General discussion • Re: which Raspberry Pi

Hi,

I'm newbie to Raspberry Pi's and my project is this:

temperature sensor. (3vt or 5 vt)
Relay (5vt)

maybe other items that I am unaware of yet, but probably not.

My project is to turn on/off a freezer (120 volts), so that it lowers its inside temperature no more than1 F degree every 3 hours, until it reaches 34 F degrees.

Please tell me which components I need to purchase. Specifically which Raspberry Pi. This Pi will be dedicated to this project and no other.

Thanks very much
Tim

A lot of questions. My take:

My project is to turn on/off a freezer (120 volts), so that it lowers its inside temperature no more than1 F degree every 3 hours, until it reaches 34 F degrees.

It sounds like you are trying to replace the existing thermostat for the freezer. If that's the case, you will have to set that to it's lowest setting so only yours is in control.

You will need to have a relay rated to the starting amperage for the freezers compressor. For safety sake, choose relay with independant power and an opto-isolation from the RPI.

As someone mentioned, a DS18B20 is a good as it will not be affected by condensation.

Please tell me which components I need to purchase.

You are better to seek out RPI projects for temperature sensing, time elapsed calcuations and external relay. We will provide pointers but your project covers several areas.

Specifically which Raspberry Pi.

As someone else mentioned, a Raspberry PI PICO will do the job BUT is a microcontroller running firmware as opposed to the other RPI's that run an OS. It comes down to your comfort level. If you'd like.a full OS then a Raspberry PI ZERO would be good.

Good luck

Statistics: Posted by DS256 — Wed Mar 12, 2025 7:56 pm

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