DPDT to SSR setup

[QldKev]

Either I'm brilliant, or I have not got a clue about electronic stuff. The latter I know is true...





Can it be done?

 

[Whiteferret]

Either I'm brilliant, or I have not got a clue about electronic stuff. The latter I know is true...

npn2.gif


Can it be done?

If you got the polarities out of the Pids right then SSR B would only be able to turn on when SSR A was on.
I can't seem to attach a pic at the moment I've drawn up a diagram from Edaks circuit that I think is right will try to upload/attach again.

View attachment 4011.bmp


Dammit how do you get it to show up as a picture?

 

[QldKev]

If you got the polarities out of the Pids right then SSR B would only be able to turn on when SSR A was on.
I can't seem to attach a pic at the moment I've drawn up a diagram from Edaks circuit that I think is right will try to upload/attach again.

4011.bmp


Dammit how do you get it to show up as a picture?

With the pic did you click "Add to Post" after you "Attached Files"?

With the polarities I would use both +'ve terminals, I just drew it that way to make it easy. Why wouldn't it work with SSR_B? I thought that was where the PNP was useful, when the input to the base of the transistor was low, it would allow the current to flow to SSR_B?


Using the 4011 could we energize it from the pids output. Something like this




Also how would you setup the 4011, just solder the wires to it or solder it onto some sort of a board first and then solder wires to it?


Thanks

QldKev

 

[Whiteferret]

With the pic did you click "Add to Post" after you "Attached Files"?

Mmmm can't remember think i did.

With the polarities I would use both +'ve terminals, I just drew it that way to make it easy. Why wouldn't it work with SSR_B? I thought that was where the PNP was useful, when the input to the base of the transistor was low, it would allow the current to flow to SSR_B?

F*&k its been years since I did any basic electronics i thought that you needed a positve with regards to the collector for it to conduct in the direction of the arrow.

Using the 4011 could we energize it from the pids output. Something like this

4011_2.gif



Also how would you setup the 4011, just solder the wires to it or solder it onto some sort of a board first and then solder wires to it?


Thanks

QldKev

I'm thinking that the symbols you have in the supply lines are diodes to separate the pid outputs and power the 4011 it could work I was thinking of a separate power source.
you can get vero board from jaycar you can just cut it to size and solder wires and jumpers to it you could solder wires to the chip but thats a bit dodgy h34r:



http://www.jaycar.com.au/productView.asp?ID=HP9540

 

[srm]

I have a similar problem - two 2.2 kw elements sharing one 2.4 kw supply. Was there a final recommendation for this thread ?

 

[QldKev]

I didn't end up going this route for mine. I ended up with a mechanical cam switch that I manually switch over the circuits. So as soon as it get stable at mash temp I switch the second heat exchanger back to the HLT as one element can maintain the temperature of the batch easily. No real reason I went this way, I just felt more comfortable manually being in control.

Someone else on AHB has implemented this automated switching circuit, but I cannot recall who it is.

 

[srm]

Thanks QldKev

My control box has two PID temperature controllers independently controlling the elements in my HLT and "Hermit". I have wired their SSR control wires through a switch that allows me to select either one of the two elements to keep within the 10A power supply limit.

I have delayed spending money on the obvious solution of upgrading the power supply.

The controller works but I found this thread when looking for ways to improve it.

I liked the apparent simplicity of the two options proposed (the pnp transistor option and the wired AND chip).

However my electronics knowledge is not good enough for me to bridge the gap between two controllers independently outputting 22 to 28 VDC @ 30 mA to their own SSR and one controlling the other through a "chip" with different operating voltages and currents.

It would be good if someone could give me guidance on this.

Thanks again & Regards

Steve