THE 555 TIMER IC

An Interview with Hans Camenzind

 

Oral History – Hans Camenzind

Continued)

 

I went to the MIT library.  I had access to this library, and underneath the circular white dome, on the 6th and 7th floor, I spent almost a week looking through old issues of the Proceedings of the IRE  (Institute of Radio Engineers).   There was no index, no computer search, so I had to go through volume after volume.  I came across a concept called a phase locked loop.  I had never heard of it before. I looked at it and it was a very obscure concept, it was used to lock on to some faint signal. I think NASA used this to lock on to signals coming back from the moon for the lunar landing.

 

So, I took this concept with me, and after I left PR Mallory, I convinced Signetics to work on that.  Now, the phase locked loop has the advantage that it can capture a signal.  You have an oscillator that determines whereabouts it is, (it doesn’t have to be precise) – if the signal comes close, it will actually capture it.  It will lock on to it.  That was ideal, since I didn’t need precision.  I designed two or three circuits that became commercial, the first one was the 565, and then the 566.  And for that phase locked loop, I had to design an oscillator that was insensitive to the large variation of parameters inside the IC.  So you could set the frequency with a resistor and capacitor – that was it, and nothing else mattered.  That was done and commercially available when I left Signetics and became an independent consultant.

 

 

 

 

 

 

Oral History – Hans Camenzind

(Continued)

 

And I used that as the basis to design the 555 timer.  Here you have an oscillator, that is handy – the customer can choose a resistor and capacitor to determine the frequency.  And what I wanted to do was not to make just an oscillator, but a timer – trigger it, it would run for a certain time, then stop it.   The marketing manager bought the concept.  There was nothing like it at the time.  You had to use quite a few discrete components, a comparator, a zener diode or even two. It was not a simple circuit.

 

What made this go at Signetics was the marketing manager, Art Fury.  He was an unusual man in that he had practical experience. He had a lab at home, with components, and he would actually use a soldering iron and connect things together.   He worked at General Electric for a long and he knew the market – he had a gut feel for the market.  And he felt that a timer like that would sell.  No marketing data, no marketing research.  He was right, dead right.  It was a huge success.

 

 

 

Go To Camenzind Oral History,Page 6

 

 

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