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Re: 555 timer



Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

Jonathon

The 555 timer is a "universal" mixed signal timer IC that has been used for
everything from PWM control of motors, to missing pulse detectors,
to 1 bit A/D converters, to power supply controllers, to F/V converters
(tachometers), to astable oscillators, to monostable timers to VTTC
staccato controllers, HEI systems, to....

The chip has been around from 25 years+, and is still one of the most
flexible commercially available chips.  You can just about bet that there
is at least one or two of them in your house in consumer electronics.
Radio Shack sells them, as just about any other electronics mail order
house (MCM, Digikey, Jamesco, etc.).  I have seen them as cheap as
20/$1.00 at hamfests.

There are the single timer 555 chip, a dual 556 chip, and a quad timer
(with reduced functions) 558.  They are available in bipolar as well as
CMOS versions.  Bipolars can sink and source up to 200mA (I don't push
them above 100mA), and as oscillators can be pushed to 200-250Khz.
CMOS units can clock well in excess of 1MHz, but are limited in the
available sink currents.  Notice that CMOS devices can only sink current.
Packages can usually DIP (leaded), and surface mount (SMD) are available.

I recommend you get a book on the chip, or study some of the websites
concerning applications of the chip, there has been literally 1000's of
applications for this chip over the years.  One of the best user references
for the 555 timer is:

The 555 Timer Applications Sourcebook with Experiments
Techniques, Applications, and Experiments Using the 555 IC Timer
Howard Berlin, Edgewood Arsenal; College of Engineering/Univ. of Delaware,
4th printing 1978; Published by E&L Instruments

Maybe available in later printings, an absolutely awesome book in "plan speak"
with simple algebra, and literally hundreds of applications and experiments for
hobbyists.  HIGHLY RECOMMENDED.

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA


Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Kidd6488-at-aol-dot-com>
>
> Ok, I've heard a lot about these things, and they seem like an interesting
> tool. I want to know more about them. First of all, where can I get one, and
> how much do they cost? Second of all, how do they work, and how do you hook
> them up? They have 8 pins, correct? or are only 8 used. Is it capacitance or
> resistance the determines the timing? I hope to use these to have an
automatic
> duty cycle.
>
> ---------------------------------------
> Jonathon Reinhart
> hot-streamer-dot-com/jonathon
>
> PS, anyone reply to my question about 4.5" or 6"  being the best for a
> 12/60....