10 Jul
2007
10 Jul
'07
9:31 p.m.
From: "Chuck Guzis" <cclist at
sydex.com>
On 10 Jul 2007 at 11:25, der Mouse wrote:
You could also put a current source instead of a resistor.
This can be made with either a transistor and s few resistors
and diode or a jfet.
Dwight
_________________________________________________________________
http://liveearth.msn.com
But you get only tiny on times. Add another
resistor and use a larger
cap
and you can stretch the on time - indeed, with a
bit of care you should
be
able to get pretty much any duty cycle and
frequency.
Well, any frequency limited by the ionization time of the gas at any
rate. IIRC, that's something like 20KHz.
If you want to use a neon bulb (or a gas triode) as a sawtooth
oscillator (one of the more useful aspects of a relaxation
oscillator), you can improve the linearity of the charge ramp by
using a very high 500vdc or more) supply voltage and a large series
resistor.