I have a small enclosure with 110VAC 120mm fan (about 0.2A); need it rigged to keep temperature to reasonable noncritical level for equipment. Had simple reed switch thermostat, so fed triac with it: fine, but fan is TOO loud. So tried simple diac-fired variable control; controls acoustic noise fine but AC noise is FAR, far too bad within enclosure, even with filtering that fit. So: I figure that I can make a zero-voltage-switching control either to set just the motor to a fixed level about half speed and keep the reed switch thermostat, or make a proportional ZVS control that includes temperature sensor. Actually, just any simple, electrically quiet way to reduce the fan to roughly half speed would do adequately, along with my triac/reed thermostat. Size and cost are important - can't need separate power for the control. Figure 17 in app note for AN3004 might do though more complex than I want (at: https://www.electro-tech-online.com/custompdfs/2007/05/AN-3004.pdf ) but neither part AN3004 nor MC33074A appears to be available. I'm not currently into programming PICs &c. So: what is the very simplest thing I can do, please? Thank you, all.
- kenne
- kenne