I've got this circuit sketched up to use a FET as heater/ temp sensor (to measure heat capacity of stuff... pulse heat, measure delta T.) I'd run current backwards through the FET and use the body diode to measure T. The same thing could be used to measure how fast the fet cools. That would tell you a lot about the thermal path/ properties. You can only measure T when the FET is off, which is a disadvantage.
I haven't tried it yet.
George H.
No, just briefly cut off the heating power and measure the b-e junction as a thermometer. That can be done in microseconds.
Mosfets can use the substrate diode.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
You can buy thin-film platinum RTDs in 0805 and 1206 packages and use them to simulate the static and dynamic thermals of resistors soldered to PC boards.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Huh, OK I never thought of that.. or had to worry about it. I've never used platinum RTD's, (I think I bought some wire wound years ago, but never used them.... besides semi checking dR/dT when they came in.
Re: measuring the temp of the pass element. I was thinking of (designing for) ms to second time scales. On the detector side of the FET, I had everything buffered by
1.5 k ohm lnd150's, a current source and int. amp. Power side is, power supply, fet, sense R, ground. with opamp feeding fet, sensing R, current is Vin/R. Energy is V_suppy*current*pulse_time. (at some point you care about the power in the sense R.)George H.
Basically brute froce. Froce is an extra strong force, if you didn't know. :^)
Brute farce.
You can do the temperature measurement of the substrate diode with just some DC current through a resistor, and an oscilloscope. Switch the drain from the power/heat supply to ground for the measurement.
The old Tek differential-comparator plugins were fabulous for this sort of measurement, but most any decent scope will do.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Well that too, just don't tell my customers.
OK or do it that simpler way... The hard part about using a diode temp sensor is calibrating the diode.
George H.
Just do the measurement part, and take a few voltages at a few temperatures. It will be pretty linear between points. The measurement current can be low, so self-heating will be minimal.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Can it figure out why my girlfriend's apartment is so cold in winter even with the heat cranked up? It has high ceilings and a lot of windows. My suspicion is that whoever did the renovation prior to the current landlord purchasing it simply cheaped out on the BTUS/square foot.
You need a thermal camera or an infrared thermometer.
-- -TV
IP
can
to the
time, and with good reasons.
Evince, Gedit, Firefox, Gedit/Gimp/(some office suite I don't even know whi ch), GIMP, I don't, *, Firefox. It all runs on Linux, and not an .exe to be seen.
*: I don't do the pcb layouts or embedded softwareOne of the reasons the main linux distros have gone to such great trouble t o compile their own extensive application software respositories is that do wnloading exes from 3rd party sites has been a major source of malware for windows users. And no, that's not just from fringe sites & dodgy authors. T he whole process is inherently vulnerable.
You might not agree, but almost nobody will download some .exe someone else posts, even with the best of intentions.
NT
Those things are binary executables that you download from the web. Linux just uses a different filename convention.
What do you do?
OK, don't run my program. I just might be evil and want to take over your PC and steal your valuable circuits.
But you don't seem to design electronics, so you are safe from my nasty schemes.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Guys design houses to be cold so girls need to snuggle up.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Aren't AMD CPUs immune?
Cheers, James Arthur
They have valid concerns John. After all, you have been known to write code in uppercase.
Grins, James
Most of my engineers run Linux [1], but Win7 works fine so I have no reason to convert now. I'm comfortable with all the engineering tools that I've acquired and developed, and too busy designing circuits to cut over. I guess I am crotchety in that I am annoyed with a continuous stream of gadgets and apps with weird UIs and strange internal states and faddish (now all grey) color schemes.
I don't do weird stuff so don't acquire malware.
[1] with some version of Windows on a VM.-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Zero. Visiting certain classes of web sites is far more dangerous than running my 26 kbyte compiled Basic program.
It's amazing to see how many people live in fear, and assess risk so irrationally.
And aren't interested in electronic design.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
If one should follow from the other, then clearly we have a contradiction here, and he is not?
JL's never shown any inclination against feeding trolls -- or realizing that you win internet arguments by /not/ replying -- in the 2+ decades he's been on Usenet. A "better engineer" would learn that lesson; more likely, he simply enjoys it. (You know, the old joke about arguing?..)
I don't mean this as an offense, to either of you; merely a statement of historical facts. Also, given historical evidence, the worst response I would expect from JL (if this is taken as an insult) is either "oh yeah well what did you design today?" or "at least I designed and sold x% dollars of THING$". (And just to round things out, yes, this provides still further evidence to the historical fact of my frankness to a fault. So, things continue not to change, no surprise there, eh?)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
There are several people that I always ignore.
A "better engineer" would learn that lesson; more likely, he
It would be nice if this was an electronics design discussion group, and not an inferior version of my-o-my twitter.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Because they don't give him the flattery he feels he deserves.
Then we'd have to stop John Larkin posting his recipes here.
-- Bill Sloman, Sydney
ZIP
C)
it can
n to the
.g time, and with good reasons.
hich), GIMP, I don't, *, Firefox. It all runs on Linux, and not an .exe to be seen.
KiCad runs under Linux, and Linux offers a huge rage of compilers.
to compile their own extensive application software respositories is that downloading exes from 3rd party sites has been a major source of malware fo r windows users. And no, that's not just from fringe sites & dodgy authors. The whole process is inherently vulnerable.
se posts, even with the best of intentions.
Linux repositories do seem to be acceptable sources of safe software - they are programs that "somebody else" has posted, but the posting process does seem to be fairly tightly controlled.
-- Bill Sloman, Sydney
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