old test gear

Digital scopes seem to do as much as they can in software. That has some serious limits.

Trick: if you want low jitter, don't use the scope external trigger connector: trigger off a vertical channel. Most digital scopes quantize the external trigger to one sample clock, but play tricks with channel triggers.

Interesting. I wonder which of mine are like that. The 1180x ones are external trigger only. (I have an SD-51 trigger head, which I've never used except to test it out--it seems to be some tunnel-diode thing that improves triggering off gigahertz input signals.

Cheers

Phil Hobbs

The 1180x sampling scopes are fine. It's modern "digital" scopes that generally don't interpolate the external trigger. Some do, like our $50K LeCroy. Vertical channels bandlimit and digitize, so Mr Shannon helps.

It's easy to try.

Use the Elevator, preferably on its cart. But of course it was worth it to have one on hand.

And replace the rectifier with silicon diodes.

Bill

The rectifier replacement may create a surprise. My late friend got an old Telequipment scope with very dim picture, and he changed the rectifier tube (valve for Brits) to a silicon diode. The old capacitors in the scope had already got used to the lower voltage, and they started a sound pffftt... He pulled the plug, but a little late, and the room got filled with aluminum confetti.

Uh, VGA output to a projector. I'm pretty sure that is doable with many scopes. I know a lot of Tek scopes contain a PC running Windows, so I'd be surprised if they don't provide a VGA or even HDMI output.

Rick C.

And anyone can build a radio, all you need is to plug these 6 modules together. But when it's all in one & ready to work the upsides are obvious.

Whether that particular product is useful is another matter :)

NT

For sure, some of the time. And sometimes the modern tools can do things not practical once.

FWIW I once diagnosed & repaired some TVs using just 3 lightbulbs as the testgear. They acted as voltmeters, ammeters, droppers & current limiters.

NT

What's the best way to get the biggest *bang* out of an electro? I've never seen one go and consequently feel there's something missing in my life.

The most impressive confetti generators IME are the old chassis-mount alumi num can ones. I do _not_ recommend putting one of those across the mains, b ecause you could be injured by the resulting steam explosion, hit by shrapn el, get electrocuted, or burn your house down. So don't do that.

Cheers

Phil Hobbs

Unless they declare bankruptcy before that.

If you have Tek 2465 keep those as well. Best scope ever made on this planet. They can truly save the day with nasty analog problems. DSOs only go so far no matter how fancy a persistence mode they have.

It's similar with old HP3585 baseband spectrum analyzers which can still run circles around newfangled ones.

Is there a pub like Zeitgeist near the new place?

r)

see

the

ey

all

here were meters like that, using a focussed lightbulb IIRC.

ctor.

ether. But when it's all in one & ready to work the upsides are obvious.

Actually, just the opposite. I would find it hard to imagine a mechanical configuration that would allow a scope to be usefully placed on a workbench or table while projecting an image on a wall. But that is as much a probl em with the use case in general, having the projector built into the scope just makes it worse. Most likely the projector should be mounted somewhere high and behind you, a bad place for a scope body, so an external projecto r is the right way to go.

Rick C.

There were meters like that, using a focussed lightbulb IIRC.

jector.

ogether. But when it's all in one & ready to work the upsides are obvious.

l configuration that would allow a scope to be usefully placed on a workben ch or table while projecting an image on a wall. But that is as much a pro blem with the use case in general, having the projector built into the scop e just makes it worse. Most likely the projector should be mounted somewhe re high and behind you, a bad place for a scope body, so an external projec tor is the right way to go.

I can't see much use for a projecting scope as product. But fwiw if one did want a projecting scope, a built in display would be far cheaper, smaller & lighter than a full featured external projector as the required features are far more basic. It would also be more convenient. A control would be re quired to adjust for the angle of the wall relative to the projector - not at all difficult.

NT

The originals (around 1959) had selenium rectifiers.

Bill

I suspect that I'll never use an analog scope again. Haven't in years.

There are several classic dive bars, but nothing quite like the ambience of Zeitgeist [1]. Trick Dog has an astonishing burger and world-class fries.

Now you've said that, I am *totally* going to do it! :-D

This all sounds very familiar - from like 20+ years ago. This is the joint you were supposed to be taking *me* over that wager, right?

That on had a tube, less stink risk. It was from late 1960's or early 1970's.

r)

see

ey

It was noted at the time (1960s/70s) that you had to put a series resistor with the silicon diodes as they were more efficient and the DC voltage could rise as much as 25% over the Selenium output pushing the caps past their maximum rated working voltage.

If you ever replace silicon rectifiers you also need to fuse their AC input side to protect the transformer against shorts. Selenium rectifiers failed open, whereas silicon fails shorted...

John :-#)#