one inverter oscillator

Ron H

Joined Apr 14, 2005
7,063
It has been my experience that when a design engineer uses the term "multivibrator" without a qualifier he is invariably referring to the astable form. The Jim Williams application note is good example of this. The original statement made by Ron is another.

In the trade, a monostable multivibrator is usually called a one-shot and a bistable multivibrator is usually called a flip-flop. Maybe that's the reason people say simply "multivibrator" when referring to the oscillating one.

The inventors of the oscillating multivibrator didn't call it an "astable multivibrator"... they called it a multivibrator. And they were the ones who coined the term. The monostable and bistable forms were later derived from that original multivibrator. This may be another reason people say "multivibrator" when referring to the oscillating one.

(Source: http://mysite.du.edu/~etuttle/electron/elect36.htm )

Given that this is the popular and widely accepted usage of the term "multivibrator" (outside of academia), Ron was right in stating, "An RC multivibrator is an oscillator." (Even if he now thinks he was wrong.)
Yes, you are correct in your tracing of my thought process (or lack of it - I suppose it was more of a gut reaction).
Speaking of one-shots, I have occasionally used a common circuit which I have dubbed the half-shot. I don't think it has another simple name. You can see it in the attachment. You will recognize it as simply half of a classic astable MV.
I don't claim to have invented this circuit. If you are in need of a pulse differentiator, and don't have any gate ICs available, it can be handy, as long as you don't need the trailing edge to be super fast.
Obviously, you can make a complement of this with a PNP.

I guess I just re-hijacked this thread.:eek:
 

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THE_RB

Joined Feb 11, 2008
5,438
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We seem to be able to say that something is or is not an an oscillator for instance but what is it that actually makes it an oscillator an oscillator? Some aspect or aspects of its physical behaviour?
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An oscillator is something that oscillates. Oscillation is a cyclic repetitive movement, ie; something that goes backward and forward and continually repeats.

Any circuit that produces a frequency has an output that is oscillating.

So if the circuit is simple it would be an "oscillator". I often make oscillators from 555 timer ICs or from logic gates or comparators. The fact that they may have digital levels in some part of the oscillation cycle does not exclude them from "oscillating".

Re multivibrators; an "astable multivibrator" is an oscillator but a "monostable multivibrator" is not.
 

t_n_k

Joined Mar 6, 2009
5,455
Any circuit that produces a frequency has an output that is oscillating.
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Re multivibrators; an "astable multivibrator" is an oscillator but a "monostable multivibrator" is not.
That makes sense to me. And I think the consensus is that an astable multivibrator qualifies as an oscillator.

It is possible however to view a single pulse (as produced say by a monostable multivibrator) as having a continuous frequency distribution (in the frequency domain) - according to Fourier.
 
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