I am using 8 relay module that requires neg 5VDC to trigger each relay. I'm using a toggle on each circuit to a relay. I've got this basic functionality working. But I want to use a 3mm LED as a panel indicator in the same circuit. Not having much luck. If I put the LED and resistor in series with the toggle then the relay only gets about 2v and won't trigger. How do I run 5V to the relay and 2V to the LED from a single toggle?
Here's a diagram without the LED in the circuit.
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Hi Tim,
Seems that your chosen resistor value may be to high which will limit the current available for the series loop (just the right value of R should be calculable when the load current(s) (panel LED and relay) are known.
Also keep in mind that in a series circuit arrangement if the relay's coil requires 5 volts to operate correctly and the diode requires 2 volts, the source voltage will have to be at least 7 volts (sum of the voltage dropped across each load) to overcome the load's internal resistance so the needed amount of current can flow. Hope this helps and if you have any further need just let me know.
Good luck!
Bob Bradley.
Try this.
And for all of the SPSTs I can do this?
Try one and see if there's any issue. The only wild card I see is what is actually on that board to trigger the circuit. It's looking for ground, so I'm presuming it's pulled up to 5V internally. Obviously, without actually knowing for sure what you have, this is only an educated guess.
I will try it tonight. Thanks.
Great, glad that worked out. 
Next iteration...
Is this not functionally the same? Pros, Cons?
Resistors are about 2 cents each, don't be a cheapskate. 
It might work, but you'd have varying brightness on the LED's as more were lit.
Ha. Don't worry, I have plenty of resistors. It was more of a learning question for me.
The ones that used neon lights were high voltage models, those require about 50-60 volts to light!
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