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  1. KrisBlueNZ

    TO-220 heat sink electrical isolation

    Do you have electronics experience? How do you know that the wire is a "400V wire"? Is it possible that the wire is deliberately connected to the heatsink? Do the TO-220 packages have metal tabs? Are there insulating washers (e.g. soft grey, or brittle transparent, washers) between the TO-220...
  2. KrisBlueNZ

    High-voltage failsafe?

    LOL Duke :-)
  3. KrisBlueNZ

    Quartz crystal help

    duke37 is making a joke. The unit that you used, mhz, means millihertz. (Actually it should be mHz.) You corrected it in your latest post. 16 MHz crystals are widely available. Maybe not from Radio Shack, but from many other sources. Digikey, Mouser, Fry's are ones I know of in America.
  4. KrisBlueNZ

    Trotline Finder

    Things that glow in the dark might also attract more fish ;-)
  5. KrisBlueNZ

    How do you increase IR LED range?

    LOL! To the OP. Check out the references so kindly provided by duke37. This should give you an idea of what technology and effort will be required.
  6. KrisBlueNZ

    DAC output of microcontroller?

    From those specifications it's impossible to say. You're not technically violating either of the specifications, because the 100 pF capacitor is not connected _directly_ across the output and the 1k load resistor has no DC path to anything. But the combination of them does equate to some form of...
  7. KrisBlueNZ

    Microcontroller ADC reading?

    I agree with BobK. If the ADC uses a switched capacitor architecture, the actual DC current flowing into the input will be fairly low. (But as Bob said, check the specs.) What's important is that the input has a low impedance at AC, so that the spikes of current caused by the capacitor switching...
  8. KrisBlueNZ

    Battery Powered Power Supply

    It would also be helpful to see the original design. A link to the schematic would be enough. Dave Jones is a lot more knowledgeable than me, and most of the members of this forum. I trust his designs and I would only be interested in the differences between your design and his.
  9. KrisBlueNZ

    Quartz crystal help

    "12.0000B" is probably 12.0000 MHz "14.31818" will be 14.31818 MHz. This frequency was used in old PCs and is a multiple of the NTSC colour subcarrier frequency, 3.579545 MHz. "3579.545 KC" will be 3.579545 MHz, the NTSC subcarrier frequency I can't suggest anything for the others. Edit: Low...
  10. KrisBlueNZ

    High-voltage failsafe?

    You cannot predict the unpredictable. Accidents do happen. Things will happen that you did not anticipate. When you are working with potentially deadly voltages and currents, any risk is not worth taking... unless you believe that the loss of a human life (or intense suffering and disability)...
  11. KrisBlueNZ

    High-voltage failsafe?

    So you think because it hasn't happened to you yet, that it can't happen? That's an irresponsible and foolhardy attitude. I hope you are not ever responsible for another person's safety.
  12. KrisBlueNZ

    DC motor polarity reversal?

    The switching does need to be clean and sharp in order to reliably switch the latching relay from one state to the other. I've drawn up a Schmitt-trigger-based circuit to drive the first relay, K1. In the meantime you can use your existing circuit to drive it; just replace the collector load...
  13. KrisBlueNZ

    How do you increase IR LED range?

    LOL! Yes, what GreenGiant said!
  14. KrisBlueNZ

    DC motor polarity reversal?

    That circuit may not give a very clean switching action. A Schmitt trigger would be better. Something like the circuit at https://www.electronicspoint.com/question-mosfet-t258206.html#post1536817 but driving a relay. But in the meantime let's stick with the circuit you've got. What's the...
  15. KrisBlueNZ

    DC motor polarity reversal?

    Earlier in this thread you implied you were driving the circuit from a pushbutton. Now you say it's a 2N222 (I assume you mean 2N2222) transistor. What other information have you not given us? Provide a thorough description of what you want to achieve, and a circuit diagram of what you have so...
  16. KrisBlueNZ

    DC motor polarity reversal?

    A latching relay is a pretty simple way to do what you want. A lot less wiring than an H-bridge. I designed a circuit that uses a latching relay to control an antenna extender/retractor for another user. The diagram is at...
  17. KrisBlueNZ

    AND and NAND chips

    As Steve says, the four basic gates can be converted from one type to another by inverting the input(s) and/or output. Google "De Morgan" for more information. I'm not aware of any gate IC that explicitly has two or more different types of gates in it, either in the 74xx series or the 4xxx...
  18. KrisBlueNZ

    How to Connect TV (having RCA Video Input Port) with Laptop (having VGA Output)?

    The frequencies used for VGA display and standard PAL or NTSC TV sets are not compatible. VGA uses much higher frequencies for both horizontal and vertical scan. Also PAL and NTSC are interlaced while VGA usually isn't - at least, not at low resolutions. You might be able to set your display to...
  19. KrisBlueNZ

    How do you increase IR LED range?

    Use parabolic reflectors at both ends of the link with the LED(s) and photodetector at the focal point Use multiple transmitting LEDs, each with a separate parabolic reflector Use transmitting LEDs with a very narrow beam angle Align the transmitter and receiver very accurately Use LEDs with...
  20. KrisBlueNZ

    High-voltage failsafe?

    In that case, definitely not. Who told you that? It certainly can be lethal. It depends on what part of the body it flows through, and how good a connection you make with it. To be honest, unless you're talking about voltages less than around 30V, there is always SOME danger, and unless you...
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