Can I do this?

I'm planning to use my one PID for the HLT and the eHerms...I assume I switch the SSR controlling 12v to whichever container I want to heat/monitor, also switching the thermocouple of course. My question is, can I also add a pilot light to that control circuit so I can tell when the SSR is actually switched on. Is there enough power in that 12v circuit for that?

if you just want a light that illuminates when the SSR is receiving an active control signal, you can use a panel mounted LED to do this. They take almost no juice to get them to light up.

LEDs need a resistor to limit the amount of current than flows through them, else they burn up. But, if you walk into radio shack, you can get an LED in a panel mount package that already has the current limiting resistor packaged up with it. Just drop it in and wire it up.

FYI: If I understand what it is that you are doing, you really don't need to use two SSRs. You can have your PID feed the SSR and then, after the SSR, you select whether the high current path goes to one device or the other. You really want some sort of manual kill switch in the system to absolutely shut the power off to the elements, so you could just combine the killing/selecting together. SSR feeds out to one place or the other or neither.

Thanks for the help, Walker. The issue with switching the high current to the elements is that one is 110v, the other two are 220. I would really like to switch the low voltage to the ssrs because I'd like to have all that high current stuff in a main box, but the PID, switches and pilot lights would be in a much smaller remote box. Why? Mostly because the 12x12x6 big plastic box is kinda ugly and there's no place where it looks good to me. Vanity I guess.

kklowell said:

...also switching the thermocouple of course.

Click to expand...

Is it a thermocouple or an RTD? Apparently you need to be careful about what type of wire you extend/switch a thermocouple with, as its sensing is based on a potential difference created between the dissimilar metals. Not based on any experience, just something I've come across in my research...

Sensors : auberins.com, Temperature control solutions for home and industry

kklowell said:

Thanks for the help, Walker. The issue with switching the high current to the elements is that one is 110v, the other two are 220. I would really like to switch the low voltage to the ssrs because I'd like to have all that high current stuff in a main box, but the PID, switches and pilot lights would be in a much smaller remote box. Why? Mostly because the 12x12x6 big plastic box is kinda ugly and there's no place where it looks good to me. Vanity I guess.

Click to expand...

Well.... you could still do it with a low current remote box. You just need a couplr more wires between the remote and main boxes. And the 120v vs 240v is not an issue.

But, whatever. Original question was really about the lights and that's not a problem with an LED.

True, and thanks....I'll look for the LEDs. Thanks again.