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  1. KrisBlueNZ

    TO-220 heat sink electrical isolation

    Usually any fault with an SMPS like that will blow the fuse... after the main switching device(s) have blown. Are you sure there was a bare wire at 400V touching the heatsink tab of the transistor? Power supplies don't usually have free-hanging uninsulated wires like that.
  2. KrisBlueNZ

    How To Set Up and Meter A Variable Low Speed Blower

    Um... a motor with a fan attached to it? I guess you would put it in a tube and force the air through a thinner tube with a constant diameter, in which you would place an air velocity sensor (Google it). Then you would implement a feedback loop to control the speed of the motor according to the...
  3. KrisBlueNZ

    Make a LED Light with 22000 uf 350v Cap

    Are you sure they're 22,000 microfarads? A 350V capacitor of that value would be HUGE! If that's really what you have, well, they would be able to store a fair amount of energy. You would need a high-efficiency high-voltage switching supply to convert the 350V down to a few volts to suit the...
  4. KrisBlueNZ

    LED on AC Mains

    Hmm. Yes. I emailed them a while back asking if they wanted me to review their electronic instructables (for free) for obvious usability issues (after I saw a horrible design there for some voice-activated switch or something). I didn't mention safety because it didn't apply to that particular...
  5. KrisBlueNZ

    How to make 2 scoreboard with two controls?

    Where are you located? There's a field for that in your profile and it can help us to help you if you fill it out. Assuming you're in America, have a look at Digikey or Mouser. I'm sure you can guess their web site addresses! They will ship internationally too, but it's pretty expensive. For...
  6. KrisBlueNZ

    Trotline Finder

    How about using a GPS receiver as you place the lines, and making notes of the exact locations of all of them. Then you don't need anything special on the lines themselves. A GPS receiver can resolve X and Y positions to a metre or less, I think, now that SA has been turned off.
  7. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    Cool :-)
  8. KrisBlueNZ

    Electronics Mortuary

    It's possessed! Have you tried an exorcism?
  9. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    You should be able to get IC sockets from Digikey, otherwise Mouser, or maybe at your local electronic components shop. You can have static problems with any kind of floor (except a wet concrete floor, probably...) so it's always a good idea to wear a wrist strap and keep your circuit earthed...
  10. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    Re the LEDs failing, it was probably static damage. Blue and white LEDs are sensitive to static electricity and can be easily damaged. You should use anti-static handling procedures (wrist strap) with them. Re decoupling capacitors on the TC4467, see section 4.1 of the data sheet. It's looking...
  11. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK cool. Please post it on a new thread and send me a PM.
  12. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK, here's the modified circuit. I increased the 8V reference to about 8.7V because there's about a 0.7V drop in the emitter follower (QB). The emitter follower acts as a buffer with a reasonably constant voltage drop. The voltage at the emitter has a much lower impedance than the voltage...
  13. KrisBlueNZ

    Pulse Width Modulation Signal Stretching Thingy?

    I wouldn't be worrying about the indication yet. Measuring time intervals that short requires special techniques and knowledge. I don't have that knowledge; all I can do here is point out a few numbers and warnings. Light travels at 3x10^8 m/s. That's 300 metres per microsecond. That's one...
  14. KrisBlueNZ

    High Power Dual H-Bridge

    That looks good. It has bipolar transistor outputs so it will dissipate more power than a MOSFET outputs, but that's not a biggie. It's rated for 2A continuous output per H-bridge, so 4A continuous total. I didn't find it in my search because I limited it to 3A output or more.
  15. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    Looks good. You can add the part numbers for the MOSFET and the diode. Edit: You may find it easier to connect the 1k resistor to the pin 3 side of the 10 ohm resistor. It doesn't make any difference to the circuit, and the way you have it fits better with the schematic, but the other way may...
  16. KrisBlueNZ

    computer/amp interface

    If the problem is just too much signal, first see if there's a less sensitive input on the amp (e.g. a line-level input). If not, you can make an attenuator with resistors. If the amp input is mono, you can also mix the left and right outputs of the computer together in the process of...
  17. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    Yes, the NEC 2SK2498 looks good. It's specified for 13 milliohms maximum RDS(on) at VGS=4V. A standard 555 output may not go as far as +4V when running from a 6V supply. The 555's output stage uses NPNs and pulls low better than it pulls high. You could add a pull-up resistor, say 1k, between...
  18. KrisBlueNZ

    Sample and Hold, input voltage.

    They prevent the first op-amp's output from slamming against either rail. When the sample/hold switch is open, the overall feedback loop (from the first op-amp output, through the second op-amp and back to the inverting input of the first op-amp) is broken. Without those diodes, the first...
  19. KrisBlueNZ

    mini builtin amp for Bass Guitar

    There's not much room inside a bass guitar, even if you hollow out more of the wood. You might squeeze a headphone amplifier in there, running off some Lithium cells, but not a speaker amplifier (unless you provide power externally). If you want a practice system, it's possible to build a...
  20. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    OK, you want to be able to adjust your switch-off voltage down to about 1V. What about the maximum limit?
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