Break Points
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wswbln
Wow - reading all this "hype" :-) about the 555 I feel really exotic since in ...
Simpleton
My first academic project (actually a mini-project) was around IC555. It got me ...
555 Contest
Jack Ganssle
1/24/2011 12:03 PM EST
Win valuable prizes in a 555 timer contest!
In about 1970 Hans Camenzind designed the 555 timer, which was brought to market by Signetics, a company that was once a powerhouse in this industry. Signetics brought out the 2650 eight-bit micro in the 70s, which was pretty influential at the time. Their quirky 8X300 processor never got much market share, but we used it in combination with AMD’s bit-slice 2900 parts to build a graphics processor for an instrument.The 555 timer, and its variants, are made by around 20 companies today, forty years later, and something like a billion are sold every year. That’s a lot of parts.
This timer is as iconic as the 741 op amp, though the latter has been largely supplanted by more modern single-supply devices. Those of us in the digital world routinely expect ICs to sport hundreds of thousands or millions of transistors, but the 555 manages to offer an astounding array of functionality with just about 20.
A friend used to ask “Is there anything the 555 can’t do?” This is a part that can be monostable, astable or bistable. I keep a copy of Forrest Mims’ slender but awesome Engineer’s Mini-Notebook for the 555 stuffed in with my much more massive The Art of Electronics. Mims’ book was marketed by Radio Shack and still has a $1.99 label on it. In those yellowing pages he shows how to use the 555 in 28 completely different applications, ranging from a key debouncer to an IR security alarm to a DC to DC converter.
For a good tutorial about this timer check out the one at Sentex on line.
Turns out Chris Gammell of The Amp Hour and Jeri Ellsworth, whom I have mentioned here before, are sponsoring a design contest. Create a project using one or hundreds of 555s and submit it on line. Their motto: You’ve got 8 pins… and one shot!
They are still angling for donated prizes, and could use some volunteer and perhaps industry support, but this sounds like a lot of fun. Winners will, at the very least, have some great resume fodder. (When hiring I always give points to those whose avocations intersect their vocations).
But act fast – the contest closes March 1. And have fun!
Jack G. Ganssle is a lecturer and consultant on embedded development issues. He conducts seminars on embedded systems and helps companies with their embedded challenges. Contact him at jack@ganssle.com. His website is www.ganssle.com.
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ChrisGammell
1/24/2011 12:24 PM EST
Oh and Forrest has agreed to judge the contest for us! Forgot to tell you that Jack. Thanks!
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clay_cowgill
1/27/2011 11:22 PM EST
Hans Camenzind is onboard as a judge now too. :-)
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JackGanssle
1/25/2011 8:37 AM EST
I just learned that the 8X300 was used in more than 30% of fixed disk controllers for a while. So it did have some decent market share. Thanks for the correction, Eric.
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Datamstr
1/25/2011 9:45 AM EST
Back in the 80's I worked at Westinghouse Numa-Logic and we used the 8X300 in the design of a Programmable Logic Controller.
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pmoyle
1/27/2011 2:10 PM EST
As I recall the 8x300 was used in the Modicon 484.
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cdhmanning
1/25/2011 7:12 PM EST
Remember the days when a 555 was obligatory!
I have a pulse induction metal detector that uses 6x 555s.
Four are used to run a timing chain: main clock, coil pulse width timing, delay, sample window timing.
One is used as a voltage to frequency converter to convert a voltage to audible clicks for the headphones.
One is used as the oscillator for the charge pump voltage converter.
The original design called for 7555 (CMOS version) but I found these to be too sensitive to static. I fitted regular 555s and have had no problems.
A newer version of the metal detector uses a single 8-pin AVR for all the timing and voltage to frequency conversion which reduced board real estate by 75%.
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johnmoran
1/27/2011 4:03 PM EST
Hello cdhmanning
A copy of the circuit of the original metal detector would be very useful.
Kind regards - john
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Ron_Aronowitz
1/27/2011 2:39 PM EST
I feel a little emotionally attached to the 555 Timer. I first used it about 33 years ago to design my first real electronic circuit, a music synthesizer that would play 16 user adjustable tones. The 555 timer was used as the clock source to sequence through the 16 tones and as the tone generators, using trim pots to adjust the rate of sequencing and the frequencies of each note. I miss those days.
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DJAus
1/27/2011 7:08 PM EST
Didn't realise that the 555 was still in vogue! Would have thought that it was replaced by a digital simulation of it.
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Simpleton
1/28/2011 4:06 AM EST
My first academic project (actually a mini-project) was around IC555. It got me the first prize for simple application I had developed - Automatic porch light controller. After so many years I still find space for this IC in few projects atleast at PoC level. I agree that after OpAmp this is another versatile chip.
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wswbln
2/7/2011 4:51 AM EST
Wow - reading all this "hype" :-) about the 555 I feel really exotic since in 35+ years of designing (analog and digital) electronics I used on the whole maybe about 5-10 of them...
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