Search results

  1. Y

    Need a cross reference for MOSFETS

    Sometimes its hard to see the forest because of the trees! No wonder these fail the MOSFET test! They test fine as back to back diodes. The two outside terminals connect to corresponding transformers. The + supplies are from the cathodes. I feel foolish for missing this...
  2. Y

    Need a cross reference for MOSFETS

    I traced the Drain connections to the corresponding output pins on the board connector, Pins 10,11,12 are the 5VDC output connections. Pins 2,3,4 are the 12VDC output connections. The filter capacitor correct voltage ratings confirm these outputs. So CRS101 (NF818) is for the 5V...
  3. Y

    Need a cross reference for MOSFETS

    Yes, I tried Google, even tried NT Quick Cross. Yes I am replacing the entire board, ordered new one this morning.. Still I would like to experiment with the old board.
  4. Y

    Need a cross reference for MOSFETS

    Y
  5. Y

    Need a cross reference for MOSFETS

    I need a good part number for a NF818 and NF840. These are MOSFET's for a switchung power supply.
  6. Y

    Join two power sources

    The confussion may be in the terminology. I tend to think of generators as DC producing devices. An Alternator produces AC, (Single or polyphase). My co-workers refer to our standby power sources as Gen-Sets, but they really are Alternators (produce 3 phase power when...
  7. Y

    VIZIO VW42L FHDTV10A LED TV DEAD

    This past weekend I came across a LED Flat Screen TV, curbside Naturally I could not pass up this opportunity to explore new technology. It is a model VISO VW42L FHDTV10A. Experience has taught me when something doesn’t power up, no lights, sounds etc., I look to the power supply. I...
  8. Y

    Does anyone recognise this symbol?

    It may be a VDR (Voltage Dependent Resistor). Bascly a thermistor. Used for supressing power surges. It has a high resistance when cold and decreases as current flows though it. Try placing a 100 watt incadescent light bulb in the circuit in place of the device. Tthe...
  9. Y

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    I didn't think it would be that easy, but I'm not complaining. I still need to increase the working voltage on the two capacitors, sometimes my battery system voltage peaks around 27VDC. Thanks guys,
  10. Y

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    I'm thinking R3, R4 are in series with the opto coupler transistor limiting the current through the transistor when t is turned on. Thank you for your comments. Eddie
  11. Y

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    I guess what your saying is I can change the relay to a higher voltage (higher resistance). I thought I would need to change R3 &R4 to higher values (same R3/R4 ratio) to maintain the same current through the divider, (less power loss?)
  12. Y

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    I guess the 7812 would be the simplest solution. I was hoping I could do it simply with adding resistors. Adam, Everything in my facility is powered by 24 VDC. Typically I use dc to dc converters to change 24vdc to other voltages needed. I cannot find a 24VDC telephone...
  13. Y

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    I built this niffty Telephone Ring detector with Relay Output from Velleman. It's designed to run off 12 VDC. I would like to run it off +24 VDC. Aside from changing the working voltage of the two capacitors, could I just double the resistor values or R3 & R4, and add a resistor...
  14. Y

    why we need Load resistor?

    Yes, more power will be delivered if the source impedance is lowered, this is why the load resistance in important. If you have a 5 watt source and you try to match a 10 watt load to it, it will burn up the source.. Its a case of having too little or too much. If the...
  15. Y

    why we need Load resistor?

    When working with vacuum tube power supplies, a bleeder (load resistor was often used as a load to discharge high voltage off the filter capacitors when the supply was turned off . A load is necessary to have power tranfer. Otherwise a circuit does no work, nothing happens. To get...
  16. Y

    Coil sitting in water for cooling, OK or NOT?

    I done some work with rf induction heating. We used 1/8" copper tubing to wind coils, then ran water through the inside. We packed the tubing with sand before bending to form. Sometimes we inserted steel springs and removed after bending.
  17. Y

    how long do the batteries last?

    I hope you experiment and share your findings. I read somewhere that most consumer type batterries are really rated at 1/10 A/hrs. A 10 A/hr battery doesn't really produce 10A for 1 hour, but more likely 1A for 10 hours. The more amps for a shorter period sounds more...
  18. Y

    Homebrew passive antenna coupler

    I bought a cell phone booster amplifier from Wilson. I also bought an inductive pickup/cell phone holder and a second pickup which is Velcro'd to my Verizon computer air card. Both devices deliver 3 signal bars more when attached. There has to be at least one bar of signal to amplify, but it...
  19. Y

    Strange behavior of a new battery in my cell phone

    I bought a cell phone booster amplifier from Wilson. I also bought an inductive pickup/cell phone holder and a second pickup which is Velcro'd to my Verizon computer air card. Both devices deliver 3 signal bars more when attached. There has to be at least one bar of...
  20. Y

    My Cousin Vinny (Run capacitors and motor direction)

    It's been my understanding that the rotation direction is determined by the angular hase difference between the two fields created by the two windings. The windings create two separate fields and the one field tries to catch up with the other causing rotation of the shaft. With...
Top