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Old 23 March 2014, 11:43   #260
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Originally Posted by robinsonb5 View Post
Well I've drawn up a rough schematic, since it's the easiest way of explaining what I've actually done - but there may be a better way of doing it, and the resistor values could probably do with adjusting.

I'm using the "step" pulse from the floppy interface to make the sound, and the rest is simply to trigger the piezo sounder. (Note that the Gotek pulls the Step pin up to 3v3, not the usual 5v.)

I sometimes get some unwanted oscillation which makes the sounder squeal, but it goes away when I touch the sounder, so I guess C1 probably needs to be bigger?

The circuit was developed largely by trial and error, and there may be a better way of doing it. The main transistor (T2) needs to be a very fast switching type, since the Step pulse is active low and very short. It also loads down the step signal somewhat, so may need a resistor between the emitter and ground?

I'm not sure the 2N2222's even necessary, though its comparatively large storage time should be widening the step pulse somewhat.
Awesome! I had to look up what a piezo sounder was. I have found a few on eBay but not sure if these would do.
Would something like this be correct?
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