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  1. KrisBlueNZ

    Evening

    Hi Paul and welcome to Electronics Point :-) Thanks for introducing yourself.
  2. KrisBlueNZ

    Monster USB charger

    "Not even wrong" = doesn't make enough sense to be wrong, strictly speaking.
  3. KrisBlueNZ

    Monster USB charger

    That's not even wrong! The device will draw whatever current it decides to draw. The only way to force too much current into a device is to apply too much voltage to it (generally). That's right. Sounds like a good project to me. It's a good idea to have a separate polyswitch on each...
  4. KrisBlueNZ

    Repairs to fog machine

    It's possible that the control board doesn't simply produce an ON/OFF signal to the optocoupler. It may be using "phase angle control", as used in dimmers for incandescent lights. It might do this if it needs to vary the pump speed for some reason. Measure the voltage on the left end of R19...
  5. KrisBlueNZ

    Looking for wall adaptor power supply

    Set it to 9V and use a 7805 regulator to provide the 5V rail from the 9V supply.
  6. KrisBlueNZ

    Constant current power supply

    OK, here's my suggested circuit. The AC voltage from the mains transformer is bridge rectified by BR1 and smoothed by C1, which should be at least 10,000 µF. The thick lines represent connections that should be made with thick wire. For these wires, follow the topology shown in the diagram to...
  7. KrisBlueNZ

    Please help me identify this capacitor

    According to the Kemet data sheets (yes, the K symbol means Kemet), "WO" is the date code - the "O" means October, but "W" doesn't match any of the year letters listed on the data sheet, which cover 2009~2014, and "84" is described as an "internal code", which means that it means something, but...
  8. KrisBlueNZ

    Looking for wall adaptor power supply

    Do you want a bench power supply or just a wall adapter? You can get "wall wart"-type switching power supplies with output current around 1A here for less than the equivalent of £20; just get a 9V one and a 5V one, or regulate the 9V down to 5V. Cheap switching supplies can be unreliable; if...
  9. KrisBlueNZ

    Resistance of dark solar panel

    Right. If each panel includes a diode reverse-connected across it, then yes, you can just connect them all in series.
  10. KrisBlueNZ

    Please help me identify this capacitor

    Yes, 47 µF, 16V tantalum capacitor in SMT package. The K may indicate Kemet manufacturer. These are available in several sizes. Measure the dimensions and see which is the closest match. Size code C: 6.0 × 3.2 mm, 2.8 mm high Size code D: 7.3 × 4.3 mm, 3.1 mm high Size code V: 7.3 × 4.3 mm, 2.0...
  11. KrisBlueNZ

    Constant current power supply

    That's a very rough "current source". Only slightly better than a big resistor. What is the maximum anodising current you want?
  12. KrisBlueNZ

    Repairs to fog machine

    Good advice Steve. The optocoupler output you need to short out is pins 4 and 6. If you want to feed 5V into the left hand end of R19 you should first disconnect it from whatever it's connected to. It may be simpler to press the Manual button and measure the voltage.
  13. KrisBlueNZ

    Resistance of dark solar panel

    The bypass diodes would be connected in the opposite direction from your schematic. If you connect diodes that way, they will conduct when the panel is trying to generate voltage, and would short out the panel! (Or nearly short it out.) I have no experience with solar panels, but... If you have...
  14. KrisBlueNZ

    My first circuit, some questions..

    Feeding +24V into the 741 could damage it, and will at least disturb its normal operation, because it is powered from the output of the LM317 regulator, at about 17.2V. You're not supposed to force any pin of any IC beyond the voltages on its power supply pins except in certain cases like open...
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