Search results

  1. Herschel Peeler

    xmas present: blinking ring

    Electronic Goldmine sells a lot of blinking LEDs. Among then are some that blink multiple colors. A ring would be a problem size wise. Not much room for a battery in a kid size ring. Maybe a necklace. Can you cast metal? Make the design you want out of wax. Put that in Plaster of Paris. Pour in...
  2. Herschel Peeler

    Beginner assistance

    Lots of ways to get from 12 V to 9 V. How much current do you need?
  3. Herschel Peeler

    555 timers

    Mail order companies should accept money orders. It sucks to only need a dollar or two of parts to meet a minimum order of $10.00 but you can usually find something you can use. Electronic Goldmine and Jameco Electronics are my favorites. DigiKey and Mouser tend to be oriented toward...
  4. Herschel Peeler

    Driver required

    Are you trying to substitute LED lighting for incandescent lighting using the same system? What you describe is hard to make sense of. Maybe if we had schematics to look at it might help.
  5. Herschel Peeler

    555 timers

    I don't buy many electronics parts from e-bay. You are probably right about price.
  6. Herschel Peeler

    Why is this LED not 20 Watts?

    I got my high power LEDs from Electronic Goldmine. They also sell suitable heat sinks and fans. I don't know what your LED is rated at for voltage and current so it is hard to say if your driver is correct. The seller seems unreliable.
  7. Herschel Peeler

    555 timers

    Don't buy them on e-bay. Electronics distributors are more reliable. Kameco Electronics. DgiKey. Mouser Electronics, Electronic Goldmine ...
  8. Herschel Peeler

    Why is this LED not 20 Watts?

    It looks like they were sold as a set and should be a match, but that does not appear to be the case.
  9. Herschel Peeler

    555 timers

    Most likely any commercial product built with an old DIP 555 is on the junk pile by now. Where are you at that a 555 is difficult to come by or expensive? You are state side? Are you a student or just a hobbyist?
  10. Herschel Peeler

    Frequency to Voltage Converter Help

    What IC are you using for the comparator. You are looking for a high out. Some comparators are open collector and do not output a high. Pullup resistors are needed.
  11. Herschel Peeler

    Need help - TIP122 transistor

    The TIP122 will have some drop across it, so the voltage to the motor won't be the whole 5 V. The value of the base resistor for the RIP122 depends on collector current divided by the gain of the tIP122 under those conditions. That gives you base current. Divide that into applied voltage minus...
  12. Herschel Peeler

    741 circuit amp wont turn on

    What does it take to light the lamp? Voltage? Current? The LM741 can't put out much current. And the more current you draw the lower the output voltage. What voltage in? Try it without the capacitors.
  13. Herschel Peeler

    Testing mAh of a battery?

    Attached is a pdf version of an Excel file similar to what I used the last time did a similar test. It is not a real representation. Battery voltage is measured every hour. Current is calculated. Amp-hours are calculated and summed up as you go along. Stop whenever you feel like it. I was...
  14. Herschel Peeler

    Testing mAh of a battery?

    Good observation. I use Excel and note batter voltage and current, calculating amphours on a per hour basis, then totally them as it progressed. When to stop? consult the battery manufacturer. How precise do you imagine the battery rating is? Is 10% an acceptable error? 20%? If you test four...
  15. Herschel Peeler

    Testing mAh of a battery?

    Set the battery up under a known load and see how long it lasts, You will find you get a different mA-Hr result at different currents. As a general rule for most common batteries figure an 8 hour life. Divide mA-Hr rating by 8 to calculate load resistance.
  16. Herschel Peeler

    Voltage on a white LED.

    Good. Our living room and bedroom lighting are warm white. Kitchen and working (sewing and electronics) areas are cool white, mostly LED. Color representation is needed in the working areas.
  17. Herschel Peeler

    Voltage on a white LED.

    Yes, 5,000K is "blue" If the objective is longest life you are correct.
  18. Herschel Peeler

    Modified meter lead for breadboards.

    There is ample room on the smaller breadboard to modify the variable voltage sources to various configurations. Most dual op amps would work. I just have a lot of LM358s.
  19. Herschel Peeler

    Voltage on a white LED.

    I acknowledge the error, know the difference and deserve the comment. :-)
  20. Herschel Peeler

    How can i add a LED with the same time as the buzzer where it will be flashing on and off.

    You can buy LEDs that flash on their own. Go to Electronic Goldmine. They flash, about 80 pps. Others flicker, random, like a candle. Others are multi-color flicker.
Top