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From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Newsgroups: sci.electronics
Subject: Re: 555 timer duty cycle
Message-ID: <1876@bloom-beacon.MIT.EDU>
Date: Mon, 23-Nov-87 23:45:23 EST
Article-I.D.: bloom-be.1876
Posted: Mon Nov 23 23:45:23 1987
Date-Received: Thu, 26-Nov-87 21:53:10 EST
References: <9376@shemp.UCLA.EDU>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Organization: Independent Software Consultant
Lines: 16

In article <9376@shemp.UCLA.EDU> khayo@MATH.UCLA.EDU (Erazm J. Behr) writes:
>Is there any way to wire the 555 to get an "on" time of
>less than 50% of the cycle? (I know, "just add an inverter" -
>but I'd like to know if it can be done without adding extra
>active parts). Sorry for this, I'm sure the answer is in the
>library somewhere ...... 8-O

1) Don't use the open collector pull down to discharge the capacitor.
2) Run the charging resistor to Q. (you now hve a 50% duty cycle osc.)
3) To make the charge faster than the discharge add a diode with
   series-resistor in parrallel to the charging resistor.

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