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TV-Tech1, Technician
Category: Electronics
Satisfied Customers: 5316
Experience:  30 years servicing Tellys
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Firstly, I understand normal domestic electrics, but not electronics. I

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Firstly, I understand normal domestic electrics, but not electronics.
I have a 240v 'capacitance touch sensor' light switch, see The blurb states a minimum load of 3 watts. It works perfectly when used to switch a 15 watt light bulb on and off. However, I wish to use this switch to operate a 240v ventaxia bathroom extractor fan, rated at 4.3 watts and it doesn't work. If I connect both the bulb and the fan, they both work, but not the fan when connected on its own. The extractor fan is to be wired separately to the bathroom lighting, and I don't want to have to switch an additional light bulb on every time I switch the fan on. I'm guessing that I need to add some kind of capacitor or resistor into the circuitry, in parallel with the fan, that will act as a 'substitution' for the light bulb, ie, I don't mind using up a few extra watts to get the fan working - I just don't want it to have to be a light bulb. Incidentally, I've been advised that it's all to do with the 'resistance to neutral' of the fan and the bulb, but I'm non the wiser L. Please advise.
Logically, you'll be wasting 3 watts of power by adding a 18,000 ohm 3 watt resistor in parallel with the fan wiring, but it should trigger the switch to operate the fan. It'll only waste 3 watts while the fan runs. You should find a lower cost source than this, but it shows the color bands and the size resistor you require --
Customer: replied 2 years ago.

Ok - thanks Smile . I assume that if a 18,000 ohm 3 watt resistor doesn't trigger the switch, I should increase the ohm rating - maybe 24,000 ohms ?

No, reduce the resistance below 18,000 if iit doesn't trigger, it'll increase the wattage.
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Customer: replied 2 years ago.

Ok - thanks :-)

Customer: replied 2 years ago.

Hi: in conclusion, we have a high street chain store over here - 'Maplin' - like your 'Radio Shack'. They didn't have 18.000 ohms, but they did have 22.000 and 15.000, only a few cents each. I tried both, and either solves the problem :-) . Plus I managed to install the capacitor into the fan housing in such a way that the airflow dissipates the capacitors heat emission :-) . Very pleased with your advice and, hence, my results. Thank-you. Incidentally, the site asked if I would like to donate a 'tip', beyond the initial £20 fee, so I added a further £5, which I hope goes directly to you :-) . Thanks, ***** *****

Thank you very much. wish we still had Radio Shack, but they went bankrupt last summer.