Arduino + SSR

Other Hardware General Electronics
1

Hi

As I know now what I need to make a water bath and keep it on 38°C with an Arduino.. I've been searching examples about the wiring. I need to have a temperature sensor mounted to an Arduino. That should activate or deactivate the heating element controlled by the SSR.

But I've been looking around.. sometimes I see people attaching resistors the SSR.. sometimes they don't. How do I know when to attach resistors and how to calculate them? (been a while since electronics class)

Many thanks

2

Most SSRs already have a resistor in series with the input (the input is the LED part of an optocoupler). If the voltage range on the input terminal says something like 3 - 30 V, you don't need one. Be sure to observe the proper polarity.