square waveform (555)

Hello everyone,

Just liek to know if it is a normal thing that at LOW frequencies ( 15-25 Hz) that the output of a 555 timer is not exactly a square wave. At higher frequencies I get a perfect square wave (say between 50 and 300Hz). But at lower frequencies, the voltage when get to high, slowly decreases until the output of the 555 turns off. So usinf a 6v supply, instead of getting 6v high 0v low. I get 6v high,

5.99v, 5.98 ... 5.89, (there is a small slope at the high) then it goes low to 0v. I am using 50% duty cycle.

I hope I was clear enough thank you,

ken

Reply to
Ken O
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5.89V counts as damned close to 6V if you ask me. You're lucky to get that much with silicon, a 0.6V drop is more typical (and you'll find it under a stiffer load).

I don't know why it would drop. It could be real, some effect internal to the 555, a power supply issue (is +V varying by 0.1V as well?), or something with your meter, or how you're measuring it.

Tim

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Reply to
Tim Williams

Ok I put up a web page to show what I get on the scope:

formatting link

Everything is supplied by a 12v battery

I am using this cicuit:

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except for the resisitor to change the frequency.

Ken

Reply to
Ken O

Its staring you in the face right in the photo. Put the scope into DC coupling and check back.

GG

Reply to
stratus46

oook , thank you I feel dumb enough now

K
Reply to
Ken O

Sometimes the hardest things to spot are the most obvious ones.

Reply to
Mark Fortune

maybe your caps in your supply is not holding charge. test your supply voltage.

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Real Programmers Do things like this.
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Reply to
Jamie

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