q:for the masters of electronics of the web a problem with ne555

hi I have a problem with ne555 I connect the ne555 in astable mode with (vcc=5volt) I connect pin 2,6&7 together with 2Mohm variable resistance & cap 220uf to get the maximum required time (~150sec)but when I shorted the variable leads to get the minimum required time ( ~.001 sec or less if it possible) I connect 1 ohm resistor series with the variable to catch my goal but ne555 is freezing with high level output my goal: when I short the variable leads ne555 give my as small as possible pulse ( pulse width .001 sec or less )

thank you for helps yar

It doesn't need a master to understand a 555, ask John Fields, but don't mess with Texas. I would suggest you read the datasheet first

have a look at figure6 where you find a minimum value of 1k. You will have to switch in different capacitors for shorter times. you can automatize switching with transistors (BJT or FET). Only this way you can resolve those short times on your pot anyway.

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ciao Ban
Bordighera, Italy

On Thu, 24 Mar 2005 06:12:16 GMT, in sci.electronics.design "Ban" wrote: snip

Texas or Texas Instruments?

I would have thought that TI could make a descent 555 by now

martin

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