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  1. BobK

    Need help with fet circuit

    EMF poisoning does exist, but it comes only from a very strong EMF source, usually the sun or a tanning booth. Bob
  2. BobK

    Power Supply Woes

    Check this out: http://www.ebay.com/itm/LT1083-Linear-power-Adjustable-power-supply-module-Board-7A-/141849276682?hash=item2106e0310a:g:R1cAAOSwwE5WaRsm 7A capable. You could replace the adjustment pot with a combination pot and resistor to get the 3-8V range you need. Bob
  3. BobK

    Need help with field effect circuit

    Duplicate thread. https://www.electronicspoint.com/threads/need-help-with-fet-circuit.277429/ Bob
  4. BobK

    Help! Transistor radio converted into amp

    Not likely in a mains powered transistor radio. The mains are most likely only connected to the primary of a transformer and after that it is all low voltage. Just don't tinker with it when it is plugged in. Bob
  5. BobK

    Power Supply Woes

    Yes, an NPN transistor would be turned off as shown. A PNP transistor would act as a forward biased diode, shorting out the regulator. So you probably have a PNP transistor acting like a diode and no voltage regulation. The transistor would get hot. Bob
  6. BobK

    Volts to ohms for fuel sender

    With 10Ω you get the smallest voltage which is the fewest bars on the display. Bob
  7. BobK

    Need help with fet circuit

    Do you mean you want to power the LED from the antenna, or is the LED powered by another source and is only an indicator of the presence of RF. And why do you think you need a FET for this? Bob
  8. BobK

    Light Bulb Technology?

    Interesting idea. Blink the light off when we are blinking. Doesn't work well with 2 or more people in the room, though. Bob
  9. BobK

    Negative Voltage - Theory Question

    Look at it this way. Your car probably has a negative ground chassis (unless it is very old). There is a 12V battery with the negative terminal connected to the chassis. The positive terminal will be +12V from the chassis. Now add another 12V battery with the positive terminal connected to...
  10. BobK

    Why drop in voltage in this circuit ?

    Yep, I thought of that, but didn't know which so I just drew the always on schematic. Bob
  11. BobK

    Why drop in voltage in this circuit ?

    Here is what Chris is suggesting:
  12. BobK

    Amping low-current high-voltage (>300 V) RF (DC-100 MHz) with op-amps?

    Dave, I think he is talking about the DC to DC converter for the power supply. Bob
  13. BobK

    IR remote for android

    It occurs to me that the wiring between the left an right channels is probably done intentionally. Then, if you put out complementary signals to the two channels you can get twice the voltage difference you would get from either channel to ground. Pavle, can you point us to where you learned...
  14. BobK

    Wireless sign

    If you just want to light it momentarily, using the guts from a wireless doorbell might be just the thing. Bob
  15. BobK

    How to link a specific sound to a car healight switch

    A computer motherboard is a bit of overkill. There are modules that will play various MP3 sounds at the push of a button. A little bit of glue logic between the light switch and the module could cause it to activate one sound when going up and another when going down. Bob
  16. BobK

    IR remote for android

    Soldering then between the left and right channels does not sound right to me. They should be between one channel and ground. Edit: And I am still not sure how well this would work. Bob
  17. BobK

    Interfacing between Little and Big endian

    Actually it goes back further than that. Digital was little endian and IBM was big endian before Intel existed. BTW, I was the developer who prototyped this product, and made over 1,000,000 lines of customer code from PowerPC chips, which assumed big endian, run on Intel chips via...
  18. BobK

    User friendly GUI for modifying PIC program

    And the users have the capability of assembling a file and programming the chip? Bob
  19. BobK

    Space Heater Mod Project

    Wow, it is good to see someone actually listen when we tell them a project is dangerous. Most just get arrogant and insulting. Bob
  20. BobK

    need 10 volts from a power bank

    Look for a DC to DC boost converter. They are dirt cheap on Ebay. Bob
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