Comment on Disconnect wire to close a switch with a simple circuit
raspberriesareyummy@lemmy.world 5 days ago
I was never excellent at analogue electronics but your very first diagram looks perfectly fine, with the tripwire connecting the transistor base to ground. Preferably with a large resistor to avoid draining the battery quickly. A grounded base should effectively close the collector-emitter path.
Romkslrqusz@lemmy.zip 5 days ago
That’s where I think I’m having the biggest issue. I’ve been experimenting with different resistors, 20Ω is the only value so far that doesn’t result in the module power cycling the resistor starts to cook, I think it is rated for 1/8W and I could go with a higher wattage rating but I don’t want to drain the 300mAh battery too fast
raspberriesareyummy@lemmy.world 5 days ago
I couldn’t imagine the transistor flipping when it’s base is actually grounded. Did you try an NPN transistor? I am not familiar with FETs, maybe they behave weirdly here?
Romkslrqusz@lemmy.zip 5 days ago
It is an NPN, It isn’t flipping when base is pulled to ground / is behaving as expected.
When using NPN, the problems were related to the resistor. I managed to find a “sweet spot” at 330ohms where the module is able to turn on and play without cycling and the resistor sits at a comfortable enough temperature.
I’m going to try timing plugging in the battery so that the resistor doesn’t shed all of its power before the gift is opened :)
raspberriesareyummy@lemmy.world 5 days ago
Sorry, I clearly misunderstood - so the problem isn’t the tripwire implementation but rather the high current that you need to switch. My first thought was (as someone else suggested) to use a relay, and a quick web search brought me to this mention of “Darlington” transistors: itp.nyu.edu/…/transistors-relays-and-controlling-…