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  1. KrisBlueNZ

    Diode I believe?

    First let's get the brewery jokes out of the way. So... do you have any daughters 18 or older? And would it be OK for me to visit and watch the system in action? It might take me a while to figure out what the problem is. Probably a few months, maybe longer. Is it possible that the glitches on...
  2. KrisBlueNZ

    Want to build a 2 event delay timer controller

    Yes, I can design a circuit for you that does what you want. I'm helpful like that :-) (Actually it's pretty simple.) Your description is good, and that's such a relief. We see some incredibly vague questions here on these forums. But I need to clarify several points. Correct me if I'm...
  3. KrisBlueNZ

    Please Hep with autobalancing motor project

    You may be able to do this using two power supplies, with no other components. It depends on what the "device which detects movement" is. It would be very helpful and save everyone a lot of time if you would: 1. Describe the parts of the project in detail. Give part numbers and URLs of data...
  4. KrisBlueNZ

    Help with inverter

    Youngfella. This thread is going round in circles. It's up to 11 posts already and we still know very little about what you want to do. If you want to see some useful answers, you need to start by DESCRIBING your WHOLE PROJECT. WHAT is the PURPOSE of the project? What are you going to use to...
  5. KrisBlueNZ

    Simply relay circuit - help please

    Well, check it out. Can you get access to the bottom of the board? Check that the fan header pins are properly soldered and haven't become loosened. If you can't get to the bottom of the board, wiggle the connector pins gently to see if they're loose. OK that indicates that the fan connector...
  6. KrisBlueNZ

    Simply relay circuit - help please

    It's nice to try to find the method you think will be best, but at some point you need to build something and try it out. You can spend forever going over ideas in your head, but without experimentation and testing, you have no real world knowledge to base your choices on, and you can run off...
  7. KrisBlueNZ

    Simply relay circuit - help please

    If the fan connector is 5V PWM then a transistor driver with the fan running from a 12V supply will just translate the percentage of 5V into a percentage of 12V. IOW if the PWM duty cycle is 60%, so you would measure 3V on the connector, then the fan will see 60% of 12V which is 7.2V. I'm not...
  8. KrisBlueNZ

    Wiring keyboard print

    Or use emery paper to sand the black stuff off the fingers along the edge of the PCB. Use antistatic precautions. Sanding can generate static electricity, which could damage the device under the black blob.
  9. KrisBlueNZ

    GCSE op amp help

    You need to give us a lot more background information. Dave asked you whether it's audio or RF you need. Now we know one more piece of information. But that's not much to work from. Give us a complete description of what you need. Be as thorough as you can.
  10. KrisBlueNZ

    SG3524 Help

    Thanks, I got them. I'll get back to you.
  11. KrisBlueNZ

    SG3524 Help

    I doubt very much that the unit is designed to run at 115V with 13VAC going to the main board. I've never seen a product that uses a mains-frequency transformer which supports 115VAC and 230VAC without a jumper or switch change on the transformer primary. Have a look for an AC voltage switch...
  12. KrisBlueNZ

    3V to high voltage inverter

    If you are starting from scratch I think a Royer oscillator is probably a much better idea than this crappy design. See http://en.wikipedia.org/wiki/Royer_oscillator Using Google you might be able to find some projects for a voltage inverter based on the Royer oscillator with details of how to...
  13. KrisBlueNZ

    3V to high voltage inverter

    I think my racket produced about 1.5 kV DC at the output. The only important component is the transformer. As I said, I don't know enough about the transformer to tell you how to wind your own. I can help with general suggestions but you will need to do a lot of experimentation yourself. What...
  14. KrisBlueNZ

    3V to high voltage inverter

    Fly zapper racket schematic Here's a circuit I reverse-engineered from a fly zapper racket I bought a while ago. I think this is what the original circuit (at the link you gave in post #1) was supposed to be like. Unfortunately I don't have any information on the transformer. I didn't want to...
  15. KrisBlueNZ

    3V to high voltage inverter

    Sorry to seagull this thread... I haven't read much of it. Just wanted to say to TedA that the "C547B" is a BC547B, a very common European transistor - NPN, TO-92, 45V, 100 mA, pinout the reverse of the 2N3904 (CBE not EBC). Also, that design is very strange. I had a look at the link in the...
  16. KrisBlueNZ

    convert switching-mode PS to stabilized PS?

    A few things to add to Steve's explanation. Any DC power source ideally provides a perfectly clean DC voltage. If you connect an oscilloscope across it, you should see a perfectly flat trace, at a vertical position that reflects the DC voltage. Any imperfection on that line is noise. Common...
  17. KrisBlueNZ

    Comparator inputs

    Resistance between pins 2 and 6 with the CTs connected should be the sum of the secondary resistances of the two CTs. Assuming each CT has a 100 ohm secondary, 200 ohms would be right. Pins 1 and 7 are the signals from the two CTs. If the CTs are connected in the same phase line, then pins 1...
  18. KrisBlueNZ

    SG3524 Help

    Pin 7 is the oscillator capacitor. I don't know why you tried grounding it, and I don't know why grounding it would make the circuit start working. Perhaps it forces the SG3524 output permanently ON; in that case, the board's output voltage would be more than 24VDC. I'm assuming it's a...
  19. KrisBlueNZ

    Simply relay circuit - help please

    I think so Chris. I had assumed it would be a 5V fan since he wants to run it from a 5V supply.
  20. KrisBlueNZ

    Simply relay circuit - help please

    OK, I thought you misunderstood. Right, 3V wouldn't be enough to start a 12V fan. I'd be concerned about it starting at 5V as well, once it has accumulated some gunk. I guess there isn't a 12V rail available?
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