square wave generator

and

ic

rms

Cheap pots come in values upto 1M, so would need caps of upto around

0.47uF. The issue I see is the need to adjust the value of both Rs together to cover the full f range, unless creative tricks are employed.

Yup. OTOH a 1 transistor osc uses less parts, and aiui the op is aiming for the most minimal osc.

NT

I don't know how useful these will be.......

They claim magical duty cycles here:

(fig. 9b)

mike

V and

ogic

terms

r

Sure, but he also wants a 50% duty cycle. MIT-style minimalism is a fine intellectual exercise, but is usually a total waste of time if you want something that works any time soon.

-- Bill Sloman, Nijmegen

I got another question, how come when I put the output of my 555 circuit on my scope, when I do DC coupling I see the square wave, but when I do AC coupling I see the positive peak then exponential decrease down, then negative peak, exponential increase up to zero, just like shown in this link, in the "Three Cascaded Delays" image

but, when I hook up my oscilloscope to a squarewave function generator, AC couple just shifts it down so the square wave is centered around the 0V line, and DC coupled shifts it back up where the low end of my square wave is at the 0V line.... it never distorts it to the voltage peak then discharge profile I see on my 555 circuit

my thought is that the AC coupling mode on my scope puts a capacitor in series with my signal to remove the DC offset, and since my square wave is mostly DC it's forcing it to zero.... maybe cause it's not buffered and some kind of loading effects.... in other words, I don't know what's goin on and would appreciate anyone who could shed a little light on it

just cause I see these positive and negative peaks on my scope, that doesn't mean their in my circuit right? I mean, it's only in AC coupling mode... they're not really there when my probe isn't hooked up to my circuit, are they?

much thanks

the scope's dc blocking cap's too small for 1-10Hz.

NT

Think about the AC-coupling capacitor size and the probe resistance _and_ the frequency of the 555 output. ...Jim Thompson

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Your scope is 1meg input impedance and most likely at such a low frequency the cap being used is too small. It's decaying much like any RC circuit would do.

Many circuits are built with these effects being desirable. ;)

Jamie