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-   -   Johnson A419 modification (http://www.homebrewtalk.com/f11/johnson-a419-modification-373410/)

mrstevenund 12-11-2012 03:34 AM

Johnson A419 modification
I did a quick search and didn't come up with anything. Does anyone use their temp controller for both heating and cooling? Has anyone modified the controller by adding a switch to short/open the jumper?

I have an insulated box that can fit my 1 carboy or keg. I've been using the temp controller as with one of the carboy wraps, but recently installed a couple thermal-electric cooling units from a wine fridge in it too. My basement is about 64F, slightly cool for Ales, but not cool enough for lagers or for serving the keg. Instead of opening the controller up every time I want to switch from heating to cooling, I'm planning on adding a switch to the top of the controller.

501irishred 12-11-2012 01:01 PM

Are you talking about turning a single stage controller into a dual stage controller? :confused:

DSmith 12-11-2012 01:09 PM

3 Attachment(s)
Yes, I did exactly what you described (pic below).

Attachment 88018

I ended up building a TSS2 unit to simplify needing to consider my basement's ambient temperature and fermentation heat to decide in using cooling vs heating mode. A dual stage controller is GREAT. I still put switches to disconnect power from the relay outlets to deal with cold pitching and lagering and not need to go into the device to change parameters. It will keep very tight temperature to the setpoint control with both relays on.

Attachment 88020

The A419 is now on heating mode to create a conditioning zone in my cold MN basement. It's primary use is bottle conditioning, but is also useful for storing an ale at a stable temperature and get it out of my fermentation chamber. I recently used it to do a yeast starter on a stirplate in the heated box at 68F instead of in the kitchen.

Attachment 88021

See Posts #80, #83 & #84 of this thread for some data-logging experience with the A419 & TSS2 for applications where the probe is on the side of a carboy/bucket and insulated over.


501irishred 12-11-2012 01:38 PM

Excellent work! Sorry, I didn't read your OP well enough.....:mug:

Homercidal 12-11-2012 02:17 PM

I have thought about this very thing just about every time I see my Johnson controller.

The device was not designed with homebrewing in mind. It is an industrial controller designed to do a specific thing, either always cool, or always heat.

However, it would be a VERY simple thing to install a micro switch on the side of the unit to switch between modes. And you may as well add a second switch for cut-in/cut-out while you are at it.

I haven't done it yet since I ended up buying an STC-1000, but I may still.

mrstevenund 12-12-2012 03:40 AM

DSmith - That's exactly what I was planning, just different execution. I have the blue A419 with the pre-wired cords, and a few small switches in my junk box so I was just going to add one of these to the top or side of the A419. I was surprised I hadn't seen a thread like this yet.

I wish I would have known about the TSS2 when I bought the A419. Instead of buying the TSS2 now (which looks like a very nice controller) I was planning on building a dual stage controller with an Arduino board (try to get my embedded code skills back up to snuff, along with the beer tap monitor I posted about a couple months ago).

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