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push-push on/off switch

Nobody? Now hold on there John. If you'll look back in the posts you'll see I mentioned measuring power MOSFETs holding their gate voltages for days and even weeks. Actually, I've spent a little time exploring the MOSFET open-gate scene. Some of what I learned I posted here on s.e.d. in the past.

For example, I wanted to see exactly what the leakage rate was, so I biased a MOSFET on at about 1mA, and disconnected the gate. Then by logging small changes in drain current I could indirectly observe small changes in the gate voltage (after measuring the FET's transconductance at that current). In general the leakage currents I observed were VERY low.

In one experiment the gate voltage was about a volt higher than the drain voltage, yet after hours of rock-solid stability the current stepped up a notch, indicating an increase in gate voltage! This could not have been due to leakage, because that would have meant a decrease in gate voltage. Maybe a cosmic ray impact?

Anyway, interesting stuff, and worth revisiting.

Reply to
Winfield Hill
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What I meant is that nobody seemed to have tried the push-push R-C-switch thing, but that didn't stop a few people from claiming it wouldn't work, which I said, or that it wasn't practical, which I didn't. Whack-a-mole again.

Phil Hobbs is the only person who obviously understands the circuit dynamics. JF and JT didn't, and maybe still don't, so tried to give me a hard time about it.

Yup.

Another issue to revisit:

Suppose we have a super-low bias current opamp connected as an integrator, with a small feedback cap, say 0.1 pF, and no input. Short the cap briefly, release, and digitize the output. Each electron of leakage will change the output voltage about 2 microvolts. Is there any statistical analysis that can be done to the data to demonstrate the quantization of the leakage, to dig the individual electron steps out of the noise?

Next question: if we move a small charged object in the vicinity of the summing point, we can change the voltage at the output node by any desired small amount, far less than 2 uV. Is that quantized to single-electron steps? I don't exactly see how a capacitively-induced signal will be quantized, but then any charge must be quantized, so I'm confused.

John

Reply to
John Larkin
[snip]

Neeerp! I understood it immediately and saw the POOR ENGINEERING PRACTICE and said so. It fails even the most cursory reliability checks.

Cutesy doesn't hack it, no matter how much fun you had with it.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

And you danced all around evading my question about putting it into your products... like a cornered liberal ;-)

Shame on you, John.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

Gosh, then who said "Nonsense, you're at equilibrium." ?

PEP seems universally to mean "I don't like it."

By what standards? What parts will fail?

What does "hack" mean? Sounds like "I don't like it" again.

I originally did this as a quick way to bias the fet into partial conduction, as a way to estimate gate leakage current. The RC flip-flop thing was just a neat by-product. Sorry you don't approve.

John

Reply to
John Larkin

I told you it isn't in any of my products. When we handle pushbuttons, it's with a microprocessor.

Oh, I'm just mortified.

John

Reply to
John Larkin

Sno-o-o-o-ort! I bet you are ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

Jim Thompson snipped-for-privacy@My-Web-Site.com posted to sci.electronics.design:

I don't think you want to go to far west on I10 or I8; look at this:

formatting link

Reply to
JosephKK

Yep, a 35 mile section of I8 in California is closed, but it's extraordinarily rare for I10 to get more than just a little smoky.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

formatting link

On this map, there is no fire in Mexico. The border crossing is closed.

So send every one to Mexico for a vacation.

don

Reply to
donald

JT didn't like this one that I posted in July, either:

9-12V Vcc ---[1K]---+------+ | | | \\e [330uF] |--- 2N2222 | /c | | | [LED] | | | [1K] | | Gnd ----------+-------+

Base - no connection, Vcc somwehere between 9-12 volts. Damn thing blinks.

Ed

Reply to
ehsjr

Interesting question. Let's assume a perfect, zero-leakage op amp connected as an integrator with a zero-leakage cap. The total charge in the summing junction won't change, but the electrons will fluctuate within all the metal making up the summing junction, constantly changing the charge on the integrator cap. This will show up as noise on the output.

Now you approach a positively charged object to the summing point. This will make the elctrons a bit more likely to stay near that object and off the capacitor plate. So the time-averaged number of electrons on the cap plate will be a bit lower. But the time-averaged charge is of course not quantized, so what you actually get is some sort of noise-PWM.

robert

Reply to
Robert Latest

So what's your point? Someone pulls a few parts out of the junk box and plays with them. It has nothing to do with engineering practice. It's not even engineering but playing. You never did that? Poor you.

robert

Reply to
Robert Latest

In principle, yes you can. People make single-electron transistors, where the quantization is pretty obvious. It's very hard to do at room temperature, though, just because kT is so big compared with the energy of one electron on any reasonable capacitor...

E = 0.5* Q**2/C

so if you want one electron to be detectable with a SNR of 1.0, you need

kT C C

I agree with Robert L--the capacitors aren't isolated enough to get charge steps in this situation.

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

"Not Good Engineering Practice."

John

Reply to
John Larkin

[snip]

John, For partial redemption, please _explain_ to the mob HOW/WHY this blinker works ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

I don't know, but I've seen it referred to on lots of web sites, so I assume it does. Looks like a negative-resistance avalanche breakdown or some such. Hell, you're the bipolar semiconductor expert, so you should explain it to us.

Are you sure it doesn't work? Before you make that flat assertion, maybe you should try it.

I have often wondered: if an emitter is grounded and there's positive voltage on the collector, and you then pull the base negative, to zener the b-e junction, you're clearly tossing a lot of carriers into the junction. So what happens to collector current?

John

Reply to
John Larkin

I didn't say it didn't work, I said it wasn't reliable.

FIVE years ago I posted....

formatting link

So I DO know why it "works".

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave
Reply to
Jim Thompson

But it's fun, as is your mosfet push-push. :-)

Ed

Reply to
ehsjr

What, "loser"? He posted a cute circuit that was fun to play with.

Oh, forgot. It's against the neocons' religion to play, if no one gets hurt.

Thanks, Rich

Reply to
Richard The Dreaded Libertaria

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