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.

 

How about a small microcontroller with say an 8MHz. Crystal Oscillator. Programming should be a piece of cake.

 

You can use analog devices Timerblox series of chips as well.

It could be done with a 555 and a monostable such as https://www.ti.com/product/CD4098B

Look at this list https://en.wikipedia.org/wiki/List_of_4000-series_integrated_circuits (search for monostable) The CD4538 is probably better.

 

The turn on time is not so important, but more precision is better.

So which should be more accurate, the 1µs or the 1s?

 

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?

 

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?

 

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

 

555 pollution

Funny.

Another way to skin a cat. Use a Dallas chip for the 1pps interrupt and a monostable, you might just need a processor to set things up. Not necessarily advocating this solution.

 

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

 

What does the 1 pps do?

The answer might trigger some new ideas.