Electronics → Re: Low Voltage Illuminated Switch

excellent. thanks again. i really appreciate it.

As tschmidt said, Don't forget the series current limiting resistors for the LEDs...

For 12v, I'd start around 680 ohms, 1/4w (flameproof if possible), 510 or 470 ohms if the LED needs >20ma.

Thanks for that reminder. I will ensure I put them on there.

I've got loads of DEDs if anyone is interesting in taking them off my hands, just pay postage and handling.

No thanks, I've been producing them since the 70's. Ya think I'd learn.

I had some time last night and I was able to build a working POC with the help that you gave me. I even added a diode across the relay. I was able to hear a noticeable delay when opening the switch and hearing the relay disconnect. Very interesting.

Thank you very much for the assistance.

Attached are some pictures, two LEDs, two SWITCHES (not all visible) and one relay.

I only had 1N5408 diodes in my drawer, they are monsters. But work.

I"m going to try to finalize this on a PCB board this weekend and get it into a small project box. Alternatively, I was thinking of just soldiering and heat sinking the components directly inline with the wire. Would that be unwise?

Although I've tinkered with resisters and LEDs and other components in the past, I never really understood what a diode did. So I certainly learned something here. I appreciate the time you spent to explain.

What kind of delay you seeing, .25-.5 sec?

Maybe on the shorter end of your range.

Speed for my application is not an issue.

yeah, typical. I picked the longer one because you said you noticed it.:) It's just the diode. The inductor (relay) is discharging through the diode.

Ahh, excellent point. I have a warped sense of time. Everything i do only takes 15 minutes which drives my wife crazy.

Glad everything is working.

Now that you have one project under your belt time to start thinking about the next one.

/tom