Simple pulse generator circuit

I seem to recall in some ancient gear I made many years ago, that they were insanely sensitive to EMI. A small ESD event completely across the room would trip the FF as if it were a full-swing logic pulse. I never did get that thing working reliably.

Jon

Pity about that. ON-Semiconductor don't make them any more, and don't seem to have any ECLinPS equivalent

I used them in the 1980's in the beam blanker for Cambridge Instruments voltage contrast electron microscope.

In fact I used several. One generated pulses wider than about 100nsec, range-switched by switching in a variety of timing capacitors, the other generated pulse in the 20nsec to 100nsec region, controller by adjusting the ramp generating current. For the narrowest pulses 5nsec,

- as a "start" pulse into into one side of a NOR-gate built with discrete broad-band transistors while the other copy, after routing through a series of small delays realised as loops of miniature coax, hit the other side of the gate as a "stop" pulse.

Very nice parts. It's a pity that they've gone obsolete.

-- Bill Sloman, Nijmegen

There was a DTL one-shot like that. I've never had problems with an HC123.

Well! If you want to get down and dirty. At the device level I've designed DLL's (delay-locked loops) for Silicon Graphics (Chippewa Falls, WI, the old Cray facility)... voltage controlled delays, in

Use C555 which has a 15ns raise/fall to drive this. R3 sets the pulse width..

Jamie

That's a nice design variant on the multi-inverter oscillator, but I don't see where it lends itself to easy adjustability from a front panel mounted pot- or the equivalent located at some distance from the high speed components. What the heck is wrong with a switched current source + capacitor ramp driving a high speed comparator, the other input of which is driven by a variable voltage threshold? The OP only wants a 25:1 pulse width adjustment so that's no big deal.

where it lends itself to easy adjustability from a front panel mounted pot- or the equivalent located at some distance from the high speed components.

In this case I didn't need adjustability. When I do, I generally do an adjustment of the inverter rails... easy monolithically, tricky in discrete's.

a high speed comparator, the other input of which is driven by a variable voltage threshold? The OP only wants a 25:1 pulse width adjustment so that's no big deal.

That works, but, down at 10ns that gets difficult at the discrete device level.

Larkin promised us a schematic with component values, but never has posted it.

You should adjust your wrap setting. I have mine set at 70 to allow room for attribution marks without spillover. ...Jim Thompson

It introduces a good deal more delay than is strictly necessary. We've already got the propagation delay from the initiating edge to the output of the first monostable, and you want to add in the same propagation delay for the second monostable? And a TTL monostable at that, so the delay depends on the state of the 5V rail.

Like everything else invented by John Larkin ...

Sure, I'm guilty of the unforgivable crime of not sharing your opinion of John Larkin's virtues as a circuit designer. At least you won't be tempted to report me to the FBI for harbouring dangerously anti- American attitudes, as Jim Thompson says he did. There's no committee

- as yet - for investigating people who aren't sufficiently credulous about John Larkin's self-advertising.

-- Bill Sloman, Nijmegen

Of course you aren't dangerous. You aren't effective enough.

He's using Google Groups.

Google Groups has no editor setting capabilities ?? ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Don't tempt me. I only use my powers for good, but you do work for the dark side from time to time, and not only by propagating climate change denialist propaganda.

-- Bill Sloman, Nijmegen

Dark side? I refused to sell to tobacco companies. I refused to help a certain middle-eastern country develop nuclear weapons. I've given away far more than I've earned.

You don't use your powers for good; you aren't effective enough.

So, do you admit that the dual one-shot thing has a race hazard? If so, what's "too crude and extravagant" about my suggested fix? What do you have that's better?

see where it lends itself to easy adjustability from a front panel mounted pot- or the equivalent located at some distance from the high speed components.

driving a high speed comparator, the other input of which is driven by a variable voltage threshold? The OP only wants a 25:1 pulse width adjustment so that's no big deal.

OP: That's a nice design variant on the multi-inverter oscillator, but I don't see where it lends itself to easy adjustability from a front panel mounted pot- or the equivalent located at some distance from the high speed components. What the heck is wrong with a switched current source + capacitor ramp driving a high speed comparator, the other input of which is driven by a variable voltage threshold? The OP only wants a 25:1 pulse width adjustment so that's no big deal. END OP

Did that wrap right?

Haha-

Who knows? They keep changing the @#$%^&*(#@$%^&*@#!$%^& thing, and calling it 'the new Google Groups' after every change.

nal

rk

So where did you steal the unearned money that you have given away? You've made it fairly clear that you didn't have an inherited fortune to give away.

Not where you can see the effects.

Obviously - the propagation delay from the trigger to the start of the output pulse can be anywhere from 20nsec to 70nsec for either monostable, and you've got to mask that first 70nsec in consequence

Anything with a shorter propagation delay; my preference was for a short trigger pulse which could be used to mask the final output pulse until both monostables could be relied on to have fired. I'm not going to design the whole circuit just to prove the point - as far as I'm concerned the two monostable solution is cheap and nasty, and I wouldn't put in any effort on it until I was convinced that iCod didn't need anything better

They must have been desperately scraping the bottom of the barrel.

They wanted me to train their people in high-speed electronics design. Good pay, travel, gratitude were offered.