Zeners in Series

Nov 09, 2019 80 Replies

It's part of an OEM laser controller. About half of our business is custom OEM stuff. A lot of the visible products are losers, don't sell, but they work as advertising, show capability, and are fodder for press releases, which make links.

We did have the customer logo on our site

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but they saw it and made us take it down.

Since you don't know who they are, allow me to say that they are real jerks.

John Larkin Highland Technology, Inc lunatic fringe electronics

If a jerk purchases 3500 pieces, presumably at a reasonable profit, that's not so bad. You can suppress your feelings all the way to the bank.

Thanks, - Win

That is some small consolation.

What's tragic is how many billions of dollars they make.

John Larkin Highland Technology, Inc lunatic fringe electronics

What does "roughly zero" mean? Is it zero or +/- SomethingLarge?

We've got a few back that were mechanically mangled. There was a burst of failures from one site caused by some outrageous ground loops that incinerated some line drivers.

It's basically a 250 MHz, 12 bit ADC that integrates light pulse energy and can acquire waveforms.

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That switching power supply is an inch or so away from the ADC, and noise is under 1 lsb RMS.

John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com

Measuring Switching Regulator Noise

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Other Jim Williams Videos
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Watch the wrap.

Yes but the way the secondary feeds back to both sides of the other transformer, it looks like the purpose is to double the voltage. I've never seen it done that way.

tripple, you could draw it as one primary and three secondaries

What's the ISDN transformer's p/n? It's nice and small, right? Will any old one work?

Thanks, - Win

The ISDN transformer windings are 1:1:2:2, so it's connected as 1:5. The connection is the way it worked on the PCB layout.

I assume that ISDN is dead, but the transformers are still available.

John Larkin Highland Technology, Inc lunatic fringe electronics

This one is 1:1:2:2, being used as 5:1.

TALEMA SMJ-140B

which can be hard to get,

or

MINNTRONIX 4809184R

John Larkin Highland Technology, Inc lunatic fringe electronics

I guess that would be zero + a few. Whatever a few is. Certainly not zero.

If a customer physically or electrically abuses a unit and breaks it, we don't consider that to be a failure. Neither does the customer.

This customer is very serious about quality, and tracks failures and issues vendor scores. A failure here could cost megabucks. So we dispute "failures" that were field damage.

John Larkin Highland Technology, Inc lunatic fringe electronics

What do you think about the Bel 2798D 16 Pin SMD ISDN Transformer? I have about 2500 of them, in storage. I need to build some clean 90-100VDC power supplies for old battery powered tube portable radios.

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How much power do you need?

I guess a battery powered radio doesn't need much B+.

You'd need to run the frequency up to avoid saturation, so there could be an EMI issue. Maybe use a doubler or C-W multiplier to allow keeping the frequency down.

John Larkin Highland Technology, Inc lunatic fringe electronics

What is so difficult about using a ferrite E core and just 2 x 12 turns? For a bit of battery based tube radio of the old days, say a DL92 output stage, you need about 100 mA, plus the rest of the tubes say 200 mA at 90 V.

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You also need 1.4 V for the heaters (down convert). Even a 1 transistor blocking oscillator or 1 transistor driven by a 555 timer would work. then a 1:2 turns ratio can give you 140V or so from 12V in. One extra turn for the heater,,, Use about 1 turn per volt. Or 2 transistors with voltage stabilizing feedback, repaired just such a thing a week or so ago. For things like one-off just keep some small ferrite E cores and some wire in stock. Yes frequency should be above audio ;-), say 15 kHz or higher.

He doesn't have 2500 of them!

John Larkin Highland Technology, Inc lunatic fringe electronics

He does not have 2500 radios either! Why compromise?

IIRC, our Production gives a rule-of-thumb estimate of $0.27 to take a part reel out of the stockroom and put it on a feeder (to load the first part). That's an estimate per board, so some assumptions not given here are obviously embedded in that estimate.

And the cost can, in some cases, be multiplied by 2 for a two-sided board.

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