Guru
Joined: 05/10/2019
Location: United KingdomPosts: 8964
| Posted: 09:17am 31 May 2026 |
I cheat. :-) STC-1000 temperature controller. £3.80 from AE including the necessary temperature sensor. Individual isolated Heat and Cool relays rated for mains. Available for 12VDC, 24VDC or AC mains supply.
I'm going to use two of these for controlling aquarium temperature. You configure the setpoint and the hysteresis, that's all you need. For heating only I will have the setpoint at 24.5°C and the hysteresis at 1°C. The heater then kicks in at 23.5°C (setpoint-hysteresis) and drops out at 24.5°C. The Cool contact will close at 25.5°C (setpoint+hysteresis) and drop out at 24.5°C. That makes it useful for either cooling fans or an overtemp alarm.