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sinara-hw / Thermostat

2-channel temperature controller
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The fan cannot be controlled by PWM #115

Open thomasfire opened 1 year ago

thomasfire commented 1 year ago

In Thermostat starting revision v2.2 there is a fan, that is as explained in schematics, can be controlled by PWM through power supply. But I got explanations from SUNON suppliers, that the fan model mf35101v1-1000u-g99' speed can be controlled only by changing the input voltage, and PWM through the power supply is considered to be unsafe, and in the specification MF35101V1-1000U-G99.pdf on page 12 in paragraph 7 it is said DO NOT use power or ground PWM to control the fan speed. In their catalogue there is also stated that g99 model doesn't have PWM (p36-37) SUNON DC Brushless Fan & Blower(255-E).pdf.

P.S. during tests of possible solutions for fan control we found out that PWM through power supply actually works, but it is not an official way of doing this, as SUNON representatives clarified to us.

Possible solutions for this issue are either use another model/manufacturer, and/or change schematics. @gkasprow

gkasprow commented 1 year ago

This is probably due to a back-emf issue, which can harm fan electronics when power gets disconnected. We used a diode in parallel with fan terminals to prevent such damage. The best way is to use 3-terminal fans in the next revision.