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All resistors produce noise, depending on the temperature and bandwidth and resistance. Metal film resistors are probably close to the theoretical noise while carbon composition resistors are more noisy.

I posted a schematic on my website. You may have to copy and past the URL because Geocities does not allow links. http://www.geocities.com/russlk/vcnv.jpg <p>I forgot the divider resistors for .833 volts. They are connected from 5 V to gnd and are: 49.9K and 10.0K.<p>[ June 10, 2004: Message edited ...

I don't know anything about BIM2, but underwater communication is usually done at low frequency. The US Navy communicates with submarines at 10kHz.

It would be simple in DOS, but DOS doesn't know about USB. Windows dumps the print file to a spooler and processes it in background while you are doing something else. So, getting a Windows printer to do something simple like move one line, is not so simple.

The noise may be radiated to the antenna, check the grounding strap for the hood. Also, if you have old, leaky spark plug wires, these will make a lot of noise.

The MC14543B is a BCD to 7-segment decoder that can drive either common anode or common cathode. It is available from Digikey.

If both are running on 5 volts and the grounds are common, it must be a coding (programming) problem.

It has been a few years since I bought them, but NTE has 7 segment LEDs 1 inch high, part no: NTE3080.

It is actually a hall effect IC with an open collector output.<p>Allegro makes a sensitive linear hall effect, part number: UGN3503UA.<p>[ May 19, 2004: Message edited by: Russ Kincaid ]</p>

A normal motor has only speed control, you can't position it without a feedback system. Such a system is called a servo and is a field of study by itself. The stepper motor makes precise movements without feed back, so it is simpler, system-wise but the driving electronics is more complex.

The narrow end of the antenna is the front, but it will receive from the back also (just not so good). My Radio Shack controller has 3 terminals, see if you can find one of those.

Your 30 mHz scope is not going to be any use. If you have a receiver that will tune the frequency, you can hear the quieting that happens when you tune to the unmodulated carrier, or you can modulate it and listen for the modulation. If you just want to know if it is oscillating, measure the base an...

Most cheap metal detectors use the BFO system with a single coil. I doubt it would be sensitive enough for you. The 3 coil system is the best bet but I have no experience with it. There is another system called pulse induction but I tried that with no success.

If the load is under 1 amp, Linear Technology should have an IC, check out this URL: http://www.linear.com/prod/datasheet.html?datasheet=260

It seems to me that you are trying to make an open loop servo. That approach will be frought with problems. Is this motor going to oscillate back and forth (like a windshield wiper)? Or, will the motor turn and stop, holding a position? What I think you need is a position servo, but I need more info...