Comparator with open collector "precise " hysteresis

Sixty years ago I was building lots of tube stuff, mostly audio, Williamson and Ultralinear types. Had I realized how much the world would change I would have taken pictures. All I have remaining is...

Note the price ;-) ...Jim Thompson

Do you know the date of that manual?

It's still packed in a box from our last move, but more bookcases are on order and I will finally get everything unpacked, and I will post some of the innards.

However, my guess on the date would be around 1955-58, my last tube amp was built ~1958, I built my first solid-state amplifier (class-A, Delco door-knob germanium, 5W) in '57-58, and a real 30W amp as soon as I hit Motorola in 1962, with RF power transistors ;-) ...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Yup. I had an RC-26 floating around, somewhere (with an absolutely decayed binding), no idea where it went. ARRL handbooks, too.

They're all online these days; e.g.

Tim

I found this at a flea market:

Note the NEW TO-3 package!

One logic gate cost about 15x a steak dinner (at the Buck Forty Nine chain.)

I have several editions of ARRL... the oldest versions are the best... real detail for construction of circuits and antennas.

Good link, thanks! ...Jim Thompson

I really don't miss tubes. They were awful.

Some of the exotica, transmitting tubes and CRTs and PMTs, were pretty bits of glass.

They were pretty good up till the early 90s. My 1992 version is definitely better than my 1966 and 1976 editions. I haven't bought one since then.

Cheers

Phil Hobbs

I built my latest tube circuit in about 1993. I was doing an experiment in ionizing air with laser-produced plasmas, and built a little drift chamber that ran from about 1 Torr up to atmosphere (760 Torr). I needed to swing a grid from zero to about 750V and then let it go in a few tens of microseconds. By far the best candidate was an 811A, which worked great.

Eimac RF triodes are nice, and so are some of the stranger magic-eye tubes.

CRTs used to be amazing, before they had so many years of complete bilge presented on them. ;)

Cheers

Phil Hobbs

A tube isn't a tool, it's a component. I designed tons of electronics with tubes when I was a kid. The first professional design that I did, for money, was a radiation counter with Dekatron tubes. Dekatrons were interesting, a decade counter and a display in a single part.

What's to like about tubes? They are

Big

Hot power hogs

Fragile

Slow

Low Gm, terrible Gm/Cout ratio

Unreliable

Expensive

Tons of drift

Usually noisy

Microphonic

Not available in surface mount [1]

Design anything interesting with tubes lately?

Couldn't use a mosfet? I have a similar project going on right now, a multichannel 750 volt pulser for some optical PLZT things. I think I'll use mosfets!

Some of the big transmitting jugs were beautiful pieces of glass.

I like tubes as history and sometimes art, but they were mostly awful electrically, excepting exotica. I have a pretty nice collection, but to look at, not design with!

Well, I might consider a tube for a, say, 30 kilovolt amp.

The audiophools seem to like the very worst tubes, like 6SN7s and

--- Simplifying Google's: "a device or implement, especially one held in the hand, used to carry out a particular function." to: "a device used to carry out a particular function."

singles out components (which includes tubes) to be a subset of tools, since they're used to carry out a particular function.

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--- That doesn't mean you weren't a poor workman, it just means you managed to get the job done.

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--- You're preaching to the choir.

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--- So since you don't have a current need for tubes, they're the worst, but when they were all you had to work with they were the best?

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--- Nope.

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--- So what? That's just more of your neverending, irrelevant, self-promoting prattle.

John Fields

FETs couldn't get near the 811A's output capacitance, which iirc is about 5 pF.

Cheers

Phil Hobbs

On chip, I skip the switches and just swap input stages of the comparator by current diversion... screamingly fast. ...Jim Thompson

That is obviously true. People built computers from relays, when they were the best available technology.

Relays are still, at times, the best available switches; tubes seldom are.

An electronics discussion group would get dull if all people did was bicker and spew lame insults, and never discuss electronics.

Elaborating: The above is fine for two fixed references. For a fixed hysteresis about whatever reference the user wants, the current diversion trick still works, but you play sizing games with the two input diff pairs to create the hysteresis... likely what Microchip does. ...Jim Thompson