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  1. KrisBlueNZ

    How to prevent a capacitor from dischargeing back into my circuit?

    Have you chosen your capacitor? Six minutes is a long time for what you want to do. How about using a supercapacitor or a lithium coin cell, and a 32 kHz oscillator with the PIC running in low-power mode with periodic wakeup?
  2. KrisBlueNZ

    problem in 12v - 230v inverter

    No they don't. Have a look at those photos and see if you can tell which pins of the IC are connected to what. I can't. The second one also has a reflection from a flash which obscures a lot of the board. Read those two resources, try again, and check your pictures before you upload them. You...
  3. KrisBlueNZ

    problem in 12v - 230v inverter

    Gryd3 meant to link to: https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/ https://www.electronicspoint.com/resources/photos-with-phones.27/
  4. KrisBlueNZ

    problem in 12v - 230v inverter

    Those photos are out-of-focus and not close enough for us to check.
  5. KrisBlueNZ

    Designing a Time Delayed Relay

    I think that, plus that heatsink, will be fine. No, you don't need a mounting kit because you don't need electrical isolation between the device and the heatsink.
  6. KrisBlueNZ

    looking for a transformer

    Well did you look on Mouser and Digi-Key as Dave suggested in post #4? http://www.mouser.com http://www.digikey.com
  7. KrisBlueNZ

    Designing a Time Delayed Relay

    Yes there's a 0.6W "buffer". Yes, you should have copper on both sides with thermal vias, to improve heat dissipation. The tab is connected to the middle pin, i.e. the collector. In all TO-220 packages that I've ever seen, if the tab is metal and not specifically isolated from the component, it...
  8. KrisBlueNZ

    Designing a Time Delayed Relay

    Yes that one looks good. You need to derate the thermal resistance because you don't have free airflow but I think that will be fine.
  9. KrisBlueNZ

    Designing a Time Delayed Relay

    The maximum load from the circuitry to the right of the main smoothing capacitor, i.e. the relay coil and the switching regulator, is about 13.2mA. But that doesn't relate to the TIP29C. The TIP29C regulates that voltage rail by absorbing the power that comes in through the feed capacitor but...
  10. KrisBlueNZ

    Designing a Time Delayed Relay

    I assume it was, because the highest-rated device is rated for "±30A" and there's no reason to assume that it was designed to work with AC only. It continuously converts live-side current into an output value, so it can be used with AC and DC, and many of the applications for this device would...
  11. KrisBlueNZ

    Finally got me a 'scope - Have some questions

    Yes, 0.3Ω is pretty much a direct connection. I'm not sure what to suggest regarding checking your home earthing system. I guess, start by finding the earth stake and inspecting it visually. Then get a long piece of wire and attach one end to the stake, take the other end to the room with the...
  12. KrisBlueNZ

    How to prevent a capacitor from dischargeing back into my circuit?

    How would the PIC be able to measure the voltage on the capacitor if there's a reverse-biased diode between the capacitor and the input pin?
  13. KrisBlueNZ

    Finally got me a 'scope - Have some questions

    Not necessarily. The scope responds to signals that it measures relative to its 0V rail, which is connected to its case, and to the earth pin on its power plug. That is then supposed to be connected to the soil through the mains earth and the earthing stake at the house, and the house itself...
  14. KrisBlueNZ

    Designing a Time Delayed Relay

    My thoughts are that your thoughts are right :-) Any power dissipation in the current path through the ACS712 will be due to imperfect conduction, i.e. resistance. Not all of this will necessarily be perfectly "ohmic", i.e. it won't all have a constant value for R in V = I R or P = I2 R, (in...
  15. KrisBlueNZ

    problem in 12v - 230v inverter

    The original design, with brief description, is at http://www.electroschematics.com/9155/12v-to-220v-voltage-inverter/ That circuit should work. Double check every pin of that IC, one at a time. Upload a photo of your constuction.
  16. KrisBlueNZ

    Finally got me a 'scope - Have some questions

    Can you set up a permanent filter/notification on eBay? So if one comes up in future, you'll hear about it? It looks like the scope is picking up mains-frequency and other interference when you adjust the compensation trimmer. As morphingstar said, make sure you use a completely plastic...
  17. KrisBlueNZ

    CRT TV doesn't turn on

    Me neither. Not necessarily. A short between adjacent turns won't affect the DC resistance measurably. But it will affect the picture noticeably, and will stress the output IC. I would use strong, hard glue. Like that epoxy stuff that comes in two tubes with a resin and a hardener. But clean...
  18. KrisBlueNZ

    CRT TV doesn't turn on

    Nice work Wiru! Right! That will be because of the resistor(s) getting hot. Check under the board for dry joints. But you could check the diodes, especially VD308, for leakage. Desolder and lift one end, and measure the diode on the highest resistance range with the red lead to the cathode. It...
  19. KrisBlueNZ

    problem in 12v - 230v inverter

    Gryd3, thank you for flagging those duplicate threads with a link to the most appropriate copy (this one). devmania, a few seconds' thought should have been enough to tell you that posting the same question to multiple threads would only lead to multiple mixed-up replies and an enormous waste...
  20. KrisBlueNZ

    Finally got me a 'scope - Have some questions

    What's the story with your scope Steve? Did you fix it?
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