Cordwood Puzzle Three
A Third in a series of
In the 1950s and 1960s inventive engineers saved space by using the 'cordwood' assembly, where components were sandwiched in between two circuits boards. This construction became less useful with reduced component sizes, PCB manufacturing advances, more compact integration, and surface mount technology, but is still a lovely piece of history. Combining both old and new, the Cordwood Puzzle series of projects are a tribute to this construction and to the engineers who came up with it.
The puzzle is to correctly assemble the circuit with the components at hand. Once completed, all LEDs light up when power is applied. When connected to a controller board each LED can be individually controlled.
Unfortunately(!), all the comprehensive assembly guides were mysteriously missing from the kits.
The kit contains
x6 220Ω 2W resistor, Multicomp MCF 2W 220R
x6 10KΩ 2W resistor, Multicomp MCF 2W 10K
x6 MOSFET n-channel transistor, Fairchild 2N7000_D26Z
x1 1µF ceramic capacitor, AVX SA305E105MARC
x6 10mm green LEDs, Kingbright L-813GD
x1 25mm M3 female-female standoff, ETTINGER 05.03.251
x1 25mm M3 female-male standoff, ETTINGER 05.13.251
x2 M3 screws, DURATOOL M38 CSSTMCZ100-
x1 10-pin 2.54mm header, Multicomp MC34739
x5 6cm of 20AWG wire
x3 Lovely PCBs
Cordwood Puzzle Three is an open source design, as is most of our work. You can find the design files for the hardware and packaging at our GitHub repository. You can edit the design files using our own PCB design open source software, PCBmodE.
The PCBs were lovingly made by Eurocircuits.
Community contributions for this project are on our community site.
Challenge yourself by assembling the kit without further instruction. Before you do that, however, note the following:
when connecting to a board, make sure that the I/Os can tolerate the voltage levels that are applied to the Cordwood;
make sure that you do not short power and ground; and
don't exceed 20mA per LED.
Even though the original comprehensive are forever lost, we've created an alternative guide of varying difficulty levels. Use any information from the infographic, or don't. Up to you! Finally, the assembly instructions for the first Cordwood Puzzle could be helpful ;)
Or, you could follow Saar building it on camera!