Posts: 4
Joined: Sun Jun 29, 2014 9:05 pm

DS18b20 and Relay

Tue Jun 11, 2019 3:37 am

I have a DS18B20 hooked up and reporting temperature perfectly. The problem arises when I try to connect a 40A SSR into the circuit. I have the relay Hooked up to 5V power and GND, then I put a transistor between the 5V and GND with a GPIO pin hooked up to the middle pin of the transistor. No matter how I configure it whenever I do this the DS18B20 sensor disappears and stops working for several hours. Meaning I disconnect the relay and have to power down the Pi for a couple hours before the DS18B20 starts working again. After that time, the sensor starts working and reporting again just fine. I really don't understand why it would do this, the relay is rated for 3V-32V to trip it and it borks the sensor as soon as it's plugged in. I'm really open to any ideas on this, I've tried it with multiple Pis and different configurations.

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Posts: 14768
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: DS18b20 and Relay

Tue Jun 11, 2019 3:53 am

Could you show a diagram of how the sensor and SSR are wired up to the Pi please?

Also a link to the description or datasheet of the SSR would be helpful in diagnosing the issue.

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