). The elevons move up or down
together for pitch and in opposite directions for roll.
In the transmitter Aircraft type is set to Normal wing. In the receiver, the blue “R” LED is ON during setup, thus
indicating on-board elevon mixing. The two onboard servos are connected to the two Elevons and are operated
by channels 2 (Roll function) and 3 (Pitch function).

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A rudder servo can be plugged into the outer JST connector, which is normally aileron, and can be operated by
channel 4 (Rudder). The other JST connector (ch6) just follows the onboard Rudder servo.
Aileron Stick > Rudder (Rudder Steering)
Referred to as “Legacy Mode” in the Lemon web page instructions, this mix moves the rudder servo to the
aileron stick (channel2). In the receiver, the “E” and “R” blue LEDs are ON during setup thus indicating A->R on-
board mixing.
This mix is helpful for a three-channel model: Throttle, Rudder, Elevator only. The Roll stick controls rudder while
the Pitch and Throttle are unchanged. If choosing this mix, do NOT use the outer white JST connector for a servo.
That connector (and the other as well if Dual Aileron is selected in the transmitter) will simply follow the rudder.
Enabling Dual Aileron Stabilization
Holding the button for just over 18 seconds causes the two furthest apart blue LEDs (“A” and “R”) to flash.
Quickly release the button.
LED
A
E
R
Mixer function
◉
◉
These two will be flashing
The display will change. If only the center LED “E” is flashing, then the Microbrick is in single aileron mode. If the
center LED is flashing and the outer two “A and R” are solid, then the Microbrick is in dual aileron mode.
You have less than 5 seconds to change aileron mode. Press briefly to swap between dual aileron and single
aileron. After changing mode, wait 5 seconds or so for the Microbrick to return to normal operation.
1. If single aileron is set, then the Microbrick actively stabilizes only on channel 2. Channel 6 can be used for an
independent function like flaps or gear. Normally a Y-lead or a single servo would be used for ailerons and
Normal must be set as the wing type in Spektrum transmitters.
2. If dual aileron is set, then the Microbrick actively stabilizes on both channels 2 and 6. Dual Ail (or Flaperon)
must be set as the wing/aircraft type in Spektrum transmitters. Normally separate aileron servos would be
plugged into the two white JST connectors.
Note that if you have single aileron setup on the Microbrick but set Dual Ail on the transmitter, with servos
plugged into both white JST connectors, then both ailerons will work but you will only get active stabilization on
the servo on channel 2.
General Hint: If you think you have done everything right, but the Microbrick does not seem to be responding
correctly after a configuration session, try turning the Microbrick and transmitter off, then on again. It is a small
computer after all, and this has been known to work. 
Mixing Considerations
The previous instructions should give you the information you need to set up V-Tail, elevon, dual aileron and
flaperon mixing with the Lemon Microbrick. The purpose of this section is to explain further how all this works.
The key point to understand is that the stabilizer only recognizes and corrects for movement in the three
standard flight axes. Consequently, the stabilizer expects the transmitter to provide the conventional “pure”
inputs: roll (aileron), pitch (elevator) and yaw (rudder). Any processing (mixing) needed to turn these inputs into
servo commands for a non-standard control arrangement such as elevon or V-tail has to take place in the
stabilizer itself, NOT in the transmitter. By contrast, flaperon mixing takes place in the transmitter.
What is Mixing?
In a simple control setup, each axis has a dedicated control surface (or pair of surfaces in the case of aileron).
Each axis is controlled by a separate channel passed from the transmitter through the receiver (and its

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integrated stabilizer) and on to the servo that moves the control surface. For the Lemon receivers, channels 2, 3
and 4 are used, respectively, for the three basic controls, aileron, elevator, and rudder.
Mixing is the process of combining transmitter inputs to provide the servo output(s) required for control. For
many purposes, the mixing is done in the transmitter. For example, throttle can be mixed to elevator so that as
power is increased, a small amount of down is added to the elevator signal in order to counter the model’s
tendency to climb. Another common mix couples aileron with a small amount of rudder to aid in coordinating
turns. The important thing about such mixes for our purposes is that they don’t affect the basic arrangement of
allocating one channel to each control axis or function. Consequently, they still provide the separate inputs
required by the stabilizer.
The V-Tail and Elevon mixes we are concerned with are different in that they involve two separate and
independently driven control surfaces working together to provide a single aerodynamic function. For example,
a pair of elevons must work in unison to produce pitch and in opposition to generate roll. To achieve this, the
mixing MUST be done on board, since the stabilizer cannot interpret inputs in the form of “mixed” control
commands; it only understands roll, pitch, and yaw. Any V-Tail or Elevon mixing in the transmitter must therefore
be disabled. Having such mixing enabled in the transmitter when stabilization is active (or having it enabled in
both transmitter and receiver) has been the source of a great deal of confusion for many pilots (and some
accidents).
Flaperon is another case where two inputs (aileron and flap) are involved, but here the mixing is done in the
transmitter.
Let’s take a look specifically at how these three types of control setup are dealt with in relation to the Lemon
Microbrick. The actual setting of the mix and the indication of what has been set by the 3 blue LEDs has been
described above.
V-Tail
In this arrangement, the functions of elevator and rudder are managed by tail control surfaces that move up or
down together for pitch, right or left together for yaw.
In the transmitter tail type (if available) is set to Normal; this ensures that separate (not mixed) elevator and
rudder signals are sent to the stabilizer. In the receiver, the second blue LED is on during setup thus indicating
on-board mixing. The two onboard servos are operated by transmitter channels 3 (Elevator function) and 4
(Rudder function.
Elevon / Delta Wing
This arrangement is generally used for a tailless aircraft, such as a flying wing or delta, in which the wing control
surfaces (elevons) are used to control both pitch (elevator) and roll (aileron). The elevons move up or down
together for pitch and in opposite directions for roll. In the transmitter wing type is set to Normal. In the
receiver, the third blue LED is on during setup thus indicating on-board mixing. The two onboard servos are
operated by channels 2 (Roll function) 3 (Elevator function).
Flaperons (dual aileron channels)
The flaperon arrangement enables the ailerons not only to move in the usual opposite directions to produce roll,
but also to move together downward to produce flap action (and possibly upward to produce spoiler action),
thus controlling lift and drag.
This dual function capability requires that each aileron servo have its own channel: normally channel 2 for right
aileron (RAL) and channel 6 for left aileron (LAL). The stabilizer passes the control inputs sent by the transmitter
through to the two aileron channels. The inputs can include not only flaperon mixing but also differential aileron

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(more up than down to compensate for adverse aileron drag). Unlike V-Tail and Elevon, where the mixing
happens in the stabilizer, aileron/flaperon mixing takes place in the transmitter.
For the stabilizer to fully apply corrections to both ailerons in response to wind gusts, etc., stabilization of
channel 6 must be ON. If it is OFF, only the right aileron (CH2) will have stabilizer action.
In the transmitter, wing type should be set to Dual Aileron or Flaperon, as appropriate. If flaperon is used, then
Flap mixing must be applied in the transmitter; this usually includes mixing to the elevator channel to
compensate for the pitch effects of flap action. Also, differential aileron can be applied if required.
In the receiver, the right and left aileron servos are plugged into the white JST-SH connectors for channels 2 and
6 respectively.
Reversing Controls and Corrections
The direction of response of the control surfaces to the transmitter inputs must be checked and corrected, if
necessary, AFTER any mixing is set up for V-Tail, Elevons and Flaperons. To avoid distracting control surface
motions, stabilizer action should be turned OFF with the channel 5 switch during this process (mixing occurs
whether the stabilizer is on or off).
When all control settings and mixing are completed, and the control directions are correct, the direction of the
stabilizer’s response to a flight disturbance must be set for each axis. Checking must be done with the stabilizer
turned ON and in accordance with the instructions provided earlier. To change the direction of response for an
axis, use the push button switch and blue LEDs as previously indicated.
Master Gain
Master Gain multiplies the three individual gain values set by the three gain pots by a constant factor. It is set by
the value of channel 8 and so is unavailable on transmitters with fewer channels. When channel 8 is at -100% the
multiplier is close to 0 and when at +100% it is close to 2x. At the midpoint (0%), the multiplier is 1x. Turning the
master gain down reduces the effect of all three set gains, while turning it up increases the gain. If the
transmitter has seven channels or less, Master Gain defaults to 1x and so has no effect.
Note that -100% on channel 8 is not exactly a master gain of zero; you may still see some very small stabilization
effect. If you want to completely eliminate stabilization, set the low value to -150% in the channel 8 servo travel
setting.
If you have Master Gain available, you can greatly speed up the process of setting individual gains. In the air,
advance the channel 8 (Aux3) control gradually until you observe oscillation on an axis. Note which axis is
involved, land and turn down the gain on the corresponding pot. Repeat until all three axes are set so that with
the Master Gain at midpoint, there is no oscillation. Turning up Master Gain to 2 or 3 o’clock should start to
show signs of oscillation.
Troubleshooting
Receiver Won’t Bind
The Microbrick is a sensitive receiver; it can get overloaded during the bind process if it is too close to the
transmitter or experiences multipath reception. Experience has shown that nearly all bind problems can be
solved by ensuring that the transmitter and receiver far enough apart and are not close to large metallic
surfaces. Generally, 1 to 2 metres/yards is far enough, but sometimes separation of several metres/yards is
needed.

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Even this may not be enough if you are in a place that has a high level of 2.4Ghz radio frequency transmissions,
such as near a powerful Wi-Fi network or router. Also, avoid metal tabletops, fences, vehicles, etc. In such
situations, try moving to a different location.
Red /Green LEDs Don’t Change
If the red/green LEDs do not change from Green only to Red-and-Green when the channel 5 switch is moved,
then the Microbrick is not receiving the correct control signal on channel 5.
Check that you have assigned a switch to channel 5.
Check on the Monitor screen that channel 5 is moving from -100% to +100% when the switch moves from one
side to the other. If not, you may have to adjust servo travel on channel 5.
The stabilizer is ON between -100% and 0% and OFF between 0% and 100%. If you have assigned a two-position
switch (A, H) to channel 5, the stabilizer will by default be OFF in position 0 and ON in position 1. This can be
reversed by reversing servo channel 5.
If you have assigned a three-position switch to channel 5, the stabilizer will by default be OFF in position 0 and
ON in position 2, but there may be ambiguity in the center (position 1). Use Digital Switch Setup to shift the
value of position 1 one way or the other. For transmitters without Digital Switch Setup, adjust the Subtrim of
channel 5 a few percent from 0%. The aim is to ensure that the center position is either definitely OFF or
definitely ON. Your choice.

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ANNEX A: Tips, Tricks and Modifications
Some stuff that may be useful.
The Variants of the Microbrick.
Lemon sell four different variants of the Microbrick. Here they are in the likely order of popularity:
LM0070M1.
Has a Molex Picoblade 1.27mm pitch 2 pin battery lead and a 3 pin (only two are used) Nano 1.27mm round pin
motor connector. The battery lead and Nano connector are the same as those found on the vast majority of
UMX type models that have the Spektrum AR6400 brick receiver with onboard linear servos. The white JST-SH
connectors on the Microbrick are the same as the AR6400 as well. Basically, this is a drop-in replacement for the
extremely popular Spektrum linear servo bricks. The outer servo arms even move the same way as the linear
bricks and a UMX brushed gearbox motor plugs straight into the two left sockets of the Nano connector.
LM0070H.
Has a 5pin 0.1” header soldered to the PC pads. This one has two main applications.
It is the obvious choice for 2s applications which will normally have a speed controller to run a brushless motor.
The throttle lead from the speed controller plugs on to the 3 right hand pins and also supplies power to the brick
and any external servos from its BEC. The two left hand pins are ignored.
It is the “general purpose” version. You can solder anything you require to the 5 pins easily. People seeking
minimum weight can remove the header pins and solder directly to the PC board pads. Hint: Cut the plastic
header spacer between each pin and remove them one at a time.
LM0070M2.
This one is identical to the LM0070M1 except it has a Molex 2.00mm pitch 51005/6-0200 connector. This is
commonly called a Losi or Walkera connector, and comes on many 1s or 2s quad LiPo batteries –but check the
polarity carefully as the Losi and Walkera versions are different and the Microbrick is not protected against
reverse polarity! It is intended for 1 or 2s brushed applications with those batteries.
LM0070JST.
This one is identical to the LM0070M1 except it has a JST-RCY 2.50mm pitch connector. This is the well-known
but old “JST Red” connector, and also comes on many 1s or 2s LiPo batteries. It is intended for 1 or 2s brushed
applications with those batteries.
NOTE: Although the Nano connector on the LM0070M1, LM0070M2, and LM0070JST has three sockets it is NOT
suitable for connection of a brushless motor. There is no onboard brushless speed controller on the Lemon
Microbrick.
Adding an External Bind Function.
The Lemon Microbrick has a Bind Button on the PC board.
This has two significant advantages:
1. It cannot be lost like a Bind Plug. And it is smaller and lighter than a bind pin connector which matters on
this micro receiver.
2. It’s much more reliable than the Autobind function found on many of the 1s micro receivers such as the
Spektrum™ AR6400 UMX bricks. Anyone who has tried to rebind one of those in an indoor stadium
swamped by Wi-Fi 2.4GHz signals will appreciate that.

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BUT: It has one disadvantage. You need to have access to the button while binding. Normally this is not a big
problem as if you use stabilization you need access to the 3 gain pots and the bind button is right next door.
However, if the Microbrick is buried in the plane it can be a real problem.
SOLUTION
Add an external Bind Button or 0.1” header pins for a regular Bind Plug. If you find it
awkward to hold the tiny bind button while plugging in the battery at the same time,
then header pins and the regular bind plug may be more convenient.
All you have to do is solder two fine wires to these two pads on the Microbrick.
Put a small momentary switch or a 0.1” pin header (for connecting a Bind Plug) on the
other end. Either will be in parallel with the onboard switch and will initiate binding.
Put the switch or header somewhere convenient on the model. A long shaft PCB board
switch as shown is particularly convenient as you can feed it through a hole in the
fuselage and hot glue (or similar) the switch in place.
Mounting the Microbrick with double sided tape.
Lemon specifically warns against any form of mounting that stresses the
underside of the PC board.
What’s the problem? The RF daughterboard that is actually the receiver is
mounted to the bottom of the main PC board by only four solder pads. This
is perfectly adequate for a unit that is protected in a case, but to save
weight the Microbrick is not so protected. If you mount the Microbrick using double sided tape, there is a very
good chance that you will rip the daughterboard off if you try and remove
it from the model. Lemon intends you to mount the Microbrick on rails
using the two screw holes provided but that may not be convenient; you
may want to use the traditional double-sided tape common in micro
planes.
Here is what to do.
Run some hot glue from a narrow tip glue gun around the board as shown
in the picture.
It is easiest to use one of the small hot glue guns with a fine tip sold for craft use. If you hit the hot glue with a
heat gun after it is in place it will melt again and run in between the two boards and make a strong joint.
This will add very little to the total weight but will solidly anchor the daughterboard on 3½ sides to the main PC
board. You can then use double sided tape as usual. You might want to use two or more layers in parts to “level”
that attachment surface. If you are absolutely sure you will never need to resolder to the five connection pads,
you can hot glue all four sides.
Power Supply Voltage and the Onboard Speed Controller
The Microbrick is 1-2s capable. That means you can power it from a 1s LiPo, a 5v or 6v BEC in an external
brushless speed controller, or direct from a 2s LiPo. All onboard components including the two servos and the
brushed speed controller are good up to 2s (8.5v) supply.

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BUT some cautions:
1. The onboard brushed speed controller must be limited to 5A regardless of the supply voltage.
2. Any servos connected to the two white JST-SH Aileron/Aux1 connectors must be capable of operating on
the full supply voltage.
In practice there are three likely scenarios:
1. Supply is a 1s LiPo cell (typically 70-300mAh capacity) and that is the maximum voltage in the system.
Typically, the motor is a 1s geared brushed motor running direct from the two brushed connectors on
the Microbrick. All components will see a maximum of 4.2v. External 1.7/1.9g servos of the 5320/5330
type and linear servos intended for 1s AR6400 type bricks work fine.
2. Supply is from an external brushless speed controller. Typically, the motor is a 2s version, and the 2s LiPo
speed controller supplies the Microbrick with 5v from its BEC. In this case the External 1.7/1.9g servos of
the 5320/5330 type are just outside their 4.8V maximum rating but many people use them on 5v without
an issue. You cannot use linear 1s servos on 5v, however.
3. Supply is direct from a 2s LiPo to the Microbrick. This might typically be used on a DLG or a plane with a
2s brushed motor. In this case any external servos, if used, must be 8.4V capable. The onboard
Microbrick servos are fine on 2s.
MB Ref Guide v1.0.1g