Re: [CAD_CAM_EDM_DRO] Re: 555 timer circuit

----- Original Message -----
From: <tom@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, May 22, 2001 1:45 PM
Subject: [CAD_CAM_EDM_DRO] Re: 555 timer circuit


> If it wouldn't hurt any feelings I would be happy to post a circuit
> that I designed using twin Voltage Controlled Oscillators (VCO) and a
> joystick from a computer. It has step and direction with speed and
> direction based on stick position. Sense inputs allow for limit
> switches and the cicuit has an adjustable "dead zone" of zero pulses
> around the center points on the stick. Ramp up and down are
> controlled. I put a rotary switch on mine to give three speed ranges
> from zero to 1000 pulses per second, up to zero to 15K pulses. I
> built the unit to be part of a manual control console and used some
> complex relay switching to select manual or computer control from the
> console. I've been working with computers too many years to
> COMPLETELY trust them! I only built one so I hard wired the circuit.
> I don't have a PC board designed.
>
> You can use a 555 as a VCO but it has a limited range without adding
> an external charge current source using FET op amps. I went this way
> first but could not get the 100:1 frequency ratio I needed. I will
> have to wait unitl I get home from work since the circuit is on my
> CAD computer at the house.
>
>
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