I had a problem with lightning, the spikes from a nearby flash would damage the PSU on my computers, modems and even the gate motor. I put in a choke on each leg of the mains wires, it was fitted in a box with plugs on it so that the box plugs into the socket and the other equipment plugs into...
I went to that site you gave there, and it is not much help at all. I assume one connects this unit to a parallel port, and enlarging the picture I see no transistors, but an opto coupler. They do mention that 20ma is needed, and there is an input for a separate power supply.
So here is a...
The voltage difference wont be a problem, but the polarity is! There are also different kinds of connectors, they look the same on the outside but the center hole is a different size. So if the pin is a thinner one and you have a connector with a bigger hole........(not a propper connection) (I...
I wouldnt be too prejudiced against IC's for todays circuits one uses two main things and that is op amps and 555 timer IC's. There are many circuits one can build around these two devices, and what is really nice about IC's is one can replace them without too much hassel if you use IC sockets...
As mentioned before the output from your UPS might not be a sine wave. To rectify this one could put a suitable choke in series with the fan and its electronics. The choke will round off ant squarish waves presented. The choke could be between 2 and 5mH and on the side of the fan a smallish cap...