240 SCR with two switches

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Mar 12, 2022
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I looked around and I really couldn't find anything that talks about it. I'm running of of a 20amp twin pole circuit. I'm building a scr. I want one switch for the scr and the other for the outlet for anything besides the element plugged in, like a water pump for cooling. I have most of it built. This is a diagram. Im using blue for red cause I just can't find it. I'm having 3 wires going into the 2 to 6 splitter. Each of those go to a switch. One goes right to the outlet. The other two hot go to the scr and the ground goes to the element. Coming off I want to have a fan wired and a volt amp meter. I wanted to know if the diagram looked on the up and up, and the volt amp meter has that doughnut to measure, do I still just put it on one wire or both cause they alternate? Thanks.


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That's not a useful diagram. You can't actually tell what is connected to what. Also, a bare "SCR" (silicon controlled rectifier) is not really suitable for controlling a heating element, as you need a bi-directional semiconductor switch, i.e. a TRIAC. You also need a proper triggering circuit for the TRIAC. An SSR (solid state relay) controlled by a PID or similar controller (I prefer Auber Instruments EZ Boil controllers, which have better functionality than PIDs) or an SSVR (solid state voltage regulator) controlled by a potentiometer (variable resistor) can be used to control power to an element. An SSR with PID/EZBoil can control power automatically, but an SSVR is strictly manual control (ok for boil control, but not mash temperature control.)

What do you mean by "2 to 6 splitter"?

What is the function of your fan? If you have a properly configured heatsink on your SSR or SSVR, you don't really need a fan.

The coil for the ammeter function of the meter should only have one wire running thru it. If you run both wires, the ammeter measures the difference in current running in the two wires (assuming they are opposite phases.)

Are you running off of a 240 volt circuit, or two 120V circuits. You cannot run from two 120V circuits and have GFCI protection, which is an absolute must for your own safety.

I hate to be a "Debbie downer", but from your post, it doesn't sound like you have sufficient knowledge of electrical circuits to design a safe brewing controller. You should use a design that has been put together by someone with the needed background. You should also consider getting someone knowledgeable to help you wire and test any controller you build. Electricity can kill you, and it is not something to mess with unless you know exactly what you are doing.

I have published multiple controller designs on HBT for anywhere from 1 to 3 elements, and 1 or 2 pumps. I can help you find a design that meets your needs.

Brew on :mug:
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