Re: fast discrete PHEMT one-shot

John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:

On Wed, 15 May 2024 22:46:27 -0000 (UTC), piglet
<erichpwagner@hotmail.com> wrote:
 

John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:

 
https://www.dropbox.com/scl/fi/agatzclr8pvr5470g6mc4/Phemt_One_Shot_1.jpg?rlkey=cwnx0qd7ajgnh8otf627x5lku&raw=1
 
Regular monostables are terribly slow. This one has low prop delay and
high rep-rate, if the sim is to be believed.
 
SAV541 is mostly specified as an RF part, but it's a dynamite switch.
 
I can post a link to the files if anybody wants to play with this. All
my values are first guesses, no math involved, and it works!
 
My SAV541 Spice model is a revision of Phil Hobbs' original.
Mini-Circuits is adamant that they will never provide Spice models, a
typical RF-bigot attitude.
 
 

 
Yay! Eccles-Jordan ride again.

 
1918!
 
I think that was a bistable. I don't know when the monostable was
invented.
 
People tend to roll eyes when I use one-shots in logic designs. I
can't see why.
 
>

Probably because the classical TTL and CMOS multivibrator chips are so
horrible.

The CMOS versions of the 555 are about the best, which is amusing since
they’re the ones that get all the abuse.

My usual rule is that one-shots are fine if you can accommodate a factor of
3 uncertainty in the delay.

Joerg used to wrap feedback loops around them.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics