Build Stage Introduction

General

This kit will actually be built in a single stage, followed by a stage for setting up the interconnections to the rig(s) of choice.

Build Stage Schematic

(Resistor testpoints (hairpin, top, or left-hand lead), as physically installed on the board, are marked in the schematic with red dots)

(Click for Full Schematic)
Build Stageschematic

Build Stage Bill of Materials

Stage Bill of Materials

(resistor images and color codes courtesy of WIlfried, DL5SWB's R-Color Code program)

CheckDesignationComponentMarkingCategoryOrientationNotesCircuit
❏D1BZX55C3V6 zenerBZX55CAxialflat-horizBuild Stage
❏D2BZX55C3V6 zenerBZX55CAxialflat-horiz Build Stage
❏R041 M 1/6W 5%brn-blk-grn-gld brn-blk-grn-gld1/6Wflat-horiz Build Stage
❏C020.1 uF(smt) black stripe (smt) black stripeSMT 1206  Build Stage
❏C014.7 uF 10%475 475Ceramic  Build Stage
❏R0168 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz Build Stage
❏SO18 pin dip socketsocket  Build Stage
❏C030.1 uF(smt) black stripe (smt) black stripeSMT 1206  Build Stage
❏R032.2 k 1/6W 5%r-r-r-gld r-r-r-gld1/6Wflat-horiz Build Stage
❏Q12N3906 PNP transistor2N3906 2N3906TO-92  Build Stage
❏C040.1 uF(smt) black stripe (smt) black stripeSMT 1206  Build Stage
❏R0268 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz Build Stage
❏R054.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz Build Stage
❏R064.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz Build Stage
❏R0768 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz Build Stage
❏R0868 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz Build Stage
❏R094.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz Build Stage
❏R1068 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz Build Stage
❏R112.2 k 1/6W 5%r-r-r-gld r-r-r-gld1/6Wflat-horiz Build Stage

Build Stage Summary Build Notes

Build Stage Detailed Build Notes

Bottom of the Board

Build Stage Bottom View

Mount SMT Caps

Mount SMT caps C02-C04 to the bottom side. Take care not to "launch" one off into space - you'll never find it. Tony has packed one extra in the kit, just for that contingency.

The image above shows the bottom-side location of the mounting pads for each of the 3 capacitors (highlighted in yellow)

CheckDesignationComponentMarkingCategoryOrientationNotes
❏C020.1 uF(smt) black stripe (smt) black stripeSMT 1206 
❏C030.1 uF(smt) black stripe (smt) black stripeSMT 1206 
❏C040.1 uF(smt) black stripe (smt) black stripeSMT 1206 

Top of the Board

Build Stage Top View

Mount the Diodes

The two zeners are to protect the PC USB port, not the AVR chip, as that runs off a 5V supply. They are there with R1 and R3 to limit the USB signals to the PC to nominal level of 3.6v maximum.

Look very carefully at the photo of the top of the board. Depicted as faint yellow dashed lines are two traces from the bottom of the board which, together with the traces at the top, cover all the circuit traces. These are provided visually here should you have a need to trace signals on the board.

Space is quite constrained in the area of the diodes and resistors R1-R4. Components will have to be mounted in a sort of vertically "stacked" fashion in order to fit all of them in. See the photo below:

Close quarters! Mounting the Diodes

Mount D1 and D2, flush to the board. Banded end toward the left-hand edge of the board

CheckDesignationComponentMarkingCategoryOrientationNotes
❏D1BZX55C3V6 zenerBZX55CAxialflat-horiz
❏D2BZX55C3V6 zenerBZX55CAxialflat-horiz

Mount R1 and R3

Mount R1 and R3 flush to the board

Mount R1 and R3 photo
CheckDesignationComponentMarkingCategoryOrientationNotes
❏R0168 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz
❏R032.2 k 1/6W 5%r-r-r-gld r-r-r-gld1/6Wflat-horiz

Mount R2 and R4

Mount R2 and R4, raised slightly above the board, to provide separation between resistor bodies.

Mount R2 and R4 photo
CheckDesignationComponentMarkingCategoryOrientationNotes
❏R041 M 1/6W 5%brn-blk-grn-gld brn-blk-grn-gld1/6Wflat-horiz
❏R0268 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz

Mount remaining resistors

Mount remaining resistors flush to the board

Mount remaining resistors photo
CheckDesignationComponentMarkingCategoryOrientationNotes
❏R054.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz
❏R064.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz
❏R0768 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz
❏R0868 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz
❏R094.7 k 1/4 W 5%y-v-r-gld y-v-r-gld1/4Wflat-horiz
❏R1068 1/6W 5%bl-gry-blk-gld bl-gry-blk-gld1/6Wflat-horiz
❏R112.2 k 1/6W 5%r-r-r-gld r-r-r-gld1/6Wflat-horiz

Mount C01, SO1, and Q1

Mount the ceramic cap, the socket for U1, and the 2n3906 transistor

Mount C01, SO1, and Q1 photo
CheckDesignationComponentMarkingCategoryOrientationNotes
❏C014.7 uF 10%475 475Ceramic 
❏SO18 pin dip socketsocket 
❏Q12N3906 PNP transistor2N3906 2N3906TO-92 

End of stage

Build Stage Completed Stage

Top of the Board

View of Completed Top

Bottom of the Board

View of Completed Bottom

Build Stage Testing

Resistance Tests

Test Setup

Perform this test with the ATTINY (U1) UNPLUGGED from SO1

  • Measure resistances between the test points indicated in the table below
  • Note: the resistance measurements should be within plus or minus 5% of the nominal value

In the next stage, we will connect the USB cable and apply power, via the USB port, to the board, with, and without U1 installed, measuring the voltages.

Resistance Tests

Test Measurements

TestpointUnitsNominal ValueAuthor'sYours
U1-3 to PTTk ohm2.22.18_______
U1-2 to CLohm6867_______
U1-6 to DAohm6867_______
USB-1 to K1k ohm4.74.6_______
USB-1 to K2k ohm4.74.6_______
USB-1 to U1-8ohm00_______
USB-2 to U1-7ohm6866.8_______
USB-2 to USB-1k ohm2.2682.27_______
USB-3 to U1-5ohm6866.8_______
USB-3 to USB-1k ohm950 - 1,050968_______
USB-4 to U1-6M ohmoff the scaleoff the scale_______