Jump to content
Electronics-Lab.com Community

Trevcharl

Members
  • Posts

    5
  • Joined

  • Last visited

    Never

Trevcharl's Achievements

Newbie

Newbie (1/14)

0

Reputation

  1. 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 the box. One also has to put in a MOV to absorb high spikes, and there is a small cap on the mains side and one on the equipment side. This protects everything. We did not discuss the voltage of the fan, this could help if you used a MOV to protect it as well. If it is a DC fan then add a 10 ohm resistor in each leg of the supply and on the fan side put in a MOV rated slightly higher than the supply voltage. This would work for an AC fan as well. This will only stop spikes, and will not round off the square waves from the UPS. I have used inverters giving off square waves and this did not affect equipment performance, because the AC is rectified and smoothed and the transformer will round off the square edges. In a computer power supply the AC is rectified and smoothed, with a big capacitor, then is chopped at a high frequency through a small transformer down to the required voltage. A transformer is more efficient at a higher frequency, so you can see that square waves should not have that much of an influence.
  2. 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 criteria - you need power and you need a positive drive of 20ma to operate the relays. To test apply power to Gnd and a positive 5v to VCC. Use a 330 ohm resistor and connect between IN1 and VCC - relay number one should operate, the same for IN2 - relay 2 should operate. Conversely if the IN1 and IN2 is looking for GND connection then use the 330 ohm between gND and IN1 and IN2. From this you will know what the inputs require, and you can make up your circuits as specified below to make it work. That proves the unit is ok (You might need to measure the relay outputs with an ohm meter to see if they are working if you cant hear them operating) The computer you are going to use needs and output that can supply 20ma at 5 volts. Many outputs do not supply 20ma so one might need to use a transistor, the output line goes to the base the collector goes to IN1 or 2 via a 330 ohm resistor. The Emitter goes to GND that is if the 330 ohm resistor operates when taken to GND. (NPN transistor) If the relays operated when the 330 ohm was connected to VCC then a PNP transistor is used Emitter goes to VCC and collector goes via 330 ohm resistor to IN1 and 2. Any Audio driver transistor can be used, ask your supplier for a Audio driver PNP or audio driver NPN. Good luck.... Trevcharl
  3. 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 assume you have the small round power plug for the power like my tablet has) cheers Trevor
  4. 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! I designed a PCB for a dual op amp, that facilitates 20 different circuits. The op amp is a simple little device, for instance if you want an amp with a gain of 10 you will need 3 resistors and two caps. The gain is determined by the ratio of two of the resistors. One gets a "Power op amp" (TDA2003) that 4 resistors and 4 caps. One will have to scrounge around the websites for circuit diagrams, but if you get stuck contact me, I can email you diagrams, and pcb layouts too if need be. The very first thing you should be building is a variable power supply, once you have that done you now have a power source to test anything else you want to build. cheers [email protected]
  5. 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 of 47nf, voltage about 650. I seem my local spares provider sell a "Mains capacitor" which is a 450v unit. Remember the mains of 220v is actually the rms value, the peak value is around 330volts. Another thing that can cause malfunction is high voltage spikes. This does not cause the fan to burn out, but will break down any weak insulation points, seeing you spoke of "burn" is is more likely a consistent unusual supply that can do this, pointing to irregular wave shapes. Experiment with a choke.
×
  • Create New...