#321 cordwood-too
The Cordwood Puzzle returns! Boldport Club Project #13, May 2017
Notes
The original Cordwood Puzzle became an instant classic with club members, and the concept returns this year with a brand new puzzle. The cordwoods evoke an era of stuffing massive components into small spaces. This is real hardware!
As before, it really is a puzzle, so if you don’t want any spoilers - read no further.
Unboxing and Parts Count
| Ref | Part | Qty |
|---|---|---|
| R2,4,6,8,10,12,14,16 | 10KΩ 2W resistor, Multicomp MCMF02WJJ103A10 | 8 |
| R1,3,5,7,9,11,13,15 | 220Ω 2W resistor, Multicomp MCF 2W 220R | 8 |
| C1 | 1uF ceramic capacitor, AVX SA305E105MAR | 1 |
| Q1-8 | n-channel MOSFET transistor, Fairchild 2N7000 | 8 |
| 10-pin through-hole header, Multicomp MC34739 | 1 | |
| 10mm yellow LED, Kingbright L-813YD | 4 | |
| 10mm green LED, Kingbright L-813GD | 4 | |
| 25mm M3 standoff, ETTINGER 05.03.251 | 1 | |
| M3 screws | 2 | |
| PCBs | 2 | |
| Piece of 0.84mm diameter 20AWG hookup wire | 1 |
Power
The LEDs are rated for 20 mA with forward voltage of 2.V (yellow) and 2.2V (green). Therefore, with the current-limiting resistor of 220Ω, the maximum supply voltage is around 6.5V.
How It Works
Each LED is switched by a corresponding MOSFET. The MOSFET gate is pulled high by default with a 10kΩ resistor, so the defualt LED state is ON.
Each gate is also connected to a pin. If these are pulled to ground, the corresponding LED turns off.
Construction
With it’s twin, the original Cordwood..
Credits and References
- Cordwood Too - Boldport Product Page
- Cordwood Too - on the community site
- 2N7000 datasheet
- 10mm yellow LED, Kingbright L-813YD data
- 10mm green LED, Kingbright L-813GD data
- LEAP#269 cordwood - the original Cordwood project
- ..as mentioned on my blog