5500W Element Control: To PID, or not to PID?

[jasonsbeer]

Finally got around to building the PWM according to Walker's diagram. Got it all soldered together, hooked up the power, and NOTHING!

I checked and rechecked my wiring, all the things that were connected were supposed to be connected, but still nothing. I thought about it all day at work.

Luckily, I had another 555 laying in my box of stuff from a previous project. I swapped out the 555 Mouser sent with the one I already had. I now have a happy little test LED flashing at me.

The 555 Mouser sent was kaput.

 

[lustrum]

Those little ICs can get zapped with static electricity or anything, really. I think it was Walker who said he uses a DIP socket to plug the chip into. I do the same thing, because it prevents over-heating the chip when soldering.

Anyway, kudos on the PWM and good luck putting it to use!

 

[SpottedDogBrewing]

See if this link works for you. I created a "shared" project on mouser with all of the parts that I ordered.
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=42dabdadd1

My little schematic:

Note: I couldn't find a little board to solder it to on mouser.com, so I actually went with an item from Radio Shack for that. It was a tiny circuit board meant to take an 8-pin DIP chip (the 555 timer in this case) with holes to insert and solder the other items in. The little board was about $1, but I can't find it on Radio Shack's website anymore.

edit: this is similar to what I bought from Radio Shack to solder it all to:
http://www.mcmelectronics.com/product/21-4610&CAWELAID=220241336

Walker, should the LED on the SSR turn on and off with the setting of the Potentiometer? I finally built one and the SSR led is on continuously and doesn't turn on and off!

 

[Walker]

Walker, should the LED on the SSR turn on and off with the setting of the Potentiometer? I finally built one and the SSR led is on continuously and doesn't turn on and off!

Yes. The LED built into the SSR is an indicator of when the SSR is "on". It should be turning on and off based on the setting of the potentiometer. If your LED is constantly on, then something is wrong with the circuit.

 

[SpottedDogBrewing]

Yes. The LED built into the SSR is an indicator of when the SSR is "on". It should be turning on and off based on the setting of the potentiometer. If your LED is constantly on, then something is wrong with the circuit.

Damn I will have to double check the schematic again Any ideas on what might be wrong?

 

[Walker]

Damn I will have to double check the schematic again Any ideas on what might be wrong?

Off the top of my head... Possibly a mis-wired potentiometer.

An "ALWAYS ON" LED means that the 555 timer is ALWAYS trying to drain the green capacitor but is failing to do so, or the capacitor is instantly re-charging after being drained (similar to the "100%" setting when it's working properly).

If you bought the same part from Mouser.com that I did, it had a total of 5 terminals on it. Two terminals form an ON/OFF switch that you could use for power into the device if you want. The other three terminals form the three tap points of the poteniometer.

There are a couple of ways that you could mis-wire the potentiometer such that it could result in an always on SSR LED.

 

[SpottedDogBrewing]

Off the top of my head... Possibly a mis-wired potentiometer.

An "ALWAYS ON" LED means that the 555 timer is ALWAYS trying to drain the green capacitor but is failing to do so, or the capacitor is instantly re-charging after being drained (similar to the "100%" setting when it's working properly).

If you bought the same part from Mouser.com that I did, it had a total of 5 terminals on it. Two terminals form an ON/OFF switch that you could use for power into the device if you want. The other three terminals form the three tap points of the poteniometer.

There are a couple of ways that you could mis-wire the potentiometer such that it could result in an always on SSR LED.

I did buy the same potentiometer from mouser.com. it has a prong on each side and 3 prongs together out of the center. Which prongs should be used?
Thanks I really appreciate the help:rockin:

 

[Walker]

the three that are grouped together.

 

[SpottedDogBrewing]

the three that are grouped together.

Thanks Walker!! That has to be whats screwed up then. I was using the two outside ones not the 3 grouped together. I'll switch that over tonight to see if something else isn't screwie.
Thanks for the quick response to my ameture questions:rockin:

 

[Walker]

Thanks Walker!! That has to be whats screwed up then. I was using the two outside ones not the 3 grouped together. I'll switch that over tonight to see if something else isn't screwie.
Thanks for the quick response to my ameture questions:rockin:

Ok... but... the circuit requires three connections to the potentiomenter. Were you using the two outside ones and then one of the center three, or do you only have it connected at two places?

 

[SpottedDogBrewing]

Ok... but... the circuit requires three connections to the potentiomenter. Were you using the two outside ones and then one of the center three, or do you only have it connected at two places?

I had the two outside one's and the center one of the three connected. Had the center one of the three as a ground!!!

 

[Walker]

I had the two outside one's and the center one of the three connected. Had the center one of the three as a ground!!!

Woah... Sounds like you better double check everything then.

Ground should only be attached to the two capacitors and the "gnd" pin on the chip!

 

[SpottedDogBrewing]

Woah... Sounds like you better double check everything then.

Ground should only be attached to the two capacitors and the "gnd" pin on the chip!

Look's like the ground is correct the only thing different was the two outside prongs i need to move to the two outside of the 3 grouped prongs. Thanks for the info!!