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Assembly Instructions
TinyTrak3 is a fairly simple construction project that can usually be built in less than an hour. You will need a low wattage
pencil-type soldering iron with a small tip, some thin solder, and a pair of diagonal cutters. The microcontroller (U1) is
static sensitive, so use standard precautions. For each item, insert on the component side (white silk-screened side), then
turn the board over and solder the leads to the pads on the trace side. Be sure to only solder the correct pad, and do not
let any solder touch any other pad or trace. Trim any excess leads with diagonal cutters after soldering each component.
The following checklist will be useful to insure all components are properly assembled.
Before beginning, consider how the TinyTrak3 will be mounted. If mounting with the DB-9 connectors inside the
case, it will be easier to cut the PCB before inserting components. See Case section for more information.
Install the 18-pin IC socket for U1. Be sure to align
the notched end of the socket with the marked end
on the silk screen. It may help to temporarily slide
J1 into position without soldering to make the
socket sit flat on with the PCB. First solder just two
diagonally opposite pins of the socket, and check
that the socket sits flat on the PCB. Then solder the
remaining socket pins. Do not insert the chip into
the socket at this time.
Install capacitors C1 – C5. (0.1uf, 104). Direction
does not matter. If the leads need to be formed to
0.1 inch spacing, be careful not to bend too close to
the yellow ceramic material. Bend the leads apart
slightly after insertion to prevent them from falling
out when the PCB is upside-down for soldering.
Install transistor Q1 (2N2222A), which provides
Push-To-Talk (PTT) for the radio transmitter. Be
sure to orient flat side to match the flat side shown
on the silk-screen pattern. Q1 is just above C5.
Install voltage regulator U2 (78L05). Be sure to
orient flat side to match the flat side shown on the
silk-screen pattern.
Install ceramic resonator Y1 (10 Mhz), which
provides the clock oscillation for the chip. Direction
does not matter.
Install resistors R1 (8.2K gry-red-red), R2 (3.9K,
org-wht-red), R3 (2K, red-blk-red), R4 (1K, brn-blk-
red), & R5 (220K, red-red-yel) which create the 4–
bit digital to analog resistor ladder. For each
resistor, bend one of the leads 180 degrees at the
bulb of the resistor so that both leads are parallel
and 0.1 inch apart. See the image to the right.
Install vertically on the board. Polarity does not
matter. Bend the leads apart once inserted to hold
in place.
Install resistors R7 and R14 (10K, brn-blk-org)
using resistor instructions above.
Install resistor R8. (2.2K, red-red-red). Use
instructions for resistors above. Note: If TinyTrak3 will be used with a radio that does not key via current through
the microphone line, such as mobile radios and Kenwood handhelds, R8 will not be needed. If R8 is used, you
should not wire PTT OUT to the radio.
