Re: [CAD_CAM_EDM_DRO] Mostly on topic or at least getting there

You can do it with a pare of CMOS Analog Switches, (4016 or 4066), driven by a
D flip-flop in divide by two mode. Conversely, you can get 8 traces by using a
4051, or 16 traces with a 4067 type Analog switch. I recomend 8 traces max, as
16 will make your eyes grow fur. Just too little differentiation between the
traces. Basically, you hook up the scope probe to the, "pole pin", and use the
other 8 to switch between the traces through an R2R network. The 2R's are
hooked up between each of the 8 pins to provide a level shift, and hook up your
8 probes to the R's. A pot at the top and bottom of the R2R chain will supply
a bit of vertical adjust.

Tune your scope to see the signal you want to see, and then adjust the
Oscillator driving the circuit, such that it will show the top or bottom of it's
square wave from one side of the scope to the other. Drive a divide by 16 chip
with it and use the first 3 outputs to drive the 4051. You just built an 8
trace scope circuit.

It all looks like you're seeing it all at the same time, but you're really time
shifting between the 8 probes, each one taking it's own little bit of time. You
can get fancier with it, like providing a signal to activate something in the
middle of trace N, but that's about all there is to it.

Bill

On Mon Nov 19 15:15:51 2001, Ian Wright, <Ian@...> wrote:

>This post reminded me of something I am trying to sort out. I have a basic
>single-trace scope and I have been looking for a circuit for a trace
>doubler. These used to be around when I was a lad and my scope then used a
>3KV anode tube out of a WWII radar set but I don't seem to be able to find
>one now - any ideas?
>(for those who don't know what I'm talking about, the circuit I'm seeking
>samples two signals alternately at a high frequency, applies a voltage shift
>to each signal and displays the result on a normal single trace scope as
>though it was a dual trace one. - good enough for applications where the
>signal frequency isn't too large like looking at the outputs from an
>encoder)
>
>Ian
>--
>Ian W. Wright
>Sheffield UK
>www.iw63.freeserve.co.uk

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