TTL homebrew CPUs

Chuck Guzis cclist at sydex.com
Tue Jul 10 12:26:56 CDT 2007


On 10 Jul 2007 at 11:25, der Mouse wrote:

> 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.

Cheers,
Chuck





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