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  1. KrisBlueNZ

    Choke for a NC motion sensor on a NO system

    Sure Jim. There are lots of knowledgeable people here who would like to help you with your electronics understanding and projects :-)
  2. KrisBlueNZ

    FM modulator light only and no transmitting

    I don't think that's a good idea. I think it would be best to keep the 0V rail at chassis voltage. I agree with Gryd3. Any pre-built solution will be cheaper and a lot easier than building your own circuit. And it will have the features you want - reading the Flash drive and broadcasting in stereo.
  3. KrisBlueNZ

    FM modulator light only and no transmitting

    Right, a 78M05 is fine for testing using a power supply, but if you want to put it in a car, a transistor will be better at withstanding the surges and spikes. It would be even better to add reverse polarity protection by inserting a UF4007 diode between the +12V from the car and the...
  4. KrisBlueNZ

    Choke for a NC motion sensor on a NO system

    With R1 at 320Ω, from a 24V supply, I make it about 72 mA (allowing 1V for the optocoupler LED). For 5 mA LED current, R1 should be about 4k7. Everything else looks good :-)
  5. KrisBlueNZ

    Is this switch safe? Dual 26650

    It doesn't seem like this is going over your head! You have the circuit design basically right. You have the cells connected in parallel. I didn't notice this before. That means the supply voltage is 3.6V. It's good for the coil, which obviously may need a LOT of current, but 3.6V gate-source...
  6. KrisBlueNZ

    Binary 1-wire switch status (closed/open) sensor?

    Have a look at the DS2408. It MAY do what you want. http://datasheets.maximintegrated.com/en/ds/DS2408.pdf
  7. KrisBlueNZ

    Multimeter fault UT136

    Could be, but not necessarily. I wouldn't want to guess. But you can't replace the chip anyway, and the meter is cheap. So just don't use the frequency range.
  8. KrisBlueNZ

    Multimeter fault UT136

    Yeah. I think the chance of finding a schematic for that meter is going to be about zero.
  9. KrisBlueNZ

    I need to time an AC outlet by seconds, or a break in a DC line

    Yes, and it's also easy to crack a walnut using a pneumatic drill... If you have one, and know how to operate it!
  10. KrisBlueNZ

    I need to time an AC outlet by seconds, or a break in a DC line

    Don't be afraid. It only happens once. Then you'll never go back. Bwahahahahaaaaaaa! OK. What kind of time periods are we talking about? Do you have (or can you get) a timer with a changeover output? In other words, it plugs into the mains supply and has two sockets on it, one for the filter...
  11. KrisBlueNZ

    MOSFETs that make you scratch your head..

    It will be able to drive the MOSFET fully to both supply rails, but it won't switch the MOSFET very fast, because the MOSFET has a high gate-to-source capacitance. Every time the MOSFET switches, it will dissipate a bit of energy while it passes through its linear region, as it transitions from...
  12. KrisBlueNZ

    SN74HC595N Shift Register Problem

    If you want a circuit that lights one out of four LEDs and advances with a clock pulse, that's not the easiest way to do it. The venerable CD4017 will do that, with any number of LEDs from 2 to 10. Alternatively you could use a two-bit counter driving a two-to-four demultiplexer, but a CD4017 is...
  13. KrisBlueNZ

    FM modulator light only and no transmitting

    Right. Both of those transmitters are mono, but I assume you want stereo. That adds a lot of complexity. And yes, the code is needed to understand the data format on the flash drive, and convert the compressed audio files into an analogue audio stream. This is not something that is practical to...
  14. KrisBlueNZ

    FM modulator light only and no transmitting

    That thing is a crystal. It is used by the microprocessor under the black blob as a source of constant frequency, so it can operate. No, that's not something that can be made easily. A lot of programming is required. There may be projects for this kind of thing. Try Googling those keywords.
  15. KrisBlueNZ

    FM modulator light only and no transmitting

    Most likely the problem will be in the IC that's underneath the blob of black stuff in the corner. I don't see a silver thing that looks like a capacitor.
  16. KrisBlueNZ

    FM modulator light only and no transmitting

    I agree. I guess there's something wrong on the main board. I don't know what to suggest.
  17. KrisBlueNZ

    Troll refuses help, prefers to insult moderators (was Video Generators video test signals)

    You realise that hevans1944 doesn't know you very well? Had you noticed how his answers were becoming more and more brief? Can you think why that would be? The reason for deleting threads (which I did not do, BTW) is to prevent other members, such as hevans1944, from WASTING LARGE AMOUNTS OF...
  18. KrisBlueNZ

    Low voltage Relays

    That doesn't mean anything. Have a look at Steve's resource on this subject: https://www.electronicspoint.com/resources/using-a-bipolar-transistor-to-turn-a-load-on-and-off.30/
  19. KrisBlueNZ

    MOSFETs that make you scratch your head..

    You may have damaged the MOSFET when you had an unknown voltage difference between the two 0V rails. MOSFETs have a very high input resistance and the gate insulation can be damaged by voltages as low as 15V; even lower on some with very small feature sizes. Fit a new MOSFET and add a 12V, 0.5W...
  20. KrisBlueNZ

    Project Logs

    I take the point about long posts being hard to edit. I find that the bugs in the post editor get more and more troublesome as the post length increases. I guess I would try to keep the article to a reasonable length, perhaps by pruning unimportant and outdated text out of it, rather than...
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