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DC signal to AC signal

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I respectfully beg to differ. This signal is a square wave which oscillates between 0v and +3.8v.
An AC signal - Alternating Current - oscillates from 0v to some positive voltage, back to 0v, to some negative voltage, then back to 0v. F'rinstance, U.S. line voltage cycles from 0v to +110v, to 0v, to -110v sixty times every second; 60Hz AC.

What I am working with is a DC voltage that is simply being turned on and off very quickly, hence "DC square wave".

The only difference is the reference point you're measuring from - it's an AC waveform. If all you need to do to alter it's DC reference, then feed it through a capacitor.
 
The only difference is the reference point you're measuring from - it's an AC waveform. If all you need to do to alter it's DC reference, then feed it through a capacitor.

that makes some sense, although - forgive the nitpicking - Alternating Current is defined as "periodically reversing direction". My signal always flows in a positive direction in reference to ground, and could be described as "intermittant DC".
Changing the 'reference point' sounds the same as converting from DC to AC. Also, I'm unclear why then feed it through a capacitor.

I appreciate your perspective.

- a -
 
It's more accurately described as a DC pulse. Current does indeed flow in only a single direction, technically making it a DC signal. The reason a capacitor blocks DC is, from the equation of current through a cap:

iC = CdV/dT. But for constant DC, dV/dT = 0, so no constant DC current flows through a cap. Further, you signal could be broken down to its AC and DC components:

VS = +/- 1.9V(AC) + 1.9V(DC). From the above equation, the current due to the second term is zero, thus the DC is blocked, and only the first term is passed.
 
My thanks to all for your insight and suggestions.

I thought I should put up a final result and say that Mike's suggestion worked perfectly. It even looks just like his drawing on my scope (that is looking at dual traces; each side of the circuit not colors, though ;-)

thanks again to everybody and I hope I can one day provide some input to someone in exchange.

- a -
 
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