eastern microBrute User manual

microBrute Modulator
May 2010, Rev 1 − 1 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
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microBrute Modulator
May 2010, Rev 1 − 2 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
Introduction to the microBrute Modulator
Thank you for purchasing the microBrute Modulator / Interrupter Kit. The microBrute
Modulator is a handheld controller (interrupter) that was specifically designed for use
with the microBrute DRSSTC system. It features two potentiometers which the user can
adjust in real time to control both the pulsewidth as well as the pulse repetition frequency
(PRF) of the modulation (pulsing).
The microBrute Modulator can also be modified by the user to utilize different ranges of
pulsewidths and PRFs to suit most any SSTC or DRSSTC system.
Notice to Beginners: If you are first time kit builder, you may find this instruction
manual easier to understand than expected. Each component in this kit has an individual
check box, while a detailed description of each component is provided as well. If you
follow each step in the instruction manual in order, and practice good soldering and kit
building skills, the kit is next to fail-safe.
Please read this manual in its entirety before building, testing, or operating your kit!
Circuit Description
The microBrute Modulator utilize two 555 Timer ICs to perform the pulse timing logic.
555 Timer, U1, runs in astable (continuous) mode, providing the PRF, of the modulation,
while 555 Timer, U2, is configured as a monostable (single pulse) one-shot. U1 produces
a continuous series of pulses, whose frequency is determined by the RC network
comprised of C2, R2, and R3, and is adjustable by the user by varying potentiometer R3.
The frequency of these pulses equate to the pulse repetition frequency (PRF) of the
interrupter. Each of these pulses then triggers U2 to produce a one-shot pulse of some
varying pulsewidth, which is determined by the RC network comprised of C7, R6, and
R5. The pulsewidth of this one-shot can be varied by the user by adjusting
potentiometer, R5. The figure on the next page shows the output timing of the
modulator.
When operating the microBrute DRSSTC, power output is controlled by varying the
pulsewidth, or R5. When pulsewidth is equal to “0”, the DRSSTC is in an OFF state.
When pulsewidth is increased, the DRSSTC output power is gradually increased.

microBrute Modulator
May 2010, Rev 1 − 3 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
Kit Building Tips
A good soldering technique is key! Let your soldering iron tip gently heat both the wires
and pads simultaneously. Apply solder to the wire and the pad when the pad is hot
enough to melt the solder. The finished joint should appear like a small shiny drop of
water on paper, somewhat soaked in. If the pads have not heated up sufficiently, melted
solder (heated only by the soldering iron itself) will form a cold solder joint and will not
conduct. These cold joints appear as dull beads of solder, and can be easily fixed by
applying additional heat to the pad and wire. All components, unless otherwise noted,
should be mounted on the top side of the board. This is the side with the silkscreen
printing.
When installing components, the component is placed flat to the board and the leads are
bent on the backside of the board to prevent the part from falling out before soldering.
The part is then soldered securely to the board, and the remaining lead length is clipped
off. It is also extremely important to place the components as close to the board as
possible. This is necessary for proper operation over the wide frequency range of the
various kits we provide. Also be sure that component lead lengths are always as short as
possible. This will avoid adding any stray capacitances or inductances that can be
detrimental to circuit operation.
An alternative approach (which is actually the one I use) is to install the component into
the board and then apply a piece of masking tape on the topside to the hold the
component in temporarily. The leads on the backside of the board are then trimmed
leaving about 0.10” lead protruding through the backside of the board, and then soldering
from the backside. You can then remove the masking tape, apply a small amount of
solder on the top to complete the joint.

microBrute Modulator
May 2010, Rev 1 − 4 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
microBrute Modulator Parts List
RESISTORS
1 1.5k Resistor (brown-green-red), R1
1 51k Resistor (green-brown-orange), R2
1 1k Resistor (brown-black-red), R4
1 100k Resistor (brown-black-yellow), R7
1 100k Panel Mount Potentiometer, R3
1 10k Panel Mount Potentiometer, R5
CAPACITORS
3 0.1uF Capacitor, C1,C2,C5
1 0.015uF Capacitor, C7
3 0.01uF Capacitor, C3,C4,C6
DIODES
1 Diode, 1N4002, CR1
1 LED (red or green), Panel Mount, D1
INTEGRATED CIRCUITS (ICs)
2 555 Timer, U1,U2
MISCELLANEOUS
1 Connector, RCA, Female, J1
1 Plastic Enclosure
1 9V Battery Connector, BAT1
1 Panel Switch, ON-OFF, SW1
2 Knob, 1/8” Shaft
1 Front Panel Plate
1 Misc. Hardware
1 Misc. Hook-up Wire
REQUIRED, NOT SUPPLIED
1 9V Battery

microBrute Modulator
May 2010, Rev 1 − 5 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
microBrute Modulator Component Layout Diagram

microBrute Modulator
May 2010, Rev 1 − 6 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
KIT Building Instructions
Now we will begin building the kit. There are just a few more important things to know
before we install the first components.
For each component, the word “install” always means the following:
1. Pick the correct value to start with.
2. Insert the component into the correct printed circuit board (PCB) location.
3. Orient the component correctly – especially when there is a right and a wrong
way to solder it in. (i.e. Electrolytic capacitors, diodes, ICs, transistors, etc…)
4. Solder all connections unless directed otherwise. Ensure enough heat is used to
allow solder to flow for clean, shiny, and completed connections.
Also, please be sure to take us seriously when we say that good soldering is the key to the
proper operation of your circuit!
•Use a 25W soldering pencil with a clean, sharp tip. DO NOT USE a high power
soldering gun such as those trigger activated units.
•Use only rosin core solder intended for electronics use
•Ensure your work area is clean, and has plenty of bright lighting
•Build your kit in stages, taking breaks to check your work. Be sure to clean the
board periodically with a brush or compressed air to remove any excess wire
cuttings, etc…
Okay, so lets begin!
1. Install R1, 1.5k resistor (brown-green-red)
2. Install R2, 51k resistor (green-brown-orange)
3. Install R4, 1k resistor (brown-black-red)
4. Install a jumper (short) in the R6 location. You can use the excess lead that
you cut off from another resistor to do this.
5. Install R7, 100k resistor (brown-black-yellow)
6. Install CR1, 1N4002 diode. The cathode band on the diode must match that
shown on the silkscreen.
7. Install C1, 0.1uF capacitor (marking BC104)

microBrute Modulator
May 2010, Rev 1 − 7 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
8. Install C2, 0.1uF capacitor (marking BC104)
9. Install C5, 0.1uF capacitor (marking BC104)
10. Install C3, 0.01uF capacitor (marking BC103)
11. Install C4, 0.01uF capacitor (marking BC103)
12. Install C6, 0.01uF capacitor (marking BC103)
13. Install C7, 0.015uF capacitor (marking BC153)
14. Add a jumper (short) from U3, Pin 1 to U3, Pin 4.
15. Install U1, 555 Timer. The 555 Timer IC may be soldered directly to the
PCB without worry, but you may use an 8-pin DIP socket (your own) if you
prefer. Use the same care in soldering such a socket and inserting the IC as you
would in direct soldering of the chip. Note that one end of the IC is marked by a
dot, notch, or band; this end MUST be oriented as shown on the PCB layout.
16. Install U2, 555 Timer. The 555 Timer IC may be soldered directly to the
PCB without worry, but you may use an 8-pin DIP socket (your own) if you
prefer. Use the same care in soldering such a socket and inserting the IC as you
would in direct soldering of the chip. Note that one end of the IC is marked by a
dot, notch, or band; this end MUST be oriented as shown on the PCB layout.
17. Solder approx. 3-4" of wire lead to each of the following locations on the
PCB board:
a. J1+
b. J1-
c. +9V
d. R3+
e. R3-
f. R5+
g. R5-
18. Using a utility knife or scroll saw, cut out a rectangular hole as shown in the
figure below. EXTREMELY IMPORTANT - First line up the both the top and
bottom piece of the enclosure and fit together. You want to ensure to cut the right
end of the top piece of the enclosure as there are two stand-offs which will
interfere with the battery compartment if you cut the wrong end of the top piece
of the enclosure.

microBrute Modulator
May 2010, Rev 1 − 8 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
19. Using a 1/4" Drillbit, drill a hole approximately 2/3rd across the top of the
end of the top piece of the enclosure, as shown in the figure below, for the RCA
connector, J1. Be sure not to drill in a location that will interfere with the internal
stand-off.
20. First, use rubbing alcohol to clean the top surface of the enclosure where the
control plate will be installed. Next, carefully peel away the adhesive backing on
the control plate, position it, and then press firmly to stick it in place. Apply lots
of pressure over all areas of the control plate to ensure good contact with the
enclosure surface.

microBrute Modulator
May 2010, Rev 1 − 9 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual
21. First, using a multimeter, determine which switch position of the switch is the
ON position. This ON position will be the top of the switch. Press fit SW1, ON-
OFF rocker switch into the front control plate cut-out. The ON position will be
pointing up.
22. Press fit D1, panel mount LED into the front control panel hole. This hole is
directly to the right of the rocker switch. If the LED is loose, you may use epoxy
(not supplied) or a similar adhesive to secure it in place.
23. Install R3, 100k potentiometer, into the RIGHTMOST front control plate
potentiometer location. Secure in place using the included lock washer and nut.
Be sure not to overtighten the nut as you may damage the potentiometer.
24. Install R5, 10k potentiometer, into the LEFTMOST front control plate
potentiometer location. Secure in place using the included lock washer and nut.
Be sure not to overtighten the nut as you may damage the potentiometer.
25. Connect BAT1 and SW1 to the PC board as shown in the figure below. Be
sure to ensure proper polarity during connection, or you may damage the active
components such as U1 and U2.
26. Connect D1 to the PC board as shown in the figure below. The black lead of
the panel mount LED should be connected to the pad of D1 designated with a "K"
as this is the cathode.
27. Connect R3, 100k potentiometer, to the PC board as shown in the figure
below. Be sure to connect the wires to the potentiometer pins EXACTLY as
shown in the figure below to ensure that the PRF adjusts in the correct direction
when turning the potentiometer. This is VERY important.
28. Connect R5, 10k potentiometer, to the PC board as shown in the figure
below. Be sure to connect the wires to the potentiometer pins EXACTLY as
shown in the figure below to ensure that the PW adjusts in the correct direction
when turning the potentiometer. This is VERY important.
29. Connect J1 to the PC board as shown in the figure below. The center lead of
the connector should connect to the pad marked “+” on the PC board.

microBrute Modulator
May 2010, Rev 1 − 10 − © 2010 Eastern Voltage Research, LLC
microBrute Modulator Instruction Manual