Search results

Search Forums New Posts
  1. BobK

    One-dimensional velocity sensor

    Interesting reading, thanks Steve. Bob
  2. BobK

    18dec to 5bin converter

    Well, that is a different problem than you originally posted. Your circuit will not work If more than one switch in on. Are you talking about 18 switches, which can all be in either state at any time? Or are you talking about a keypad where you expect one key to be pressed at a time? If...
  3. BobK

    Magnet coil help (turns, gauge, for coilgun)

    A 74HC04 should work fine for you, six inverters on a chip for $0.15 switching in 7ns at 5V. Bob
  4. BobK

    Simple Infrared LED Switch Help

    What is the voltage / current of the lamp you are trying to switch? This is important for deciding how to do it. You could use a 12V relay, but you would have to have a 12V supply then in addition to the 5V supply. Bob
  5. BobK

    18dec to 5bin converter

    Depends on what you mean by efficient. Speed, power, component count, board area, which is it? Bob
  6. BobK

    Magnet coil help (turns, gauge, for coilgun)

    Google "inverter" Bob
  7. BobK

    Current source OK until load disconnected

    Let me guess, something like this project should have been on the 'Jersey shore a couple of weeks ago? Bob
  8. BobK

    Wireless power transmission

    Wire-less inductors are hard to find. bob
  9. BobK

    Switching Regulator IC with Voltage Controlled Output

    Okay, I get it. I have done a couple of buck regulators with uControllers, but I did need to use a much bigger inductor that I would have with the dedicated chip running at that kind of frequency, and they were not doing much else. Bob
  10. BobK

    Correct potentiometer for a small speaker.

    That pot is outrageously expensive, probably because it is 2W. A standard 1/2 W pot would do for you. bob
  11. BobK

    Electronic whack-a-mole

    That's why the hardwood base come in handy, you hide the tubes under it. Bob
  12. BobK

    Simple Infrared LED Switch Help

    You could use the circuit as is, using the relay to switch your LED lamp. But if the LED is not using a lot of current (1A or less) you could just replace the BC547 with a higher power transistor and adjust the base resistor as needed, then place the LED lamp where the relay coil is connected...
  13. BobK

    Switching Regulator IC with Voltage Controlled Output

    If you have a microcontroller in the loop already, why use a buck regulator chip? The micro could perform it's function with a MOSFET switch added. Bob
  14. BobK

    Electronic whack-a-mole

    Aw, come on, Kris, you can certainly do it with tubes (valves). Bob
  15. BobK

    One-dimensional velocity sensor

    At 100 MPH at a sampling rate of 1500 samp / sec you will move a little more than an inch per sample. So a camera that views several inches of the road, say 5 or 10 should be able to work like a mouse for a car at that speed. Bob
  16. BobK

    Circuit for converting ammeter to voltmeter.

    blkfrd, If you really insist on doing this I would suggest a circuit with an op amp driving a discrete push-pull stage. The ammeter in series with a 1 Ohm resistor from the push-pull output to ground. You will need dual power supplies. The op amp can be configured with the feedback...
  17. BobK

    Wireless power transmission

    Well, 80% is in the same league as a typical wall-wart, perhaps even better, and that was at 1m, the efficiency is higher for closer distances. Intel is actually pushing for this technology commercially. I think it will take the form of a mat with the coil inside that you can just throw your...
  18. BobK

    Magnet coil help (turns, gauge, for coilgun)

    100 stages is probably not practical, I would start with 1 stage and work up to four or five before even thinking about 100 stages. As Steve said, timing these is not going to be trivial. Note that even with 1 stage the timing is important. If the current hasn't gone to zero when the...
  19. BobK

    understanding leds on ac

    Add up all the forward voltages of the LEDs. Subtract this from 170 (the peak voltage of the 120V AC line). That is how much voltage the capacitor has to drop. The voltage drop of the capacitor is: V = I Xc Where Xc = 1 / (2 * pi * f * C) Solving for C we get: C = I /...
  20. BobK

    Current source OK until load disconnected

    C.C., you have revealed an extraordinary new talent. You could be middle mangagement in any tech corporation in the U.S. of A. (approval by Dogbert notwithstanding). bob
View older results
Top