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  1. KrisBlueNZ

    Stage Line 500W amp repair project

    Yes. At least a dead Q7 wouldn't have caused any other problems.
  2. KrisBlueNZ

    Power Regulation Strategy

    Breadboard construction isn't suitable for a switching supply. Use stripboard or padboard, or ideally PCB. Layout is important and should be described in the data sheet or application note for the controller IC. What's the part number for the Schottky diodes you're using? What reverse voltage...
  3. KrisBlueNZ

    application of signals

    In my experience, it's closer to the other way round. Provided you find the right book or article. Try Googling with more specific keywords. It's a lot easier, quicker, and more reliable to find the right article(s) among all of the articles on the internet, by searching for relevant keywords...
  4. KrisBlueNZ

    Stage Line 500W amp repair project

    Yes.
  5. KrisBlueNZ

    a timing circuit

    So let me get this straight. If you disconnect the 100Ω resistor between C and D (in post #28) to isolate the phototransistor from the MOSFET's gate, you get voltage at C, which is high when the phototransistor is dark, and low when the phototransistor is lit by the LED? And when you connect...
  6. KrisBlueNZ

    Need help with electronic circuit (Make: Electronics Experiment 8)

    OK, here's a circuit that should work. It uses both sets of contacts on the relay - one to make it oscillate, and the other to light the LEDs. It needs an extra resistor, and a transistor. R1 and C1 determine the flash rate. If you use your 1000 µF capacitor for C1, it will flash fairly...
  7. KrisBlueNZ

    Audio Amplifier distortion issue

    Can you upload a photo or two of your breadboard layout?
  8. KrisBlueNZ

    Yamaha RX-V750 doesn't switch ON.

    Hi there. Sorry I haven't got around to replying to this question yet. I'll reply later today. I've deleted your repeat thread.
  9. KrisBlueNZ

    The input given to Piezo Speaker is an analogue signal or Digital signal?

    Yes, that's right. When the signal from the Ardino goes high, the speaker cone moves one way - let's say it moves outwards, towards the listener. When the signal from the Arduino goes low, the speaker cone moves the other way - away from the listener. If this happens regularly, each change on...
  10. KrisBlueNZ

    a timing circuit

    Oh, OK. I get it. So you took the 100kΩ resistor that was connected from C to Z, which I said wasn't doing anything, and you removed it from that part of the circuit. Then you replaced the 3.3 kΩ resistor with the 100 kΩ resistor. Now the circuit works OK. That's fine. As long as you get at...
  11. KrisBlueNZ

    Using $1 stereo amp in mono mode

    Great! I'm really glad you're happy.
  12. KrisBlueNZ

    a timing circuit

    I'm not happy with that fix. Changing the 100 kΩ resistor to 1 kΩ will reduce the voltage at C, but the voltage at C should swing over a wide range. It should be at least 7V when the phototransistor is covered up, and it should be less than 2V when the LED is pointing directly at the...
  13. KrisBlueNZ

    a timing circuit

    1. The LED may have been damaged when it was connected backwards, so if you haven't replaced it already, replace it. 2. If the voltage from C to Z still doesn't go below 2V with the LED shining on the phototransistor, try reversing the photoransistor to see whether point C goes any lower with...
  14. KrisBlueNZ

    a timing circuit

    OK, Joseph reversed the LED and has PMed me some new measurements. Let's keep the info on this thread now Joseph. 1. A-Z 8.61v 2. A-B 7.36v 3. B-Z 1.24v 4. C-Z 7.49v 5. Uncovered, C-Z 4.36 OK, those voltages are all good except #5. The way that circuit works is that the 3.3 kΩ resistor...
  15. KrisBlueNZ

    a timing circuit

    Joseph PMed me and said he has reversed the LED and is getting 1.24V across it. OK Joseph, can you repeat the measurements I listed in post #28.
  16. KrisBlueNZ

    Stage Line 500W amp repair project

    No, it's the point marked "~0V" in post #295, yes measured relative to T4. And the equivalent point on the other channel.
  17. KrisBlueNZ

    24V 3A output required from HP Z-book laptop.

    I second everything that Gryd3 said. Your load needs 24V at 3A which is 72W. It will have to come from a boost converter, which might be 80% efficient, so its input power will be 90W. That's at least twice what the rest of the laptop draws from the battery, so it will cut your run time to around...
  18. KrisBlueNZ

    Stage Line 500W amp repair project

    Fit the resistor fuses first and repeat the voltage measurements from post #295. Actually, just the base-emitter voltages on the positions for the four output transistors is enough, and the DC voltage at the output. If the base-emitter voltages are all less than 0.6V and the DC output voltage is...
  19. KrisBlueNZ

    Using $1 stereo amp in mono mode

    I would not expect that panning the sound hard left would mix the left and right channels together evenly. Check with a test signal that has audio in each channel separately.
  20. KrisBlueNZ

    sensor to detect soccer ball

    I guess one option would be a two-dimensional grid of beams of some kind of light, probably lasers pointing at photodetectors, with the beams in each axis spaced closer together than the diameter of the ball. You would need some pretty fast acquisition logic and some clever calculations if you...
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