Search results

Search Forums New Posts
  1. BobK

    multi direction dc motor

    sherjan, Only if you have dual supplies. A 4 transistor H-bridge does this with a single supply. Bob
  2. BobK

    AC to transistor in tuner circuit

    If you are familiar with microcontrollers, I would use a dsPIC to do this. All you would need is a crystal, an opamp or two for a mic preamp, the dsPIC and a few resistors and LEDs. The rest is software. Bob
  3. BobK

    multi direction dc motor

    How about letting us know what you changed to make it work fine? bob
  4. BobK

    How to increase gain

    Take out the capacitor - resistor between the output and pin 1 and connect the 10uF cap between pins 1 and 8. This will give you a gain of 200. If that is too much gain try a resistor in series with the cap of around 1K or lower. Look at the datasheet for exmples of different gains. Bob
  5. BobK

    ****ing speakers, how do they work

    As others have hinted, you would probably have to replace both the speakers and the amp. If you just want to use it for speakers for your MP3 player, I would take out the entire insides put in a new speakers and amp. It looks like the speakers are proabably around 5". You can get decent...
  6. BobK

    PIC16F648A simple function test, HELP!

    Pin 1 of the PICKIT should be going to pin 4 (MCLR). Also place a 100nF ceramic capacitor between Vdd and Vss near to the Vdd pin. Bob
  7. BobK

    DC LED circuit question..?

    When you plug a lamp with a 100W bulb (~1 Amp on U.S. 110V) into an outlet that can provide 15A does it blow up the light bulb? The current rating of a power supply is only the maximum that it can supply. The actual current drawn is determined by what you connect to it. So yes, it is safe...
  8. BobK

    Help with PCB design... I'm becoming insane! Please help!

    PCB CAD packages have the capability of creating your own components. This is what you have to do for anything that is not in the library. Look through the documentation for your software to determine how to do this. I tried Eagle and found that facility very confusing. I have also used the...
  9. BobK

    multi direction dc motor

    That should have worked fine. Did you try measuring various voltages and currents to try to diagnose the problem? Bob
  10. BobK

    Mono to stereo

    You can safely connect both left and right PC sound inputs to the same signal. Bob
  11. BobK

    electric bike

    Keep us updated if you pursue this, I might still want to build one myself (though not at this time of year, we just had our first winter storm! Bob
  12. BobK

    electric bike

    I have actaully thought about this a little, but never went beyond thinking how cool it would be to build. I see no reason why it could not be done, and I was inclined, as you are to consiider the direct drive approach. My thoughts were to have magnets mounted to to the underside of the wheel...
  13. BobK

    ceramic capacitor

    Show us your circuit. Bob
  14. BobK

    need help or advice for constructing a powerfull signal generator.

    In my first post, I was thinking only about the electronics. Putting sub 20Hz sound into a small closed box has it's own problems. Basically the box is much smaller than the wavelength, so you are not really creating sound waves that propagate, it is more like you are rapidly changing the air...
  15. BobK

    need help or advice for constructing a powerfull signal generator.

    No expert on this, but here are my thoughts. 1. I would be very skeptical about the 1000W ratings on your sub-woofers. This market is notorious for over-rating equipment. I doubt that they will handle anything like 1000W continuous. 2. To get 1000W into a 4 Ohm speaker, you need 63V RMS or...
  16. BobK

    double the voltage half the amps...

    Actually it is a boost converter that he is looking for. A buck converter lowers voltage. Bob
  17. BobK

    Urgent Help needed to get output of ac 5v 400hz frequency and current 500ma

    Thanks, Resqueline, but please do jump in with your own suggestions, I am an amateur. Some useful links: http://en.wikipedia.org/wiki/Phase-shift_oscillator http://en.wikipedia.org/wiki/Wien_bridge_oscillator http://www.national.com/mpf/LM/LM384.html#Overview Bob
  18. BobK

    Urgent Help needed to get output of ac 5v 400hz frequency and current 500ma

    Thinking about this some more. I think your best bet would be to build a separate, low-power osciallator, then feed it's output into an LM384 5-watt audio amp IC. You could then use the volume control to set the output amplitude, which might be tricky otherwise. The simplest way to make a...
  19. BobK

    Digital Controller to High Voltage

    Don't be insulted if this question sounds stupid, but when you used an external voltage to drive the program pin, did you also connect a common ground? Bob
  20. BobK

    Urgent Help needed to get output of ac 5v 400hz frequency and current 500ma

    This is the simplest circuit I can think of to do the job. Anything else would most likely be more difficult. You are not going to find a tried and true circuit to do what you want. Bob
Top