Pulse generator design

Thread Starter

WilliamN

Joined May 3, 2021
3
Hello, I'm looking to make a one microsecond wide pulse every one second. My only experience is working with an LM555, but I believe it can't go that low. If I can get any advice or pointed to the right direction it will be appreciated. There is no trigger so it has to be self sustaining, so maybe a crystal oscillator or something similar would be necessary. The turn on time is not so important, but more precision is better.
 

Thread Starter

WilliamN

Joined May 3, 2021
3
1s should be more accurate, I'm thinking of using a microcontroller with the internal timer hardware and use a timer and comparators to turn an IO pin high and low. I think a crystal driving the microcontroller should provide good enough precision for the 1pps. What's you're option on this?
 

Thread Starter

WilliamN

Joined May 3, 2021
3
How about a small microcontroller with say an 8MHz. Crystal Oscillator. Programming should be a piece of cake.
I think I should use a timer and comparators to turn an IO pin high and low. Also like you're saying using a crystal to drive the microcontroller should be good enough. Any other recommendations?
 

AnalogKid

Joined Aug 1, 2013
9,362
Crystal-controlled 1 s, adjustable 1 us:

U1 - CD4060 14 bit counter with a 4.194... MHz crystal >
U2 - CD4040 12-bit counter >
U3 - 555 1 us monostable

More pins than a PIC, but no typing.

OR - For a more environmentally-friendly design that reduces world-wide 555 pollution -- Replace U3 with a CD4081 quad AND gate: one gate selects a 0.954 us pulse from U1 and U2, and one gate resets the counters after that pulse. "No adjustments; can not drift." That leaves two spare AND gates for other stuff.

ak
 
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AnalogKid

Joined Aug 1, 2013
9,362
Back in the days of quadraplex video recorders, the retrofit Allen signal system used a 15' coil of coax cable, shorted on one end, in a module as the delay element in a monostable circuit for a pulse-counting FM demodulator. Years later, AMPEX used the same trick, combined with MECL logic, in the AVR-3.

Not necessarily advocating this solution.

ak
 
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