16 Apr
2012
16 Apr
'12
2:15 p.m.
On 2012 Apr 16, at 1:09 PM, David Riley wrote:
On Apr 16, 2012, at 3:02 PM, Tony Duell wrote:
Well, yes. It is a figurative Swiss Army Knife of interesting bits.
It's kind of a shame that it's nearly universally referred to as a
555 *timer* when in fact it's really an interesting, connected
assembly of comparators, a BJT, a flip-flop and a resistor ladder.
I think the "timer" moniker keeps people from really employing their
wetware when designing things with it.
Back when it was new there was an incredible variety of circuits
using it, presented in datasheets, books, mags, and practice. It was
a bit of a popular craze to find a new use for the 555.
Indeed.
The 555 is a great solution to a great many things, and
It's amazing how many peole think it's useful for astable
(oscillator)
and monostable (timer) circuits only. I've used it as a bistable
and as a
schmitt trigger too.
The full 555 data sheet is something few people (not here, I
hope!) seem
to have read, they just use the standard 'cookbook' circuits. If
you read
and understnad the datasheet you can fidn any other ways to use it. You could even use it as a simple PLL core, though
I'm not sure how
much quality you'd get out of it.
The SWTPC CT-64 video terminal uses one in a PLL circuit to sync the
sync-gen to the 60Hz mains. It does involve 2 external FETs and
assorted RC though.