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  1. KrisBlueNZ

    Power Supply / Ciruit Noob help!

    Edit: Welcome to Electronics Point :) Your simplest solution would be to use a relay with a 120V AC coil, with its coil connected to the 120V AC from the garage door opener, and its contacts connected across the contacts of the wall switch. When the garage door opener is active, and sends 120V...
  2. KrisBlueNZ

    No Color. Black and White Picture

    Right, I couldn't find it either. What is the part number of the chroma IC? Do you have a data sheet for it?
  3. KrisBlueNZ

    Will an AOC - 23.6" LED HD Monitor work with my OLD PC?

    As long as they have compatible connectors, they will almost certainly work together. But for best image quality you need the graphics circuitry in your computer to operate at the native resolution of the monitor. The monitor's native resolution should be stated by the manufacturer. I Googled...
  4. KrisBlueNZ

    What is BV in LDO datasheet?

    Could mean "breakdown voltage"
  5. KrisBlueNZ

    No Color. Black and White Picture

    The individual R, G and B trimpots (often on the CRT base board) control the drive and bias to the red, green and blue cathode driver transistors. Adjusting them will change the colour of the picture but this doesn't have anything to do with the chroma circuitry; that's all much earlier in the...
  6. KrisBlueNZ

    White LEDs not working on red/white LED torch

    Hi Anthony and welcome to Electronics Point :-) Yes, if one LED fails it could cause the other one to fail to light as well. Normally LEDs are connected in series, not in parallel, since this ensures that the same current flows through both of them. (Connecting them in parallel is not...
  7. KrisBlueNZ

    -1kV pulse generator

    Fish, I think the reason Oseania doesn't want to use the ignition coil idea is that the pulse would be too long. The pulse rate would be no problem. The inductance of an ignition coil is probably too high, although using a smalller "condenser" value would help to get a shorter pulse with the...
  8. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    The mic is polarised. You have to connect it the same way round as before. Sorry I forgot to mention that. I'm not sure what to suggest. You could try returning both units to their original states (perhaps leave the power supply feed from the amp unit to the voice changer, but undo the other...
  9. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    Are you sure you connected to the right pin of the volume potentiometer? Not sure what else to suggest. Perhaps come back to it later and give it a once-over.
  10. KrisBlueNZ

    Alternative Energy.....

    I think Harald was thinking you were talking about "free energy". Alternative energy is real. Energy can be taken from the sun, wind, etc. "Free energy" involves taking energy from the earth's magnetic field, or from a perpetual motion machine, or some other kind of "over-unity" device.
  11. KrisBlueNZ

    Adjustable Power Supply

    A "12V 30A" power supply will produce 12V at its output, and can supply UP TO 30A. The amount of current it actually supplies depends on the load. So "30A" is a maximum rating for the power supply. Wattage is voltage multiplied by current, so again it depends on the amount of current flowing...
  12. KrisBlueNZ

    -1kV pulse generator

    Hi there and welcome to Electronics Point :-) I think a ferrite cored transformer would be a good starting point, driven by a transistor or MOSFET that conducts for a short time before the pulse, to build up energy in the core, then turns OFF to produce a large flyback pulse. You can connect a...
  13. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    OK, so the volume control on the amp unit has to be at the bottom of its range? That can be fixed by adding a resistor in the wire from the voice changer's output to the volume control pin. To make a significant difference, that resistor needs to be at least ten times the resistance of the...
  14. KrisBlueNZ

    LED blinking with switch

    Your circuit looks OK. What do you expect that code to do? The LED will not blink. It will just follow the state of the pushbutton.
  15. KrisBlueNZ

    op-amp help

    The best resources are the manufacturers' application notes and application guides. Texas Instruments in particular have a lot of very explanatory material. National Semiconductor had some good stuff too, but I'm not sure what happened to it when they were eaten by Texas Instruments. Try other...
  16. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    Try reverting to the original microphone for the voice changer. Disconnect the wire that comes from R8 on the amp unit, and reconnect the original electret condenser microphone to the 0V and input connection points on the voice changer.
  17. KrisBlueNZ

    LED blinking with switch

    Your diagram is too small to read properly. You have not made all of the changes I listed for your schematic. We are trying to help but it is quite frustrating when we repeatedly point out mistakes and you do not fix them. Make the changes to the schematic and post it in a readable form.
  18. KrisBlueNZ

    LED blinking with switch

    Those lines are not valid instrutions. The JB and JNB instructions require a label for the MCU to jump to if the condition is true. Your schematic in post #8 still has errors. R1 cannot be 110k beause that will not provide enough current to light the LED. Use something like 470Ω instead. R2...
  19. KrisBlueNZ

    LED blinking with switch

    The 8051 uses "quasi-bidirectional" I/O. If you want to use an I/O pin as an input, your firmware has to set it high and leave it high. The external circuit can then pull it low and you can read it on the port register. Your firmware should never use the instruction CLR P0.0. As soon as you do...
  20. KrisBlueNZ

    LED blinking with switch

    Is this a homework question?
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