[sdiy] SN76477 project / LF398 sample and hold ?'s

[John L Marshall]

Check the archive. There was a substantial thread a few months ago on
SN76477. A surplus store was selling the thin version at a good price.

John
----- Original Message -----
From: Derek Holzer <republikasleazka at hotmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, November 10, 2001 8:15 AM
Subject: [sdiy] SN76477 project / LF398 sample and hold ?'s


> howdy,
>
> just dropped into the list to see what's going on out there. i'm in the
> (long, drawn-out, oft-interrupted) process of building a a little
> synth-in-a-lunchbox based around an SN76477 chip, commonly used for such
> hi-brow applications as video games and pinball machines. too bad i
haven't
> got it all the way up yet... anybody else work with this IC that i can ask
a
> few details from?
>
> for the list, i've got a question:
> anyone have a simple schematic for a sample-and-hold circuit using an
LF398
> IC? seems like the simplest way is just to have a 0/1 logic input on a
> push-button to trigger it, an output and then the hold capacitor.
>
> then i looked at Rene Schmitz's YASH sample-and-hold circuit (
> http://www.uni-bonn.de/~uzs159/ ) and saw a pile of gates and an extra
> transistor leading into the logic input pin. what exactly is all that for
if
> all you really need to do is trigger it with a push-button switch? i'm
> curious...
>
> also: i'll be running +5 V into it, so how big should the hold cap be?
>
> thanks,
> derek
>
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