Temperature controller

ronsimpson

Joined Oct 7, 2019
2,539
I am using a temperature controller and heating element that I did not choose. It does not work the way I want, and the price is very high.
I am making/looking for a proof-of-concept heater controller. Heater load is about 100 watts.
Option 1) I am looking for a low-cost temperature controller, displays in (C) and works from 30C to 175C. Temperature set by hand. $50.00 Option 2) All other instruments are controlled by ethernet. The only controller I have found that talks ethernet is$3000.00.
Option 3) Use a raspberry Pi-3 and a SS relay and make one from nothing. (I do not have that much time)

Thank you for any ideas you have.
RonS.

Ian0

Joined Aug 7, 2020
6,711
Thermistor - comparator - relay. Can't get much simpler.

ronsimpson

Joined Oct 7, 2019
2,539
A controller like the one in post #2 is $35 in the US or$11 to $17 in China. I ordered the US one (ship next day) and they are having it sent to me via China (come this month?). Controllers that talk ethernet are thousands of dollars, but I found one that talks RS485 for about$100.

MisterBill2

Joined Jan 23, 2018
13,799
The big advantage of an ethernet linked controller is that it is easier to hack by those who want to cause problems.

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ronsimpson

Joined Oct 7, 2019
2,539
The big advantage of an ethernet linked controller is that it is easier to hack by hose
I wish I knew how hard/easy it is. I have test equipment all over the world. My work group is in Germany, Japan, China & US. We use each other's equipment over night. I think the risk is about the same as having a PC on the internet.

MisterBill2

Joined Jan 23, 2018
13,799
OK, I was referring to wireless ethernet hacking. Wired connections require physical access and that can be a serious barrier for many. My error of not being specific enough.

wayneh

Joined Sep 9, 2010
17,189
What level of remote control are you looking for? Smart switches and smart thermostats are quite inexpensive and the better brands have a good-enough level of security. I have several in the house. I can’t imagine needing more.

ronsimpson

Joined Oct 7, 2019
2,539
What level of remote control are you looking for?
This is a test setup with many machines. PC, scope, signal generator, power supplies, heat/cool all on a wired network. For the heater I need to set the temperature ( 30C to 175C ) and run tests again. It is common for the temperature to be set every hour via a PC. When the cooler is connected, we go down to -40.

wayneh

Joined Sep 9, 2010
17,189
So you need to change the temperature set point remotely. Unfortunately a home thermostat likely cannot be programmed to accommodate that range of temperature. Hmmm…. That range rules out a lot of cheap, off-the-shelf solutions and puts you more in the realm of lab equipment, which unfortunately is not cheap.

My Arduino kit has a temperature sensor that can use a platinum RTD probe, which I think might handle that range. Have you looked into microprocessor solutions? They offer a DIY approach to lab equipment. I haven’t tried internet control of such a thing but I gather it’s quite common. Security is an issue with a DIY approach.

I have ordered something very similar to what Danko suggested in #2. ($11.00) It cannot be controlled by remote but that will work for a month. I found a$100 controller that is programmable by RS485 and has optional adapters for USB, RS232.