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.