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Bypassing a on/off switch on desiccant dehumidifier

scottc6

New Member
Hi guys,

I’m trying to bypass an on/off switch on a desiccant dehumidifier. I want the dehumidifier to start up when plugged in and not have to press the on/off button. I have included a picture of the front and back of the circuit board. Please help. Can this be done? if so how?
 

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If button is held on and not released when powered up does humidifier start and stay running
with button constantly pressed ?

What is V on switch to ground when it its open ? And when pressed ?


Regards, Dana.
 
You can add a little 5V relay and wire in a 5v power brick to the mains power. Wire the 5v out to the coil on the relay. Wire the switch pins in the relay to each side of your switched circuit.

Then, once power is applied, the power brick usually has a short delay (0.5 to 2seconds) between the time the brick is energized until it delivers 5v power. That delay should be enough for your humidifier to start up and be ready for the switch to apply.

One condition, you'll have to make sure it works with the switch applied the full time or if you need to pulse the switch. If pulsing is the answer, then we need more circuitry.

Note, get relay that needs very few mA to stay in the "on" state so it doesn't overheat at the coil.
 
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