DIY Thermostat

[Daniel Chubb]

Hi all,

I set myself a challenge a few weeks back - to create a thermostat suitable for use in brewing.

After going to my local home brew shop and finding out they were $70 for a basic model, I thought it might be worth sharing with you fine people. I managed to put together a prototype for under $20.

The thermostat can be set to any level that the thermistor works at - So I reckon it would be useful for both fermentation and mash temperature control.

I have used an arduino, thermistor, and 4-digit 7-segment display for this project. The seven segment display gives both the current temperature and set temperature, and the set temperature can be reprogrammed on the fly.

The image attached is what the prototype looks like on my desk. Obviously you can package it any way you like.

If anyone want to build the same thing, I am happy to share the details.

 

[BrockHops]

Good work Daniel, are the bits easily sourced?

 

[Daniel Chubb]

Good work Daniel, are the bits easily sourced?

Relatively so. I am reworking it to be even cheaper with a 5v arduino pro-mini and getting the thermistors on their own. The hard part is sorting out the libraries to make the seven segment display run, which I think I have nailed now.

The parts list as it stands:
10K thermistor
3x 10K resistors
4-digit decimal seven segment display (with TM1637 driver)
2x contact switches
Arduino uno (soon to be 5v pro-mini)
10A relay for heating/cooling circuit

If I get it going on a pro-mini, it will need a 5v power supply as well.

edit: I should add that these parts are readily available locally, but *much* cheaper by mail order from overseas.

 

[Daniel Chubb]

Just an update:

The project is now working on the smaller circuit, and my first veroboard prototype is done. It will run up to 10A @ 250v AC in either a heating or cooling circuit, and the circuit is now working on 250v AC (needed a DC power supply previously).