> The 555 is dedicated as a timing device.
When you work with it for any amount of time you come to
realize the design and layout is very practical and the chip
is now considered an industry work-horse. But it can be
used in linear applications... so never say never.
> The LM324 is a quad op-amp and one of the poor ones. About
> the only advantage is 4 in one package.
When is good enough, good enough?
Internally frequency compensated for unity gain
Large DC voltage gain 100 dB
Wide bandwidth (unity gain) 1 MHz (temperature compensated)
Wide power supply range: Single supply 3V to 32V or dual
supplies ±1.5V to ±16V
Very low supply current drain (700 µA)-essentially
independent of supply voltage
Low input biasing current 45 nA (temperature compensated)
Low input offset voltage 2 mV and offset current: 5 nA
Input common-mode voltage range includes ground
Differential input voltage range equal to the power
supply voltage
Large output voltage swing 0V to V+ - 1.5V
Another well known industry work-horse chip. Sometimes you might
not want a high performance chip in the drivers seat. There are
many cases where higher spec parts can work "to well".
> As for use as a timer the 324 needs lots of glue to make it
> work. Not saying don't use it, but for a timing device the
> 555 is made for this with lots of flexibility.
Sure the 555 is an industry standard timer chip, but an op
amp section can easily be made into a timer function without
much work. The Hamtronics COR-3 circuit is a perfect example
of where one chip does both functions very well.
> If you want a op-amp I prefer the LF353 for audio and the
> LM358 has the rail-to-rail service and is better than a 324.
If one wants to get nit picky over chips... I've got page lists
of better audio chip data sheets. But the 324 is more than
good enough for many tasks. A big plus is the cost per package
makes it a great dollar value.
I once had to rework a simple op-amp design using the LM-3900
Norton chip because it was the only animal that didn't immediately
go crazy at the mega watt rf-environment location. Sometimes dumb,
stupid and lower performance chips are the more practical or
cost effective answer. However, cost per pacakge most often
seems to be the person in the drivers seat making really large
quantity chip purchases.
cheers,
s.
