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  1. KrisBlueNZ

    Polish PNW-57 night vision goggles conversion

    OK. The enclosed part of the box should house K1 and K2, and C1 and C2. I expect it will contain part or all of the transformer. The transformer core will be made from either iron or ferrite, and could be quite heavy. I assume that section will also house the connection points for the cable...
  2. KrisBlueNZ

    Designing a Time Delayed Relay

    Either way is OK. The optocoupler circuit with the four diodes, in post #19, inserts a voltage DROP of about 2V in each direction. So the motor sees nearly all of the 220VAC. 220VAC corresponds to about 311V peak positive and negative excursions. The motor will see about 309V of each of those...
  3. KrisBlueNZ

    Polish PNW-57 night vision goggles conversion

    Is that a USB plug on the end of that cable? Just kidding. Can you open the box any further? I expect the high-voltage output components (two capacitors and two rectifiers) and the transformer will be inside the closed section. It's probably sealed for safety. But you'll need to get into it...
  4. KrisBlueNZ

    Designing a Time Delayed Relay

    Right. The optocoupler option can use some high-current diodes to provide a fixed voltage drop. A typical diode drops around 0.8~2.0V depending on the current and the diode's characteristics. So you break one of the lines to the motor and insert a circuit consisting of two high-current diodes in...
  5. KrisBlueNZ

    Next/previous switching a multiplexer

    -BORROW and -CARRY on the 40193 are outputs; you don't connect them to +V or GND if they're not used. Ditto for the outputs of the unused gates in the 4093. For the debouncers, typical values would be 10k for R11 and R12, 100k for R14 and R15, and 0.1 µF for C5 and C6. That's looking good now...
  6. KrisBlueNZ

    Polish PNW-57 night vision goggles conversion

    So the wire from the box to the goggles, is that a coaxial cable? An inner wire, with a layer of insulation around it, then a screen, then the outer insulation? I guess it just needs a low-current high-voltage DC supply, but I couldn't estimate the voltage. Can you take some photos of the...
  7. KrisBlueNZ

    How to wire this switch

    I get it. Sorry.
  8. KrisBlueNZ

    PSU Sugestions

    180 mA sounds very high for a simple low-power circuit like that. How did you measure the current? You have to measure current by breaking the circuit and connecting the multimeter across the break. If you connect the multimeter across the electrolytic, the way you do to measure voltage, you...
  9. KrisBlueNZ

    Need of a common ground???

    I'm talking about the resistance of the coil itself. If you want to make the relay pull in, you need to connect a DC voltage across the coil, equal to the rated voltage of the coil as marked on the relay. When you do that, a certain amount of current will flow in the coil, limited by the coil's...
  10. KrisBlueNZ

    PSU Sugestions

    There's no such thing as an op-amp that "needs" a single supply. Some op-amps are described as single-supply-capable but you can also use them with split supplies. I wouldn't worry about noise; the signal levels are going to be pretty high. If you're concerned about overloading the power...
  11. KrisBlueNZ

    Polish PNW-57 night vision goggles conversion

    Hi Timothias and welcome to Electronics Point :-) This is way outside my experience but there are a few things I can tell you. The first schematic is not a power supply; it's an oscillator based on a 555 timer IC. Its output connects to "VM3" which appears to be a voltmeter. I don't know what...
  12. KrisBlueNZ

    relay to power a 12v bilge pump

    OK. Yes, I think an LDO would be the best option. Farnell have four suitable devices. Listed in increasing price order: Texas Instruments LM2940T-9.0: http://uk.farnell.com/texas-instruments/lm2940t-9-0/ic-v-reg-ldo-9-0v-2940-to-220-3/dp/9493514 GBP 0.76; 1A output current; 0.5V dropout...
  13. KrisBlueNZ

    Need of a common ground???

    I assume the relay has a 5V-rated coil? To activate the relay properly, you need to apply the full rated voltage across the coil. The transistor should be in saturation so its collector-emitter voltage is as low as possible, leaving as much of the 5V supply voltage across the relay coil. The...
  14. KrisBlueNZ

    PSU Sugestions

    Is the top line on those ICs "074D"? If so they're probably TL074s. See http://www.njr.com/search/search_e.php?part=tl074&x=0&y=0 and the "7001" is probably a date code. I don't think the TL074 existed back in 1970 but I could be wrong. Or maybe JRC didn't use the usual yyww or wwyy date code...
  15. KrisBlueNZ

    Help please

    Phillips3236, what's happening with this issue? Did you see my post #23?
  16. KrisBlueNZ

    Motion sensor lighting with a difference

    OK. Do you know the current draw, or the rated power, of the strip light? Re the proximity sensor, it would be helpful if you could choose one and make sure it does what you want. Infra-red or ultrasonic would be suitable I think. It needs to run from 12V or some lower voltage. I'm going to...
  17. KrisBlueNZ

    How to wire this switch

    Terminals 5 and 6 are for the load, not any photosensor. The symbol on the front panel is a light bulb. I guess it detects the light level by monitoring the voltage coming in for the solar cell.
  18. KrisBlueNZ

    Next/previous switching a multiplexer

    Well spotted Harald! I agree the inputs need to be held at a known potential but I have never used series resistors with unused inputs on 4000-series ICs. I simply tie them to VDD or VSS. I agree with everything else you said though. If you have a reference that says otherwise, please post a URL!
  19. KrisBlueNZ

    Audio switch

    As for how to make the audio play, a simple solution might be one of those tiny MP3 players you can get for a few bucks. Jam the Play button down, take out the rechargeable battery, and power it from a USB charger that powers up when the mains to the light comes on. That could also power up a...
  20. KrisBlueNZ

    Need of a common ground???

    1. Yes, those grounds do need to be linked. Instead of just joining them together, I would use a ground symbol on all points that connect to the second ground - that is the transistor's emitter, the 7805's ground pin, and the connector pin. 2. The 7805 needs decoupling capacitors. See the data...
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