[sdiy] Body capacitance problem?

[Dave Kendall]

Hi Dave.

On Mar 6, 2009, at 22:41, Dave Manley wrote:

> The input is high impedance.  When you touch it, you must be supplying 
> enough voltage to cause a trigger.  What happens if you ground 
> yourself before touching the trigger input?

Interestingly, the problem was lessened by touching ground, but didn't 
go away. A 1M pulldown resistor on the trig input did the trick solidly 
:-).
>
>
> If you have a scope, it is an interesting experiment to touch the end 
> of the scope probe with one hand (don't touch the ground), while 
> moving your other hand around near various things that emit fields - 
> transformers, florescent lights, power cords, etc.

Certainly is! the spotlight on the workbench made the scope trace go 
crazy.....
The scope also freaks out whenever I switch on the Kurzweil K2000 
that's quite near it, regardless of where the probe is. Connecting the 
probe's GND to 0V doesn't make it behave completely right either.
I guess the scope isn't shielded then...

cheers,
Dave



>
> -Dave
>
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