AkitikA GT100 User manual

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GT100
TWO CHANNEL
AUDIO POWER AMPLIFIER
ASSEMBLY MANUAL
© 2012 AkitikA, LLC
All rights reserved
Revision 1p30 June 24, 2012

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Table of Contents
able of Contents................................................................................................................ 2
able of Figures .................................................................................................................. 3
Section 1: About his Manual ............................................................................................ 4
Who Should Attempt this Project? ................................................................................. 4
ools You’ll Need........................................................................................................... 4
Project Overview ............................................................................................................ 4
Important Safety Notes ................................................................................................... 5
About Components ......................................................................................................... 5
Section 2: Building the Power Supply PCB ....................................................................... 6
Component Order............................................................................................................ 6
Install the Resistors ......................................................................................................... 6
Install the Diodes ............................................................................................................ 8
Identifying the glass body diodes ............................................................................... 9
Install the Small Capacitors .......................................................................................... 10
Install the ransistors.................................................................................................... 11
Install the Integrated Circuits........................................................................................ 11
Install the Big Capacitors.............................................................................................. 12
Final Inspection of the Circuit Board............................................................................ 12
Power Supply Final Assembly...................................................................................... 12
Attach the Power Supply Ground Wire ........................................................................ 14
Section 3: Assembling the Amplifier Circuit Boards ....................................................... 15
Install the Resistors ....................................................................................................... 15
Install the Small Capacitors and the Diodes ................................................................. 17
Last Capacitors and the ransistors .............................................................................. 18
Winding the Output Inductor ........................................................................................ 19
Final Inspection of the Circuit Board............................................................................ 20
Installing the LM3866 and Mounting the Amplifier Board to the Heat Sink............... 21
Attach the Amplifier Module Wires ............................................................................. 23
Attaching LEF Module Power Wires ..................................................................... 23
Attaching RIGH Module Power Wires .................................................................. 24
Section 4: Wiring it All ogether ..................................................................................... 25
Input Connectors........................................................................................................... 25
Speaker Binding Posts .................................................................................................. 26
Power Wiring ................................................................................................................ 26
ransformer Installation............................................................................................ 28
esting the Power Supply ............................................................................................. 30
Final Amplifier Wiring ................................................................................................. 31
Installing Amplifier Modules into the Chassis ......................................................... 31
Wiring Amplifier Power ........................................................................................... 33
Fasten the Power Supply to the Chassis ................................................................... 33
Wiring Input Connections......................................................................................... 34
Wiring Speaker Connections .................................................................................... 34
Completing Ground Connections ............................................................................. 34
Visual Inspection ...................................................................................................... 35

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Install the op ........................................................................................................... 36
Section 5: esting It Out ................................................................................................... 36
Section 6: Specifications and Schematics......................................................................... 36
Appendix 1 - Resistor Color Code................................................................................ 41
Appendix 2 - Preparing a Shielded Cable End ............................................................. 42
Table of Figures
Figure 1-Installing resistors ................................................................................................ 6
Figure 2-Form the cathodes of D4-D7 as shown (banded end denotes cathode) ............... 8
Figure 3-Black text shows C2 polarity, yellow plus sign shows C3 polarity................... 10
Figure 4-Pinout of U1, viewed from the top..................................................................... 11
Figure 5-Completed Power Supply Circuit Board awaiting Q5 installation .................... 12
Figure 6-Note the rounded brackets used for the power supply heatsink and PCB ......... 13
Figure 7-Placing thermal compound on Q5...................................................................... 13
Figure 8-Installing Q5 on the heatsink and to the PCB .................................................... 14
Figure 9-Remember to solder Q5's leads .......................................................................... 14
Figure 10-power supply with attached ground wire ......................................................... 14
Figure 11-First four resistors are installed, leads bent on the back side, but not yet
soldered. ............................................................................................................................ 15
Figure 12-leads soldered and clipped ............................................................................... 16
Figure 13-showing LED cathode orientation.................................................................... 18
Figure 14-Starting to wind the output inductor................................................................. 20
Figure 15-finishing step for the output inductor ............................................................... 20
Figure 16-Mounting assembled PCB to heat sink ............................................................ 21
Figure 17-mounting the PCB to the heat sink................................................................... 22
Figure 18-solder the LM3886 pins ................................................................................... 22
Figure 19-a completed amplifier module.......................................................................... 23
Figure 20-shielded cable for left channel.......................................................................... 24
Figure 21-installing the RCA jacks................................................................................... 25
Figure 22-positioning the RCA input jacks and ground lug............................................. 26
Figure 23-Wiring IEC power connector ........................................................................... 27
Figure 24-Power wiring with IEC connector installed into chassis.................................. 27
Figure 25-Installing power wires on the switch................................................................ 28
Figure 26-joining the secondaries..................................................................................... 29
Figure 27- oroidal ransformer Mounting ...................................................................... 29
Figure 28-connecting up the power transformer............................................................... 30
Figure 29-cable tie the red and orange wires as shown .................................................... 30
Figure 30-spread thermal compound on the 3/8" wide ridge............................................ 32
Figure 31-amps installed, wiring not complete................................................................. 32
Figure 32-I/O Wiring detail (one channel) ....................................................................... 33
Figure 33-Grounding Stud Detail ..................................................................................... 35
Figure 34-Power Supply Schematic.................................................................................. 38
Figure 35-Amplifier Module Schematic........................................................................... 39
Figure 36-Overall Wiring ................................................................................................. 40
Figure 37-demonstrating the resistor color code .............................................................. 41
Figure 38-shielded cable end, as of step 4 ........................................................................ 44

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Figure 39-Shield wired end prep completed..................................................................... 44
Section 1: About This Manual
his manual gives the information you need to build Akitika LLC’s G 100 Stereo Power
Amplifier.
Who Should Attempt this Project?
You can build this kit if you can:
1. solder (using normal rosin core solder and a soldering iron).
2. use simple hand tools like screwdrivers, wire cutters, and pliers.
3. read and follow directions.
It helps if you:
1. know a bit about electronics, or
2. have a friend who knows a bit about electronics
3. can get to You ube to watch a few helpful videos about the assembly process (not
available as of this version of the manual)
Tools You’ll Need
You’ll need the following tools:
1. flat blade screwdriver for #6 screws
2. Phillips screwdriver (#2)
3. pliers or nut drivers suitable for #6 hardware (5/16” nut driver or hex wrench)
4. needle nose pliers (helpful, but not strictly necessary)
5. pencil type soldering iron of 25 to 50 Watts (no huge honking soldering guns or
blowtorches)
6. wire cutters and strippers
7. multi-meter (helpful, but not strictly necessary)
8. magnifying glass, if you’re over 42!
Project Overview
he project consists of the following steps:
1. Build the Power Supply Regulator Board
2. Build left and right channel amplifier circuit boards.
3. Install and wire the circuit boards, switches, and connectors into the chassis.

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Important Safet Notes
By purchasing, using, or assembling this kit, you have agreed to hold AkitikA, LLC
harmless for any injuries you may receive in its assembly and/or use. o prevent injuries:
• Wear safety glasses when soldering to prevent eye injuries.
• Always unplug the power before working on the amplifier.
• Large capacitors hold lots of energy for a long time. Before you put your hands
into the amplifier:
o Pull the AC plug!
o Wait 1 full minute for the capacitors to discharge!
• Remove jewelry and rings from your hands and wrists, or anything that might
dangle into the amplifier.
• If working in the amplifier, keep one hand in your pocket, especially if you’re
near the power supply or power supply wires. his can prevent serious shocks.
• Build with a buddy nearby. If you’ve ignored all the previous advice, they can
dial 911 or get you to the hospital.
About Components
We reserve the right to make design/or component changes at any time without prior
notification.

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Section 2: Building the Power Supply PCB
his section details the process of building the circuit board. We start with an overview
on this page. he specifics you need to start building begin on the next page.
In general, you’ll start with the components that lay closest to the board, working your
way towards the taller components. You will:
1. Install the resistors
2. Install the diodes
3. Install the capacitors
4. Install the transistors
5. Install the integrated circuits.
6. DO NO INS ALL HE LARGE PASS RANSIS OR (Q5) A HIS IME!
Component Order
You’ll notice that the component designations in the directions don’t go exactly in order.
We have grouped them so that all components with the same value appear together. his
makes assembly easier. You’ll find in the parts kit that similar parts, e.g. 3 1K resistors,
are typically (though not always) taped together.
Install the Resistors
In general, you install the resistors by placing the body on silk screen side of the board,
and the leads through the indicated holes. Bend the leads over on the back of the board to
keep the resistors from falling out until your solder them in place. ry to bend the leads in
a direction that won’t lead to solder bridges between traces that should remain
disconnected.
Figure 1-Installing resistors

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We recommend the following procedure:
1. Insert all the resistors of the same value, e.g. R2, R3 and R4.
2. Bend the leads as described above.
3. Solder the leads on the back of the board.
4. Clip the leads.
rack your progress by placing a check-mark in the done column as you install each
resistor. Check resistor values with a meter, or by reading the color code
1
. Orient the
resistor with the fat brown band on the right, then you can read both the Color Code
column and the resistor from left to right.
¼ Watt, 1% resistors
Designation Value Color code Done? ()
R2 1K Brown, Black, Black, Brown, Brown
R3 1K Brown, Black, Black, Brown, Brown
R4 1K Brown, Black, Black, Brown, Brown
R6 10K Brown, Black, Black, Red, Brown
R26 10K Brown, Black, Black, Red, Brown
R27 10K Brown, Black, Black, Red, Brown
R8 20K Red, Black, Black, Red, Brown
R9 20K Red, Black, Black, Red, Brown
R1 15K Brown, Green, Black, Red, Brown
R5 140K Brown, Yellow, Black, Orange, Brown
R7 5K76 Green, Violet, Blue Brown, Brown
R11 3K48 Orange, Yellow, Gray, Brown, Brown
R22 165K Brown, Blue, Green, Orange, Brown
R23 100 Brown, Black, Black, Black, Brown
R24 95K3 White, Green, Orange, Red, Brown
R25 NO LOAD
2 Watt, 5% resistor
Designation Value Marking Done? ()
R12 0.1 0.1
1
See “Appendix 1 - Resistor Color Code” on page 41 to see how to read resistor color codes.

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Install the Diodes
Now install the diodes. Be careful to observe the polarity markings on the diodes. You’ll
notice that one end of the diodes has a band. Match the banded end of the diode with the
banded end of the silk screen.
Warning: Don’t cut the leads of D4-D7 until after the leads have been formed and the
diodes have been soldered into the PCB.
Form the leads of D4-D7 as shown in Figure 2. Solder one lead of each diode while
attempting to keep the body perpendicular to the plane of the board. he anodes of the
diodes can sit on the board.
Figure 2-Form the cathodes of D4-D7 as shown (banded end denotes cathode)
Designation ype, Package Description Done? ()
D1 BZX55B33, DO-35 33 Volt 2% zener diode
D14 BZX55B33, DO-35 33 Volt 2% zener diode
D2 BZX79-B10, DO-35 10 Volt 2% zener diode
D8 1N4148, DO-35 0.2 A, 100 PIV, switching
diode
D9 1N4148, DO-35 0.2 A, 100 PIV, switching
diode
D10 1N4148, DO-35 0.2 A, 100 PIV, switching
diode
D11 1N4148, DO-35 0.2 A, 100 PIV, switching
diode
D12 1N4004, DO-41 1A, 400 PIV, rectifier
diode
D13 1N4004, DO-41 1A, 400 PIV, rectifier
diode
D4 6A4, R-6 6A, 400 PIV, rectifier
diode
D5 6A4, R-6 6A, 400 PIV, rectifier
diode
D6 6A4, R-6 6A, 400 PIV, rectifier
diode
D7 6A4, R-6 6A, 400 PIV, rectifier
diode

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dentifying the glass body diodes
he glass body diodes have the following identifying marks. If your vision is like mine,
you may need good light and a magnifying glass.
• 1N4148, D8-D11, has the number 48 visible
• BZX55B33B, D1 and D14, has the number 33 visible
• BZX79-B10, D2, has the number 10 visible
Also, typically when these diodes are packed, you can preliminarily identify the types
because:
• he 4 1N4148 diodes will typically be taped together
• he 2 BZX55B33B diodes will typically be taped together
• he 1 BZX79-B10 diode will be by itself
D4-D7, opaque
black plastic
package
D3, D12, D13,
DO-41, opaque
black plastic
package
D1, D1, D8-
D11, D14,
DO-35 glass
package

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Install the Small Capacitors
Now install the capacitors:
Designation Value Description Done? ()
C1 10 µF 100V electrolytic (polarized),
cylindrical shape
C2 10 µF 100V electrolytic (polarized),
cylindrical shape
C3 10 µF 100V electrolytic (polarized),
cylindrical shape
C4 100 nF 50V, Z5U, +/- 20%, marked 104
C5 10 nF 400V, film, 20%, box shaped
Notes:
1. C1 is polarized, showing a minus sign (-) on the negative end of the capacitor.
Make sure that the minus sign faces away from the plus sign (+) marked on the
silk screen for C1.
2. C2 is also polarized. he Rev A PCB’s have a silk screen error in the drawing for
C2. he shape is shown as a rectangle; but there is no no polarity designation. Use
the drawing below to properly install C2. he bottom of C2 should be about ¼”
above the PCB to avoid stressing the leads.
3. C3 is also polarized. Rev A PCB’s are missing the polarity sign. See the yellow
plus sign added to Figure 3.
Figure 3-Blac text shows C2 polarity, yellow plus sign shows C3 polarity

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Install the Transistors
You may have to spread the outside leads a bit to make it easier to insert them into the
board. Do not install Q5 now. It will be installed later.
Orient the transistor so its body shape matches the silk-screen outline. Leave the top of
the transistor about ½” off the board! The lead length prevents stress on the body and
keeps the transistor safe from too much heat during the soldering operation.
Designation ype Description Done? ()
Q2 2N3904, O-92 60 V NPN bipolar transistor
Q3 2N3904, O-92 60 V NPN bipolar transistor
Q4 2N3904, O-92 60 V NPN bipolar transistor
Q6 2N5401, O-92 150 V PNP bipolar transistor
Q7 2N5401, O-92 150 V PNP bipolar transistor
Don t use too much solder on the transistor leads. This is one place where the spacing is
close enough that extra solder might cause short circuit between two leads on a given
transistor. Note that Q4 s collector and base are connected by the circuit board.
Install the Integrated Circuits
Install the integrated circuits.
Orient U1 so that pin 1 on the chip matches pin 1 on the silk screen.
Orient U2 to match the silk screen outline.
Designation ype Description Done? ()
U1 LM258 or
LM358
8 Pin DIP
U2 L431, O-92 Programmable shunt regulator
Figure 4-Pinout of U1, viewed from the top

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Install the Big Capacitors
Install C6 and C7.
C6 and C7 are polarized. Be careful to get the polarity correct. Double check their
polarity before you solder them in place. They have large terminals, so it will take a fair
amount of heat and solder.
Designation ype Description Done? ()
C6
2
4700 µF/80V Electrolytic capacitor
C7 2200 µF/160V Electrolytic capacitor
Final Inspection of the Circuit Board
After you’ve taken a break, look over your completed circuit board one more time.
Looking on the component side, double check:
1. polarity (banded end) of diodes matching the banded end on the silk screen.
2. polarity of C1 (minus sign away from the indicated plus sign on the silk screen).
3. polarity of C2 (per the indicated drawing).
4. polarity of C2 (per the indicated drawing, Figure 3).
If you get one of these polarities wrong, there is a good chance that the power supply
won’t work, or there will be damage when you power it up.
Look at the solder side of the board. Make sure that:
1. All component leads are soldered (it’s easy to forget one or two, and that will
cause either unreliable operation, or no operation at all!)
2. here are no solder bridges between pads which should be isolated. Solder
bridges may stop the power supply from working correctly.
Figure 5-Completed Power Supply Circuit Board awaiting Q5 installation
Power Suppl Final Assembl
In this section, you’ll install Q5 while you mount the power supply circuit board to one of
the three finned heat sinks. Note that the three heat sinks are identical.
2
In some kits, this may be a 3900 µF 100 Volt capacitor.

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Figure 6-Note the rounded brac ets used for the power supply heatsin and PCB
(XXX needs new picture)
1. Use two 6-32x3/8” screws to fasten a pair of mounting brackets to the heat sink,
placing the screw through the 9/64” clearance hole in the bracket. Note that one
hole in the mounting bracket is a 9/64” clearance hole, the other hole is threaded
to accept a 6/-32 screw. Don’t tighten the screws yet. Make sure you use the
brackets with the rounded edges to mount the power supply PCB.
2. Use two 6-32x1/4” screws to fasten the PCB to the mounting brackets and heat
sink. Don’t tighten the screws yet. One of the screws is visible in Figure 17, the
other is hidden behind the large output capacitor.
3. Place a thin film of thermal compound on the metal tab surface of Q5 as shown in
Figure 7. Inset Q5 into the circuit board as shown in Figure 8. Secure it in place
with a #6-32x1/2” screw, just finger tight for now. he side with the thermal
compound must attach to the heat sink.
4. Line up the PCB, brackets, and Q5 so everything is square and fits comfortably,
then tighten the 5 screws:
a. 2 that hold the brackets to the PCB
b. 2 that hold the brackets to the heatsink
c. 1 that holds Q5 to the heatsink.
Figure 7-Placing thermal compound on Q5

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Figure 8-Installing Q5 on the heatsin and to the PCB
Figure 9-Remember to solder Q5's leads
5. Solder the three leads of Q5 on the component side of the board, and clip the
leads. Inspect your work from both the top and the bottom of the board to make
sure there are no solder bridges between the leads.
Attach the Power Suppl Ground Wire
1. Cut an 8” length of black 18 AWG stranded wire. Strip 3/8” of insulation from
both ends of the wire.
2. Insert one end of the wire into the GND eyelet (this is different from the PGND
eyelets!) of the power supply PCB. Insert it from the component side and solder it
on the solder side.
3. Insert the other end of the wire into the eyelet of a #6 lug. Crimp the wire and
solder it to the lug.
Figure 10-power supply with attached ground wire
Note: he X1, X2, VCC, and PGND eyelets will remain open until a later assembly step.
Once the power supply/heat sink module is completed, set it aside and proceed to the next
section, where you will build the amplifier modules.

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Section 3: Assembling the Amplifier Circuit Boards
his section details the process of building the circuit boards. We start with an overview
on this page. he specifics you need to start building begin on the next page.
In general, you’ll start with the components that lay closest to the board, working your
way toward the taller components. You will:
1. Install the resistors
2. Install the small capacitors
3. Install the diodes
4. Install the LEDs
5. Install the medium size capacitors
6. Install the transistors
7. Install the big capacitor
8. Wind and install the output inductor.
9. Install the LM3886.
Install the Resistors
In general, you install the resistors by placing the body on the silk screen side of the
board, and the leads through the indicated holes. Bend the leads over on the back of the
board to keep the resistors from falling out until your solder them in place. ry to bend
the leads in a direction that won’t lead to solder bridges between traces that should
remain disconnected.
We recommend the following procedure:
5. Insert all the resistors of the same value, e.g. R14, R19, R20, and R21.
6. Bend the leads as described above.
7. Solder the leads on the back of the board.
8. clip the leads.
Figure 11-First four resistors are installed, leads bent on the bac side, but not yet soldered.
urn the page for specific directions about each resistor.

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Figure 12-leads soldered and clipped
When you have completed this section, there will only be one empty resistor slot, R16, a
no-load, which will remain empty.
Keep track of your progress by placing a check-mark in the done column as every resistor
is installed. he resistor values can be checked with a meter, or by reading the color
code
3
. Orient the resistor with the fat brown band on the right, then you can read both the
Color Code column and the resistor from left to right.
3
See “Appendix 1 - Resistor Color Code” on page 41 to see how to read resistor color codes.

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Designation Value Color Code Done?
R14 10 Brown, Black, Black, Gold, Brown
R19 10 Brown, Black, Black, Gold, Brown
R20 10 Brown, Black, Black, Gold, Brown
R21 10 Brown, Black, Black, Gold, Brown
R13 100 Brown, Black, Black, Black, Brown
R1 51K1 Green, Brown, Brown, Red, Brown
R2 51K1 Green, Brown, Brown, Red, Brown
R3 100K Brown, Black, Black, Orange, Brown
R5 100K Brown, Black, Black, Orange, Brown
R7 100K Brown, Black, Black, Orange, Brown
R8 100K Brown, Black, Black, Orange, Brown
R4 1K Brown, Black, Black, Brown, Brown
R6 1K Brown, Black, Black, Brown, Brown
R9 1K Brown, Black, Black, Brown, Brown
R18 1K Brown, Black, Black, Brown, Brown
R10 1K, 0.1% Brown, Black, Black, Brown, Violet
R11 20K, 0.1% Red, Black, Black, Red, Violet
R12 20K Red, Black, Black, Red, Brown
R17 1K (1 Watt)
5%
Brown, Black, Red, Gold (less stripes on
a 5% resistor)
R15 10 (1 Watt) Brown, Black, Black, Gold, Brown. his
resistor has a larger body than the others.
R16 his Location Remains Empty
Note: R8 and R18 are near each other on the board. Be careful...don’t mix them up!
Install the Small Capacitors and the Diodes
Now we’ll install the following small capacitors:
Designation Value Marking Done?
C3 220 pF 221
C4 220 pF 221
C9 47 pF 470
Here’s what these three caps look like (not to scale):
Next we install diodes D1 and D4.
Be careful! Diodes have a polarity. Make sure the band on the diode aligns with
the banded end of the silk screen!
Designation Value Marking Done?
D1 1N4004 4004
D4 1N4004 4004

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Here’s what the diodes look like (not to scale):
Next we install LEDs D2 and D3 (Light Emitting Diodes – note that in normal operation,
these diodes will be dark. However, in a fully darkened room, you’ll see a dull green
glow from the powered LEDs.)
Be careful! Light Emitting Diodes have a polarity, also! Read carefully to make
sure you re putting the diodes in the right way! The cathode of the LED is
indicated by a bar (negative sign) molded into the package. On some packages,
there is no bar, but seen from the top, the circular outline with have a flat side.
That flat side is the cathode. Finally, if the leads are uncut, the shorter of the two
leads will be the cathode.
Designation Value Marking Done?
D2 1 style none
D3 1 style none
Figure 13-showing LED cathode orientation
Last Capacitors and the Transistors
Now, the medium tall polarized electrolytic capacitors:
C1 and C6 are polarized. Make sure the negative sign on the capacitors faces
away from the positive sign on the silk screen!
Designation Value Marking Done?
C1 100 µF, 50 V 100 µF, 50 V, and minus sign for polarity
C6 47 µF, 100 V 47 µF, 100 V, and minus sign for polarity

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And the non-polarized capacitors:
Designation Value Marking Done?
C2 1 µF, 63 V or
100V
1 uF, 63 V or 100V (box shaped mylar
capacitor)
C5 0.1 µF, 100V 104
C8 0.1 µF, 100V 104
C10 0.1 µF, 100V 104
Install the transistors. Spread the outside leads a bit to make it easier to insert them into
the board.
Orient the transistor so its body shape matches the silk-screen outline. Leave the
top of the transistor about ½” off the board! The lead length prevents stress on the
body and keeps the transistor safe from too much heat during the soldering
operation.
Designation Value Marking Done?
Q1 2N5551, NPN 2N5551
Q2 2N5551, NPN 2N5551
Q3 2N5551, NPN 2N5551
Now install the speaker coupling capacitor:
Watch the polarity! Make sure the minus sign faces away from the plus sign on the
silk screen. That puts the minus side of the cap along the outer edge of the circuit
board.
Designation Value Marking Done?
C11 10000 uF 63V 10000 uF, 63 WVDC
he speaker coupling capacitor will either snap or push into place. Verify once more that
you have polarity correct, and then solder both speaker terminals to the circuit board.
his will probably take more heat, time, and solder than anything you have soldered up to
now.
Winding the Output Inductor
his step takes just a bit of finesse, but if you’ve come this far, you have nothing to worry
about. If you’re a bit frazzled, take a break before proceeding.
here...feel better? OK, let’s go. Just follow these steps, measuring the wire length
carefully if you want to succeed the on first shot. Note that these pictures were taken
with a 3300 µF output capacitor. he ones supplied with the kit are larger, at 10000 µF,
and will be significantly taller.
1. Cut a 21 1/2” length of 18 AWG solid wire supplied with the kit.
2. Strip back 3/8” of insulation from both ends of the wire. Be careful not to nick the
conductors.
3. From the component side, place one stripped end of the wire into the L1A
terminal. Route it around the output capacitor as shown in (see Figure 14) Solder
the wire into the L1A hole.

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4. Wind 5 turns of wire, closely spaced, so it looks like Figure 15. When you get to
the end of the coil, fold the end across the existing turns, toward the L1B hole.
5. Pull the end of the wire through the L1B hole, and solder it on the back of the
board.
Figure 14-Starting to wind the output inductor
Figure 15-finishing step for the output inductor
Final Inspection of the Circuit Board
After you’ve taken a break, look over your completed circuit board(s) one more time.
Looking on the component side, double check:
5. polarity (banded end) of D1 and D4 matching the banded end on the silk screen.
6. polarity (flat end, or molded bar end) of LEDS D2 and D3, placed toward the
outside edge of the board.
7. polarity of C1 (minus sign away from the indicated plus sign on the silk screen).
8. polarity of C6 (minus sign away from the indicated plus sign on the silk screen).
9. polarity of C7 (minus sign close to the edge of the board).