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  1. KrisBlueNZ

    Led Audio (Mic) VU meter

    Yes, the rest is negligible.
  2. KrisBlueNZ

    Led Audio (Mic) VU meter

    All good answers from Steve, as usual. I use an obsolete schematic capture program called OrCAD/SDT III for my schematics. I like it a lot and wouldn't want to use anything else, but it's quite ancient and there are lots of modern alternatives. See...
  3. KrisBlueNZ

    blink led

    Your schematic is still wrong. Here's exactly how it should look.
  4. KrisBlueNZ

    Timer switch help please

    No probs :-)
  5. KrisBlueNZ

    Timer switch help please

    Hi there and welcome to Electronics Point :-) The problem is that the 3-pin output connector is just a changeover switch. No power actually comes out of that connector. You have to feed power into it, and it will switch that power between two different circuits. You need to connect your 12V...
  6. KrisBlueNZ

    blink led

    You've removed the pushbutton, and C3, and the connection to pin 31. Put those all back like in your diagram in post #1. You don't need R1 though. Actually I think R1 was supposed to be connected to pin 9 but you connected it to pin 31 instead.
  7. KrisBlueNZ

    Help please Charger problem

    OK. Can you measure the resistance between the metal bits on the circuit board that the wires from the transformer plug onto. The photo in post #7, was that with the meter connected across the wires from the transformer? Can you plug the transformer back onto the board, plug in the power plug...
  8. KrisBlueNZ

    blink led

    Hardware errors: C3 should be higher than 1 nF. I suggest 100 nF. Add a pulldown resistor of around 10k from pin 9 to 0V. R2 must connect to VCC, not 0V. R2 must be a lot lower than 500k. For example try 470Ω. Firmware errors: You need to insert delays between the instructions that change the...
  9. KrisBlueNZ

    Help please Charger problem

    Yes, I had assumed that "resistance on the plug" meant the resistance between the two spade lugs on the board that the wires from the transformer plug onto. You're right that it's not clear.
  10. KrisBlueNZ

    Led Audio (Mic) VU meter

    That's a pretty poor design. There are so many problems with it that I don't want to start describing them all because I would be here all day. But the LM3916 is the right IC to use. The data sheet is at http://www.ti.com/lit/ds/symlink/lm3916.pdf. I STRONGLY recommend you use a different design...
  11. KrisBlueNZ

    Help please Charger problem

    If he's measuring a short between the two terminals that the transformer secondary connects onto, the bridge must be shorted. There's no need to measure the diodes individually. Yes, that one looks good.
  12. KrisBlueNZ

    Timing Circuit? Counter?

    Yes, that's all exactly right. The circuit will draw a few milliamps. Allow for 10 mA worst case.
  13. KrisBlueNZ

    Help please Charger problem

    http://www.digikey.com/product-detail/en/KBP02M-E4%2F51/KBP02M-E4%2F51GI-ND/2152670
  14. KrisBlueNZ

    Graphite painted cards and varying resistance

    What do you mean by "connected in parallel"? Do you mean that the two cards will be placed face-to-face? And how are you measuring the resistance? Can you describe what you're doing?
  15. KrisBlueNZ

    Adjustable Power Supply

    Computer power supplies are great for this kind of thing. But what output voltage range do you need? Generally people use the +12V output, and you will be able to vary the voltage on that rail somewhat, but not over a very wide range. You should be able to drop it down to 8.6V and 3A won't be a...
  16. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    It would be really good to know what the actual waveform is... Also, I suggest using some faster diodes in the oscillator. Also D1 is probably under-rated for current. D1 use 1N5404 or similar D3 use 1N4934/5/6/7, UF4002/3/4/5/6/7 etc D4 same as D3 or 1N5817/8/9 D5 same as D3 or 1N914/4148 D8...
  17. KrisBlueNZ

    Help please Charger problem

    It's normal for the secondary of a power transformer to measure less than 1Ω. I think the problem is that you measure less than 1Ω across the points that the transformer connects into. This probably means that the bridge rectifier (assuming that it uses a bridge) is short circuit.
  18. KrisBlueNZ

    N-type JFET LED CIRCUIT

    OK. I've moved this thread to the homework help forum. Please post homework questions there. So it's the N-channel JFET version of the circuit you're having trouble with. Starting with the gate drive. You need to connect a switch to the gate to change the JFET's state. You know that an...
  19. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    OK, that's good. If you can, get two sets of resistors. We can make a voltage divider using a high-value resistor and a low-value resistor, and we'll only need a few values to get a wide range of combinations. High-value resistors: 100k, 150k, 220k, 330k, 470k, 680k Low-value resistors: 470Ω...
  20. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    I think it's probably the resistor value being far too low. Any signal at all from your microphone is being boosted by the microphone preamp in the amp unit, and feeds almost directly into the input of the voice changer, which is very sensitive. See if you can find a resistor that's at least 100...
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