Epaper access control doorlock

this isn’t my project, but i just stumbled across it, and of course they used a spark core!!

cool stuff.


Very cool!

Very possible with lots of money too :slight_smile: That e-paper tablet is $325 all by itself.

Also a word of caution: They paralleled 3 digital outputs together to get enough current to drive their 5V relay coil. This is not recommended as all outputs switch on one at a time and will not load share until they are all on. Load sharing is not guarenteed even either. Better would be to use a simple NPN transistor with appropriate base resistor to amplify the current output of the spark core. Also a clamping/free wheeling/flyback diode should be placed across the relay coils.

2N4401 NPN transistor would be ok with a 220 to 270 ohm resistor on the base would be suitable for most relays coils up to ~100mA. 1N4001 diode would be more than enough for clamping inductive spikes.

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