Digital temp display

I have been having problems with my temp displays. They are k-type and I used my own TC’s. The display seems to work intermittently. One display reads 300 some degrees and the other seems to read ambient. then sometimes they will both shut off and flash -HH-. I am using 1 power supply for both and I am starting to wonder if that’s my problem. Going to isolate them later on and see if I can narrow it down. These Chinese models don’t really have any calibration instructions.

I think i would check for AC votage bleeding through your dc inverter or power supply,just before the gauges.I had that happen on my car alternator,and it made the computor malfuction,and the car ran like lean stalling,chrisler labaren.

I’m with you Joe. I have been fighting the TC/gauges for over a year. If you go to the Carl’s Build thread you will see my latest problems. I have a separate 12 volt battery so I eliminate that problem of grounding to the car. That was the best thing that I have done. The rest is “bad” gauges, I think. I hate to order new ones and still have the same problem. I hope some one who understands electricity better than I do will come in with how to check and correct the problems.TomC

Sorry about the problems guys. I only have one of the “new” style gauges, and every once in a while it will read HH or 00 something. I don’t think they are offering the old style that I have 5 of. I’ve never had a problem with them. I’m not sure what the next, lesser expensive, small model is, maybe the one like Marvin W. has.

I’ve just spent an hour searching the internet and cannot find any digital readout in deg F other than these that we’re having trouble with.

well i think i have them working now (for the time being) I built up my char bed today and it seems like they both are working good. I changed my ice cube to a 12v instead of a 9v. I think that made all the difference. So far they are working on 1 power supply off the inverter. I think I also had a bad TC.

Not cheaper but I haven’t had any problem with them and I really like the alarm. Same thing can be found a little cheaper on Ebay.

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Here are what we use, these are 12 v supply and can read in C or F up to 9999* you can make them output and do some cool stuff with them too.


I’ve got the same thing on my Hopper, it works really well. I like the alarm functionality on it.

Thanks Marvin, and Matt, that gives us 2 alternatives. I’m using 3 of the dual display controller to control and alarm the sawdust burner at the sawmill. 5 years of no problems. Just so folks understand, the dual display in not for 2 thermocouples, but it shows the “set point” in controller mode, and/or the alarm set point on the lower display, and the TC temp on the upper readout. I prefer Marvin’s for us because there is only one number for my brain to digest, and they are a little smaller. I wish I had one on the hopper for alarm purposes.

I have had issues with these units (like Matt’s) on a 304 stainless waster oil boiler that I built. I wonder if the braided cable acts as an antenna. Maybe a RF magnet clamp (like on many printer cables) might help. I have a scope and may have to hunt for these spurious signals.

The rule of thumb on grounding runs of shielded wire is “only ground one end” Grounding both ends can create a ground loop and introduce noise.

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