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Re: FODTRACK Interface



Hi Greg and Frank,

I built my own interface for the two rotors.  The TR-44 I use for azimuth
has a 500 ohm pot which gets shorted out as the antenna is rotated so a
constant 10 ma circuit will provide 0 to 5V for 360 degrees.  I kept the
analog meter because I wanted to maintain my stops at south but now I
have different priorities so I am building one with a digital panel meter
for a readout.  I use a pair of triacs driven by opto isolators which
were described in a 98 Handbook article by WD4FAB and also a few years
ago in the AMSAT Journal.

The elevation rotor is DC driven and I use a digital panel meter for the
readout in it.  It has a 1K pot in the antenna and actually has a 1K
resistor in series with the center tap but that doesn't seem to cause any
problem in the actual operation since the input to FODTRACK is a very
high impedance as is the input to the digital panel meter.

I have schematics and PCB layouts.  I had planned to write it up for
publication but that is another one of the "round-to-it" jobs.  Send me
your mailing address if you are interested in the data and I will send
you a copy.

73's de Jess - W4MVB
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