I have a project that has two separate circuits. One is a small voice recorder (like the kind you find in greeting cards) that requires 9VDC and the other is a simple flickering LED that runs on 3VDC. The flickering LED came out of a flickering candle and was driven directly by a 3V button cell, so the LED itself contains a circuit for flickering effect, resistors etc.
I realize I could run both circuits from one 9VDC power source if I put a 300 ohm resistor on the LED but the voice recorder already has it's own leads and battery connector and I already have a 2 AA battery holder, so I think it would just be easier to keep them separate. The problem is, I need to use a single SPST switch for both circuits because I don't have time to find a DPST switch that fits a .25" diameter hole (if they even exist..I couldn't find one) and I don't want two separate switches.
Lets assume I run the two negative leads from each circuit (with two different voltages) through the SPST switch. Would that be OK as long as the positive leads are still isolated? Will each circuit still only get either the 9V or 3V that I hope is being returned through the respective positive leads or will I get some other voltage to both circuits? I guess I could test it with a multimeter but it would save me some time and effort if someone already knows the answer.
Thanks for your help.
I realize I could run both circuits from one 9VDC power source if I put a 300 ohm resistor on the LED but the voice recorder already has it's own leads and battery connector and I already have a 2 AA battery holder, so I think it would just be easier to keep them separate. The problem is, I need to use a single SPST switch for both circuits because I don't have time to find a DPST switch that fits a .25" diameter hole (if they even exist..I couldn't find one) and I don't want two separate switches.
Lets assume I run the two negative leads from each circuit (with two different voltages) through the SPST switch. Would that be OK as long as the positive leads are still isolated? Will each circuit still only get either the 9V or 3V that I hope is being returned through the respective positive leads or will I get some other voltage to both circuits? I guess I could test it with a multimeter but it would save me some time and effort if someone already knows the answer.
Thanks for your help.