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  1. KrisBlueNZ

    How to set up a Beacon light to run from the mains

    Sorry if I freaked you out. Perhaps I overstated the case. I guess I'm very risk-averse when it comes to electrocution and fires! There was a nasty case in Australia earlier this year. But we have the "it'll never happen to me" mentality - and usually, we're right. So people still buy that crap...
  2. KrisBlueNZ

    Hi all!

    Hi there and welcome to Electronics Point :-) Tyger Tyger... Let me guess, you're a night person?
  3. KrisBlueNZ

    Need help building a basic digital counting circuit.

    2. Decoupling capacitors are typically 0.1 µF ceramic (disc or multi-layer ceramic). Yes, between VDD and VSS. 3. That's right, but have a close look at your schematic. The RESET node is connected to VDD, and the pushbutton is connected between VDD and VSS. You know how it should be done; you...
  4. KrisBlueNZ

    How to set up a Beacon light to run from the mains

    Those are switching power supplies, so to use them with halogen bulbs, you might need a small extra circuit as Steve described, to overcome the cold resistance problem, which could cause the power supply to fail to start up because of the initial overload. If you're using them with LEDs, that's...
  5. KrisBlueNZ

    Teac LPU190 with digital display not turning on

    OK, so the clock is informational only? In that case, it shouldn't be affecting anything else. Are you sure it doesn't have alarm or sleep functions? Is the Standby LED always illuminated when it's plugged in? But the pushbutton doesn't do anything? Can you trace the tracks from the Standby...
  6. KrisBlueNZ

    5 V to 1.7v (in SPI)

    Both SPI options on that controller have all signals going from the SPI master to the controller. The controller doesn't send anything back to the master. So you just need three or four downwards level shifters. If you're operating the SPI at 1 kHz, you can just use three or four two-resistor...
  7. KrisBlueNZ

    PC Speakers malfunction. Need help

    Can you measure the DC voltage across one of those two big electrolytics. It doesn't matter which. Hold the meter on them, then turn it ON and get the initial reading. Then see if it changes. Then measure the DC voltage across each of those electrolytics when it has died, and check the AC...
  8. KrisBlueNZ

    How to set up a Beacon light to run from the mains

    If you can find LEDs that are bright enough, small enough, and emit light sideways over the full 360° range, yes, I think so. (I assume that only the reflector rotates, not the bulb, right?) That would reduce the current consumption, avoid the cold resistance problem, and reduce the heating.
  9. KrisBlueNZ

    automatic doorbell

    Oh dear! circuitstoday's designs aren't generally very good. In this case they've forgotten the capacitor in series with R13 in the receiver. It will still work, as long as the temperature doesn't vary too much. The transmitter has a much lower output power than the 555-based design I suggested...
  10. KrisBlueNZ

    How to set up a Beacon light to run from the mains

    OK. So the motor inside can operate from either 12V or 24V, and it probably draws hardly any current. There are two bulb options: 12V, 55W and 24V, 70W. You can calculate how much current the bulb will draw by dividing its power rating (in watts) by the voltage: The 12V 55W bulb will draw (55...
  11. KrisBlueNZ

    LED control box

    Sure. I'll design a circuit that just has two switched 12V outputs. It's up to you what you connect across each output, within reason! Digi-Key do ship to the UK, but their shipping charges are pretty high. Yes, Maplin are a suitable supplier. If you promise to put your location in your...
  12. KrisBlueNZ

    Monitoring a swimmer's arm movement

    Unless you can get the swimmer to move a magnet on his/her arm within a few inches of the sensor every time, I don't think magnetic detection would be the answer. Perhaps a digital compass attached to the swimmer's arm, or a G sensor. Are you able to attach anything to the swimmer's arm? If...
  13. KrisBlueNZ

    Small telephone exchange...

    I think that's a great idea. A small exchange will already have most of the circuit functions you need. If you can get technical information on it, you may find it better to modify it than to start from scratch.
  14. KrisBlueNZ

    Suitable substitute part

    It looks like the only unusual things about the original Hall sensor are (a) it has a maximum output current rating of 400 mA, but I doubt that the connected circuitry would require this, and (b) it has two complementary outputs, but from the markings on the circuit board, it appears that the...
  15. KrisBlueNZ

    SCR activation question

    Daniel, that's not what he's asking. He knows how an SCR works. He wants to know... I'm afraid I don't know the answer either. My guess is that it wouldn't make any difference. Someone else here may know though.
  16. KrisBlueNZ

    florescent starter circuit collapsing power supply?

    OK, so the problem seems to occur if something is still warm when you try to start it up. Would it be useful to know whether it's the tubes or the ballasts that are causing problems when warm? You could try this: Disconnect the power to one ballast. Run the other ballast and its two lamps for a...
  17. KrisBlueNZ

    remote sleep

    I've used MSP430s extensively. They are quite a lot more powerful than PICs and AVRs. I'm not sure whether they're appropriate because I don't understand exactly what you want to do. Could you draw up a block diagram of your setup and annotate it with the features you want to add?
  18. KrisBlueNZ

    Need help building a basic digital counting circuit.

    Yes, a unipolar non-latching Hall switch. Those two Honeywell ones look fine. Re your design. 1. You can make the diagram a lot tidier if you use symbols to indicate connections to VCC and GND, you can avoid a lot of the long messy lines. Define the names of the positive and negative rails -...
  19. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    Good idea Steve. Also, I don't think there's any need to drive the -RST inputs of the 595s, and again I suggest that you drive the display's -FL input from the micro until you know you won't need it.
  20. KrisBlueNZ

    Dynex DX-L42-10A Intermittent Issues

    Right. It seems pretty clear from the schematic that there is no 32V supply in that set. Is there a "32V" marking somewhere in the set? If so, where? So you have all the supply voltages - 5V, 12V, and 24V - and the set isn't working? Is it still completely dead?
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