Looking for a way to have a general purpose red led to run on 120vac, and another to drive 24vac for a blue led

 

Hello,

There are no leds that run on 120 Volts AC.
There are led lightbulbs available that run on 120 Volts AC, those have a circuit inside to accomodate the led.
Standard leds can not stand more than 5 Volts reversed voltage.

Bertus

 

For 120vac, I believe a series 390nf cap rated 200 volts or more and a 1N4007 diode wired in reverse polarity across the LED should suffice.

 

Looking for a way to have a general purpose red led to run on 120vac, and another to drive 24vac for a blue led

Step the AC down using a small (as in low power rating) transformer, this will 1) isolate your circuit from the AC supply and 2) greatly reduce the voltage(s) you are dealing with.

Don't screw around with circuits that connect to the unisolated AC supply, there's no need and it can be fatal.

 

a series 390nf cap rated 200 volts or more and a 1N4007 diode wired in reverse polarity across the LED should suffice.

The diode could be a 1N4148 since the reverse voltage is just the LED forward drop.

Alternately you could use four 1N4148s in a bridge circuit, or other small bridge module, to allow the LED to conduct on both half-cycles, reducing the chance of noticeable flicker.

 

https://www.amazon.com/FILN-Indicat...2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1

https://www.amazon.com/6MM-LED-Indi...prefix=24v+led+indicator+light,aps,337&sr=8-8

 

The diode could be a 1N4148 since the reverse voltage is just the LED

Agree.
Whenever I mention using a 1N4148 the TS will ask if a 1N4007 will work as it seems they always have a bunch of already.

 

https://www.amazon.com/FILN-Indicat...2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1

https://www.amazon.com/6MM-LED-Indi...prefix=24v+led+indicator+light,aps,337&sr=8-8

I had problems with my furnace. It runs on 120Vac and 24Vac. I added many lights just like those. From the front panel I can see if the 120 and 24 are OK. If the gas is on, of the fan is on, if the pump is on. I can see if the igniter is on. I no longer need to get the meter out and measure all the test points.