I have a few consumer level air movers (Xpower) that have a 3 speed physical switch. Is there a way I could replace the physical switch with something that would interface with a microcontroller to change speeds? The manufacturer is not giving me much info other than the manual.

  • \$\begingroup\$ The easiest thing to do would be to use a stepper motor to physically control the switch. \$\endgroup\$ – crj11 Jan 8 at 15:02
  • \$\begingroup\$ Only if you are comfortable mucking about inside mains-connected gear, yes. Remove the switch, noting the connections. Measure the switch connectivity in all operating positions. Buy a couple of relays, low voltage DC operated coils, mains rated contacts, and configure them to provide the same connections. Drive the relays with a suitable interface, 24v coils and ULN2803 drivers are easy to use. However, crj11's suggestion is a whole lot less likely to electrocute you, and can be easily removed to revert to manual control, go for that. \$\endgroup\$ – Neil_UK Jan 8 at 15:02
  • \$\begingroup\$ Neil's approach works. Another might be to start out by assuming that the switch position (except perhaps "off") is monitored as a simple "signal." You can either try a voltmeter or else a 'scope and some imagination. If you can work out the details, you can design an approach that isn't quite so relay-heavy. I did this in the case of the IBM Electronic Model 85 typewriter in 1982. In that case, approaching 100 different signals generated by reed relays, some activated in combination, some not. Timing was also important then, too. Regardless, to design well you need to do some research. \$\endgroup\$ – jonk Jan 8 at 15:07
  • \$\begingroup\$ Thanks, these approaches make sense - after more research I found a competitors product with very similar 3 speed switch but their manual provides a wiring diagram, not sure if this brings any clarity? imgur.com/yycMKGP \$\endgroup\$ – MikeBman Jan 8 at 15:33

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