FET as linear mode heater

As long as the T-loop is not too fast :^) I do this trick with diode laser where you modulate the diode current and the grating angle in phase. At sorta 1-10 Hz rates. If the thermal loop was too fast it would fight the current modulation.

George H.

Bill I'm not trying to "pile on", but I agree with Phil. You are getting much to cranky. (I mostly find myself just skipping over your replies.)

George h.

Our interaction does seem to have degenerated from the one to the other - a nd since I'm now complaining about it, I've managed to demonstrate the capa city to effect this discrimination in this particular case.

But you do want to have the last word, even when that last word hasn't got much to do with the subject under discussion.

I object to incorrect posts. The skewering is incidental.

Odd. Your posts are rarely incorrect, and if you make an error - as we all do from time to time - I remain well aware that you are one the most reliab le sources around here.

The proportion of political rubbish rose. You'll still find helpful and con structive posts from me, from time to time, but they represent a smaller pr oportion of my output. I worry more about anthropogenic global warming than I used to, and John Larkin reposts more denialist propaganda than he used to.

I'm not interested in looking like anything in particular - I'm not looking for potential customers any more, and I've never been someone to flatter p otential allies, no matter how much I admire their electronic skills.

But if it were that fast, you could modulate the setpoint instead. ;)

Cheers

Phil Hobbs

Senility? Some of us "age" retaining our "think like an 18 year old" (but then I falls asleep ;-) minds" , others, like Slowman... ...Jim Thompson

Most transistors, bipolar or fets, will melt solder before they fail. Mosfets go berzerk at a bit past 300C, basically turning on with no gate drive. They tend to fail hard a little past that.

There's a strong tendency for all of us to turn into caricatures of ourselves as we age. Fighting it helps (hint, hint).

Cheers

Phil Hobbs

I don't take "bait" anymore, do I?

But Slowman's circuit comments are mostly just so f**king dumb... "emitter _pushing_", and edward.ming.lee's, "Growing wafers takes time and money".

Sheeeesh! How's an ol' fart to cope with such nonsense ?>:-} ...Jim Thompson

Which is ironic, because flies are actually much more attracted to vinegar (it's a product of biological decomposition, after all). Our parents lied to us; and taking the analogy further: the effectiveness of trolls on the internet and elsewhere bears this out.

Tim

Yeah, that's good when you have more power to dissipate than the transistor can handle -- a load dump for example. You can about double the capacity for a given transistor, saving some bucks on heatsinking and all that.

Tim

I'll be interested to see your experimental results on YouTube. ;)

Cheers

Phil Hobbs

current.

ohm power resistor in series, with feedback from the resistor to control th e current.

the

hing closer

asier to control.

atter.

why not a buck-converter away from the sensitive stuff and just the resistor inside the probe?

-Lasse

No need; others have reproduced it. :)

As for the troll aspect, YouTube also provides proof in the famed quality of their comments. ;-)

Tim

Also, that was an interesting workaround. OE, in its infinite wisdom -- of course -- is not RFC compliant, so it happily stacks References in the header. Which you can't edit from within OE. So at just the right stage in this highly-stacked thread, it sends the massive line, and eternal-september in my case bounces it (441 error).

The workaround I saw was, save the original message, edit the plaintext in Notepad to remove extra references, then reply to that.

(If these replies end up in some bizarre place in your newsreader's threading, I guess you can actually blame it on me personally?)

In over a decade, this is the first time I've ever seen this happen. Weird.

Tim

Yep. I just tried the scheme of taking a 2-liter soda bottle, cutting off the top, inverting it into the bottom (funnel-style) and filling it part way with vinegar and sugar mix... works fairly well.

The problem seems to be that the flies only come when we are on the patio, doing a steak :-(

Next trial... fill with Coke and some raw hamburger... I suspect that will be the ticket. ...Jim Thompson

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

Perhaps a combination of CO2 and mixed partial combustion products (smoke, burnt flesh, caramelization products)?

It'll catch *something*, all right :-p

Tim

Exactly. I just don't get all of this wasted BW for something so simple..

Actually, you can build it in the head of the unit with a high enough switching freq to keep components small.

Jamie

Once you filter it, you're back to yhe quadratic case.

Cheers

Phil Hobbs

On Monday, May 4, 2015 at 4:09:46 PM UTC-4, Lasse Langwadt Christensen wrot e:

ax current.

n the

ething closer

easier to control.

matter.

er,

Yeah sure, (I think the short answer is because I've mostly only read about SMPS.) So to get power control I would change the duty cycle of the buck? What sort of dynamic range can you get?

I was thinking I should make a PWM heater too, with just resistors.

Oh that brings to mind a question. (perhaps simple?) What's the easiest voltage to duty cycle converter. (OK, uC's or some other controller... but after that.)

George H.