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  1. P

    Induced current in a coil

    Use a magnet and magnetic reed switch.
  2. P

    Audio files on a chip

    If you're willing to record your own audio file, you might want to check ISD chips. Some have inputs you simply ground for individual sounds to playback and some are programmable for use with a microcontroller. At work we use them both.
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    4017 Different LED count

    I believe the 4017 only counts up and returns to 0. A microcontroller, such as a PIC, can be programmed to do what you want and eliminate the need for a 555 in the process.
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    Cleaning a DBX Eq?

    I have sprayed individual sliders from the front and never had a problem.
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    LED resistor value/voltage doesn't make sense

    The digital multimeter is OK. Yes you must measure the voltage with the LED connected. I'm sure your LED will not light with a 47K resistor feeding from 5V. We have extremely bright LED's at work and to make the brightness "normal" we use a 2.2K resistor.
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    Chip ID on Hunter water controller

    Yes it looks like a microchip part made specially for the output module. It's probably a pre-programmed PIC. If it is bad, I think your only hope is another from the manufacturer. By the way, your R15 is missing. Did it fall off or intentionally left off by the manufacturer?
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    Pioneer SR60 Reverb not working properly

    Try to determine if it is mechanically intermittent by gently tapping parts on the circuit with the handle of a screwdriver. If not, get a can of freeze spray and spray individual parts to cool them. If the display comes on, you just found the perpetrator.
  8. P

    Marantz 4300 right channel intermittent and distorted

    Before you do anything, clean all the switches and controls with contact cleaner. If you see any PC mounted trimmer pots, give them a blast too, without turning them.
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    Tumble Dryer with No Heat Generation?

  10. P

    Possible new job. Looking for advice.

    How did it go Martin?
  11. P

    Marantz SR 63 static noise on left channel

    Before doing anything, clean all the switches and controls.
  12. P

    Power Supply Leads question

    Question #1 I don't have a clue. Question #2 yes. You hold them with 2 fingers and use your thumb to push the middle. Out of the end comes a hook that you clip onto your wire or circuit.
  13. P

    Tektronix 7514 scope vertical noise on display

    Before doing anything, clean all switches and controls with contact cleaner. Give the PCB mounted trimmer pots a blast also.
  14. P

    Tape speed

    Back in those days I was told that manufacturers set the speed a little fast to compensate for the normal slowing of the motor with age. Also if you make your own recordings with a machine running about 1.5% fast and played back on a machine not running 1.5% fast, it will be discernible.
  15. P

    Tape speed

    Trust me, I used to repair tape decks. A thicker belt will not fully descend into the groove of the motor pulley and change the "gear" ratio. As for speed adjustment, I used a 1KHZ test tape and a frequency counter. Believe it or not, the "norm" is to adjust the playback frequency to 1015 HZ.
  16. P

    Tape speed

    The thickness of the belt does have an effect on motor speed. When looped around the motor pulley, a thicker belt will effectively increase the diameter of the pulley and increase the speed. Some tape deck motors have a speed adjustment on the back. Look for a small hole with a trimmer resistor...
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    MOSFET 12VDC Relay?

    Question: I haven't followed this thread from the beginning but if you're using a switch to turn on a MOSFET to turn on a motor, why can't you just use the switch to turn on the motor?
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    Simple JFET Switch Question

    Perhaps the quickest way to achieve that is to have the mosfet turn on a relay or a smaller fet to turn on a PNP transistor with the collector feeding B+ to your circuit.
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    Simple JFET Switch Question

    I use this circuit frequently. This mosfet is rated 55A and can supply 2A without a heatsink.
  20. P

    Cell phone detector circuit

    Puzzling to me is the 1uF to ground from the antenna. Wouldn't that cut the RF?
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