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Discussion Starter #1
I have a 1100 mah, 12vdc battery that I want to switch using a miniature, solid state, SPST relay. How tiny? It needs to fit in the small recesses of a handheld trouble lamp, so perhaps about 10mm x 12mm x 15mm-ish: tiny. I'll be using the battery to power a 12vdc light bulb, so, what, maybe 1-5 amps? I'm guessing on the amperage, but that's probably close enough.

Amazon suggested this, at 1.8mm x 1.4mm x 1.9mm, but it's a bit too big:

726572


https://www.amazon.com/General-Purpose-Relay-Power-JQC-3F/dp/B07PMW33V6

Any suggestions you might have that I could look at?

Thanks.
 

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Well several things here. Those are not solid state relays, they're mechanical. Second, I think your dimensions are cm, not mm. Third, what are you controlling the relay with?
 

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Discussion Starter #3
I'm always open to learning, so thanks. I'm an armchair electronics guy, self taught, far from being the expert.

No, mm is correct. I'm really, really hoping to find something that's that tiny. I'm using a mechanical slide switch to switch it on and off.

The reason I'm looking at implementing the relay is that I had had the full current going through the little slide switch, silly me. I noticed it was getting warm enough that the hot glue I was using to hold the slide switch in place was heating up and deforming, allowing the slide switch to retract back inside the device and disappear.

No, it's not engineering: it's just me the hobbyist doing the best I can.
 

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I use a logic level MOSFET in the project right now with an Arduino to get a dimming effect. If I use a second MOSFET to control the battery with that same switch, how do I figure what size resistor to use to connect to the gate?
 

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I use a logic level MOSFET in the project right now with an Arduino to get a dimming effect. If I use a second MOSFET to control the battery with that same switch, how do I figure what size resistor to use to connect to the gate?
Use a 2.2K resistor with 12v to the gate.
 

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Discussion Starter #7
TY. In teaching myself to fish (heh, heh) and your help, was 2.2K chosen because 12/2200 = 5ma and that's... a good guess, and I have to start somewhere? I'm wanting to get my feet on solid ground, and I'm just looking for guidance.

Thanks.
 

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Ha! You're over thinking! No real formula for it, I typically use a 2.2K for the base or gate on transistors.
 
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