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Re: elevation screw jack

I'm in the middle of building a box that does most of this right now for 
the EME array W6OAL is putting together.  It uses a DPDT switch to run the 
actuator in and out and reads the pulses to provide position feedback on an 
LCD.  I'm adding the calibration routine tonight then we will integrate it 
to Dave's hardware.  It uses an Atmel 8535 (had a few on hand), a 2x16 LCD, 
a serial interface to a PC for the calibration run only, is written in C 
(about two pages of simple code), runs on 5V and is in a RS plastic project 
box.  Total cost will be maybe $40 in parts.
To make this interface with a rotor controller one would need to replace 
the switch with relays, add an RS-232/TTL converter (MAX 232 chip), and a 
DAC as noted below.  Should be pretty easy.
I don't plan to build one like that right now but will be glad to share the 
circuit and source code for this one with someone interested in building 
such a beast.


At 03:58 PM 01/20/2001 -0500, Doug Braun NA1DB wrote:
>How about this:
>A PIC-based microcontroller circuit that counts the pulses
>and generates the correct analog voltage with a DAC.
>A 16F863 or similar part would need only a few external resistors
>to do everything, and the software would be pretty trivial.
>The chip itself costs maybe $10.
>Doug Braun
>At 11:38 AM 1/20/01 , you wrote:
> >Hi ,
> >
> >I've bought a elevation screw jack for a good price but i don't know
> >how i should make a position readout that's accurate and analog .
> >(so i can use it on a tracking interface that recognizes a zero to 5
> >volts input)
> >The elevation screw has a end and beginning contact and has a contact
> >that gives pulses when turning the motor in or out.
> >
> >Any ideas???
> >
> >73 ON1DSE, jan                         mailto:cahill@dds.nl
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