Author Topic: Thermostat upgrade  (Read 17 times)

SeanB

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Thermostat upgrade
« on: November 08, 2020, 01:30:28 PM »
Replaced this slightly elderly thermoswitch, using a more modern digital one.  Original is a 96x96mm unit, new one is a more modern 48x48mm unit, so a blanking plate was needed to fill the hole.

Original one from 1976, just slightly out of calibration, as turning the dial (broken in trying to get it open, though it was more or less so already) as the pointer was pointing at 120C, while the heater element was at 160C, a small 40C plus error. Strangely enough I can actually buy them as new stock off Aliexpress, and there apparently is a US company that refurbishes the old ones, there must be enough demand to still keep these running, but at a price. New is a bog standard BTC controller, a lot more capable, PID, multiple input types and 2 outputs in the package, as opposed to this old one with nothing other than some hysteresis, and a meter to show error in the setpoint and input. Had to glue that back, just to show, as the little bit of tape fall off years ago it would seem, and the meter movement was floating inside the case. No IC's in sight, just analogue discrete circuits and a real wound iron transformer to provide power for the electronics.