ECL: Why'd they use negative voltages?

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Cool stuff. ...and easy to use.

If you have the old MECL databooks treasure them, don't let them end up in the recycling. Both Motorola and Fairchild did a most excellent job explaining stuff in there and I assume many of the authors are no longer with us on earth.

If you do a good job bypassing the supply and keeping leads short there isn't much that can go wrong. Except for one thing: Some series have only half the logic swing and that almost bit me once.

Got a schematic?

No. Insane.

Yikes! I used to push 600W when I was in school but never actually *listened* at that level! :>

OTOH, I recall a friend designing a 2KV, 2KW supply (at the same time I was working on the aforementioned CPU). He used to joke that he installed switching transistors to protect the *fuses* from blowing (it would vaporize the emitter? pin on the TO-3's). Boss was not amused (I guess they were some pretty expensive switches :> )

I prefer things that don't *bite* when you touch them!

-1.4, IIRC (but maybe not, since it's been almost 25 years since I used MECK

I worked on a test system that had a 100A -4V *linear* HP supply in it. The thing was the size of a small refrigerator. The other engineer did the 1600 pin pin-driver logic in proprietary ECL (-4V). I did the clock drivers in MECL 10K. I only needed about 50A for the 64 clocks. ;-)

But it can snap, and it usually does so on a Saturday night in the boonies. About 30 miles past the sign that read "No services next 60 miles". Sez Murphy :-)

The one on the Citroen never gave me trouble in all those six years, until the bottom rusted out from underneath the car. Then the whole engine including generator was sold to Norway.

Dunno. This was 35 years ago. At the time, I didn't realize it wasn't "normal practice" :>

The Vbb supply was a *shunt* regulator. A bunch of Lambda power supplies driving a pair of *big* diodes "selected at test". A colossal waste of power.

This was the brains of a "600-pin tester". Programmable power supplies to the UUT. Programmable thresholds for the input comparators. 1ns timing resolution. It was just "insane".

Man, that even dwarfs the tube amp I build in school. It could push north of a kilowatt but not that high. Mostly because that's when the circuit breaker popped ...

We did listen. Until a car with a blue hump on top and a guy in uniform inside showed up.

Oh, alright -- I suppose the likelihood of enough teeth breaking off the generator's drive gear so as to completely disable it is pretty much nil...

Do you currently carry about one of those "emergency" replacement belts... just in case? (E.g.,

I've never had a belt fail in my entire life, although I have had a radiator hose spring a leak while in the road... and then on another car the (plastic) radiator itself crack...

---Joel

We would have fun "broadcasting" bursts of 2600Hz :>

That's NOT original-crispy ECL :-) ...Jim Thompson

that's

People used to publish schematics of their chips, or at least functional schematics. No more.

The EPs are SiGe, I think.

John

They're very forgiving about bypassing too. That's one of the big advantages of ECL. Current is higher, but switching current is far lower than TTL, for instance.

Another gotcha: some parts really don't like having their inputs pulled all the way up to Vcc. So you have to make a logic "1", a junction drop down maybe, and pipe that all over the place.

John

Yep, all that and 1600 pins. ;-) OTOH, it was a DC logic tester (clocks ran at system speed - 25ns).

Just be careful when doing wired-OR. It seems like a natural in ECL, until you start to think about the speed of light.

John

It didn't have any gears, it sat right on the drift shaft, behind the the fan (also on that shaft). The points were also right there and those did require the occasional TLC. The outside of the fan had the receptacle for the crank which I frequently used because the price of a

Cool. Not sure it they'd work on my car though, it has a pretty wide belt.

I had belts snap on me. And the occasional alternator fall out of the car. Chrysler screwed up the mount by using an aluminum strut. After making my own from steel that never happened again.