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Project Notes

#411 cordwood-three

Custom build of the Boldport Club Cordwood Puzzle III, Project #25, May 2018, with an archway layout and a spring-loaded LED trigger machanism.


Here’s a quick demo of the build on a custom test jig “LED Blinky Machine”..



This is the third Boldport Club project in the Cordwood series. See my build of the first and second. Here they are all together:


The Kit

The kit arrrived in the familar brown paper



If you want to build this kit, the easiest way is to join the club and order the BoldportClub kit. But you could do it without the kit: the PCB design is open source so it is relatively easy to make an identical (or similar) set of boards, and the parts are relatively easy to obtain:

Qty Original Part Mouser Equivalent
x6 220Ω 2W resistor, Multicomp MCF 2W 220R 603-RSF2WSJR-52-220R
x6 10KΩ 2W resistor, Multicomp MCF 2W 10K 588-OY-10K-E
x6 MOSFET n-channel transistor, Fairchild 2N7000_D26Z 512-2N7000
x1 1µF ceramic capacitor, AVX SA305E105MARC 80-C440C105Z5U-TR
x6 10mm green LEDs, Kingbright L-813GD 696-SSLLX100133SGD
x1 25mm M3 female-female standoff, ETTINGER 05.03.251 761-M1272-3005-SS
x1 25mm M3 female-male standoff, ETTINGER 05.13.251 761-M2120-3005-SS
x2 M3 screws, DURATOOL M38 CSSTMCZ100-  
x1 10-pin 2.54mm header, Multicomp MC34739 710-61301011121
x5 6cm of 20AWG wire  


The circuit is similar to the other cordword projects: essentially an array of LEDs with low-side NFET switches. By default, the LEDs are on with a pull-up resistor on the MOSFET gates. The gate is exposed via pin header so it can be pulled low (turning off the LED).



The conventional construction is a vertical stack. The Boldport guide outlines the construction:


I played around for a bit looking for alternatives, and settled upon an archway style which I found quite appealing;-)


So that’s working fine - I can toggle the LEDs by pulling any of the 6 gate pins low.


Here are my working notes for re-arranging the connections…


A Custom Test Jig - LED Trigger Machine

So without getting too fancy, I wanted a nicer way of mounting and testing the project. One thing lead to another, and soon I had a completely pointless LED blinking machine:

  • I used the box from The Boldport Gent project as a base
  • 4 x AAA in the box
  • power switch
  • and a spring-loaded trigger mechanism for blinking the LEDs


Close up on the trigger machnism - a bit of ad-hoc wire craft and a spring:


Power and switch connections inside the box:


Side view..


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.