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  1. KrisBlueNZ

    LED Flasher help.

    OK, I'm only part-way through the text, but I've got a lot written up, so it makes sense to post what I have so far. Here's the schematic: It's not really as complicated as it looks at first sight. The D-shaped things (2-input NAND gates) are only 1/4 of an IC each. And there are a lot of...
  2. KrisBlueNZ

    H-Bridge Circuit Design

    Hi Fish :-) I think there are a few problems with that design. 1. The transistors in the optocouplers seem to be connected backwards. They're NPNs, right? 2. I think it would probably be better to arrange the gate driving circuits so that the MOSFET will be OFF by default, and only turned ON...
  3. KrisBlueNZ

    Need help to fix motion detector alarm

    If the LED is supposed to light up when it's switched on (i.e. it's marked "Power"), and it's not coming on, the sensor is not the problem. Measure the voltage across the battery wires at the board. If there's voltage, bridge the switch terminals.
  4. KrisBlueNZ

    clap based volume control

    "Something contrasting"? Do you mean the different resistor values between the switches? The second one just uses preferred values (1, 2.2, 4.7 and 8, though 8 is not a preferred value). Neither of them is correct. I will explain below. Yes. All the circuits you've linked to so far are...
  5. KrisBlueNZ

    Need help with a PSU schematic

    Sorry, I can't help with JRC4012 or JRC4011 either. I thought perhaps they might have been CD4012 and CD4011 but those are 14-pin DIP packages, not 8-pin SIP. I guess if the power supply fails again, you'll know that D6 has failed, and you'll know that you need to use a higher rated zener!
  6. KrisBlueNZ

    Need help to fix motion detector alarm

    As Steve says, it's all standard stuff. If it doesn't power up at all, I'd suspect there's no power reaching the board, or the switch is stuffed. Install the battery and follow the wires from the battery to the board. Measure the voltage across them at the board, with a multimeter. If there's...
  7. KrisBlueNZ

    Need help with a PSU schematic

    OK. I would suspect C19, C22 and C14, and probably C17 and C21 too. C6 is not important. You could check them with a capacitance meter and an ESR meter to see whether they're faulty, or you could remove them and weigh them and compare the weight t the manufacturer's specification (if there is...
  8. KrisBlueNZ

    Need help with a PSU schematic

    I believe the SMPS is powered from 110VAC. The references to 250VAC marked on the schematic are just the ratings of the X and Y capacitors. I don't know why the main smoother is rated for 400V though. 200~250V should be plenty.
  9. KrisBlueNZ

    Need help with a PSU schematic

    Yes, C14, C19 and C22 are the important ones. If they dry out, they will not clamp the secondary voltage very well, and the zener will be forced to absorb more energy than it should. That's probably what caused it to fail initially. So it's good that you've replaced them. You used low ESR...
  10. KrisBlueNZ

    VGA to Sync on Green

    That's a pretty clever circuit but it's a bit naughty. It connects the output of U1D (pin 11) directly onto the green signal output from the VGA card. This could be the reason why it isn't working for you at +5V supply voltage. I've tried to do some research on VGA signals. It appears that the...
  11. KrisBlueNZ

    Need help with a PSU schematic

    The person who told you about the suitable replacement was me, in post #47. The zener that had failed, is that in the drain circuit of the MOSFET? If so, have you replaced all of the output capacitors? These can dry out and this can cause the zener in the drain clamp to fail.
  12. KrisBlueNZ

    Need help with a PSU schematic

    So you're going back to the original switching power supply for this mixer? Have you fixed it yet? What was wrong? Did we find a schematic for the original power supply?
  13. KrisBlueNZ

    Need help with a PSU schematic

    Yes it's possible, but it would need to be more than a tripler. At present you're adding the full-wave-rectified voltage from the full secondary winding (both halves) to the DC taken from rectifying one half of the secondary. If you want to work with only one half of the secondary, you'll need...
  14. KrisBlueNZ

    Capacitor replacement

    I wasn't disagreeing with you Dave. 56 µF IS a standard value; it's just not commonly used.
  15. KrisBlueNZ

    clap based volume control

    The rest of the circuit WILL "work" as shown, but the steps will not be even. There will be 16 volume steps, not four, and the LEDs will display a 4-digit binary number, not a one-of-four indication. If you can live with those restrictions, you just need a resistor across the audio output...
  16. KrisBlueNZ

    VGA to Sync on Green

    That circuit uses an LSTTL IC that should be powered from 5V +/- 0.5V. Use a 7805 three-terminal regulator (see http://www.fairchildsemi.com/ds/LM/LM7805.pdf) to drop a supply of 8V or higher down to 5V.
  17. KrisBlueNZ

    Capacitor replacement

    56 µF is not a common value. Digikey do supply them though; look at http://www.digikey.com/product-detail/en/EKZE630ELL560MHB5D/565-1720-ND/756236. Aluminium electrolytic capacitors generally have an initial value tolerance of +/- 20% or worse, and their values vary with temperature and age as...
  18. KrisBlueNZ

    Unstable latching circuit`

    Hi Rob_K If you want to control your circuit's sensitivity you might be better to go back to your original two-transistor circuit. I would suggest several changes to the circuit you posted in post #1 on this thread. Most of these were suggested by duke37 in post #6. 1. Change R3 from 100k to...
  19. KrisBlueNZ

    clap based volume control

    That is a terrible design. 1. As duke37 and Harald have pointed out, the clap detection circuit has problems. As well as the fact that the transistor is biased very heavily (so the signal must be extremely loud to get through), and the fact that each cycle of the frequency of the oscillations...
  20. KrisBlueNZ

    connection of a thermal sensor TC1047AVNBTR to the microcontroller MSP430F4618

    WHY? Can you explain exactly WHY you want to do that? And how would a simulation be useful to you? Yes, I would tend to agree with that. Depending on what you really want to do, you may need to simulate the entire MSP430 microcontroller, including its firmware! I will describe the circuit that...
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