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  1. KrisBlueNZ

    fuse

    If the lid is making contact with the battery terminals, the only way to protect the battery is to put the fuse INSIDE it! I think you're approaching this problem from the wrong direction.
  2. KrisBlueNZ

    Latching power circuit - expert critique please

    Hi there medic :) Sorry for the slow response. Your circuit looks pretty good. I wouldn't describe you as an electronics newbie! I have a few comments, most of which are probably just me being paranoid. I'll start with the simple ones. 1. Naming of VIN label I would call it VBAT or VBATT...
  3. KrisBlueNZ

    UPS charger output

    The UPS's battery charger is only used to recharge the battery after an outage, and to keep it topped up. You should not draw current continuously from the battery; the charger is not designed to deal with that. Use a separate, line-powered 12V power supply to power your loads while power is...
  4. KrisBlueNZ

    fuse

    If that's the only problem, just put some insulation on the inside of the lid. A sheet of plastic from a shirt box, a piece of fibreglass sheet like those used in microwave ovens, or something like that. That would be a lot quicker, simpler and cheaper than building up a whole circuit!
  5. KrisBlueNZ

    fuse

    I'm working on a circuit. May be a few days - I have some RL commitments ATM
  6. KrisBlueNZ

    Constant current power supply

    Hello and welcome to Electronics Point :) It would be helpful to know the operating voltage of the circuit. If you don't know, can you tell us the secondary voltage for the transformer. The output (anodising) current is determined roughly by the emitter voltage and the emitter resistance using...
  7. KrisBlueNZ

    Blowing a 3A fuse with an AA battery?

    Yes. Rechargeables (when fully charged) have a much lower internal resistance than zinc-carbon cells. And 3A is quite a lot of current to expect a little AA battery to supply. A 9V PP3-type battery certainly can't supply that much - rechargeable or not. Exactly. He would be more likely to...
  8. KrisBlueNZ

    Hey everybody!!

    Hi Diar and welcome to Electronics Point :-) Thanks for introducing yourself. I hope you find this site interesting and useful. Good advice from Adam. Also, Google relevant keywords like good introductory electronics books. There are many people out there who have made lists of recommended...
  9. KrisBlueNZ

    Resistance of dark solar panel

    Right. Currents don't add if you connect things in series. You can put a reverse-connected diode (rated for the maximum current) across each panel so that if either panel is in darkness, the voltage across it is limited to about -1V. Edit: I would be interested to see the results of any testing...
  10. KrisBlueNZ

    If the source voltage is the same as LED voltage, is a resistor necessary?

    LEDs aren't "rated" for a particular voltage. The best way to look at it is that you need to supply them with a certain amount of current (the light output is roughly proportional to this current), and this current will cause a certain amount of voltage (the forward voltage) across the LED. The...
  11. KrisBlueNZ

    V(rms) = V(ac) and V(ave) = V(dc), why?

    Thanks Adam :) No, that's not right. Your second diagram shows the formula for the absolute value of the sinewave, i.e. what happens if you bridge-rectify it. It doesn't show the shape you get if you square the value of every point on the waveform. The shape you get if you square half a cycle...
  12. KrisBlueNZ

    Designing a Time Delayed Relay

    I think we should use an "active zener" with a transistor dissipating most of the power. I suggest the BD237 in a TO-126 case, which can have a heatsink attached. I think that's the best solution. The circuit uses a "capacitor-fed" power supply. C1 passes current from the mains into the bridge...
  13. KrisBlueNZ

    V(rms) = V(ac) and V(ave) = V(dc), why?

    That's a pretty good explanation Adam. I'm going to exercise my pedantry and clarify a few points though. The RMS voltage of ANY AC WAVEFORM (regardless of its shape) is the voltage that, if it were DC, would produce the same MEAN POWER DISSIPATION, or the same HEATING EFFECT (which is the same...
  14. KrisBlueNZ

    Repairs to fog machine

    I guess you should check the cable from the board to the pump, but with those symptoms I think it's more likely to be the triac (Q5, BTA16) or the optocoupler that drives it (PHOTO2, K3023), or perhaps R25 (1k 1/2W). Most likely Q5 isn't triggering until quite a long way through the cycle, so...
  15. KrisBlueNZ

    Wireless trigger for LEDs and buzzers

    Not with light, no, I don't think so. But you could put the emitter and detector facing each other, one on each side of the net, but not in line with the widest part of the hoop - i.e. not half way between the hoop edge closest to the wall and the hoop edge furthest away from the wall, but...
  16. KrisBlueNZ

    T.v CE32G15 Toshiba

    No Comment
  17. KrisBlueNZ

    Repairs to fog machine

    Can you show us a close-up of the board covering everything between the AC mains input and the output to the pump?
  18. KrisBlueNZ

    Wireless trigger for LEDs and buzzers

    I don't think ultrasonic is a reliable way to detect a basketball falling through the goal net. I would use modulated infra-red light, with the emitter and detector-demodulator on opposite sides of the net (or perhaps the emitter hanging in front of the net, pointing back towards the detector on...
  19. KrisBlueNZ

    Help needed with charge circuit

    Your calculations are right. I think you're expecting more LED current than you need. 5~10 mA will give reasonable brightness if you use efficient LEDs. Have a look at this selection table on Digi-Key...
  20. KrisBlueNZ

    Hi everyone, new member

    Hi Canobi! Welcome to Electronics Point :-) Thanks for that fantastic introduction! Your motivation and attitude are inspirational, to me at least, and I hope we will be able to help you reach the goals you set for yourself :-)
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