[sdiy] 555 osc lock-up???

[Veronica Merryfield]

Use separate power supplies.

There is a rule of thumb - the 555 has two outputs, the output pin and the power supply. 

I think what happens internally is that the output stage partially crowbars the power rails causing a glitch. The newer cmos 555 do not exhibit this behaviour and are much preferred, unless of course you need the two outputs.

Veronica

On 2009-12-28, at 11:02 PM, peter edwards wrote:

> I'm building a circuit where two 555 oscillators are feeding to two inputs of a NAND network. When ever the frequencies get very close, the two oscillators lock together!
> Anyone know how to fix this??? I can use something other than a 555 if it would work better. ideally the circuit would be relatively simple. The output needs to be close to square (50% duty cycle) across the audio range of frequencies. I've been experimenting with the 40106 but it had the same issues.
> Thanks!
> -pete
> 
> 
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