Programmable Voltage Source Idea

wtf???? How come this circuit looks bogus to me???

D from BC snipped-for-privacy@comic.com British Columbia Canada

It's sideways. All the electrons will fall out the bottom.

James Arthur

Just looking at the 339 makes me ill..

My idea of a programmable V source uses a DAC.

D from BC snipped-for-privacy@comic.com British Columbia Canada

And didn't they leave out the rotating magnets ?:-)

...Jim Thompson

Yep. It's gonna oscillate something fierce.

"D from A C" ?

Grins, James Arthur

Yes, great catch. They did leave those out--and that's the tie-in to mpm's free energy machine, the centerpiece of our new green/renewable feelings-based energy agenda.

Cheers, James Arthur

Where is the (programming) input and where is the output?

You left out lots of important starting detail like:

- how you want to "program" it

- what voltage range you need

- what you mean by "medium power"

That circuit is silly BTW.

"Abstract Dissonance" - we haven't seen you here in a while...

Dave.

Okay, you haven't gotten many straight answers, so I'll take a stab.

No, your circuit won't work. The LM339 is a comparator; it'll oscillate in that circuit. The MOSFET might oscillate too.

You can use an LM339 as a lousy op-amp, but it'd be better to just use a decent op-amp. Or an LM317.

You'd get more sensible answers if you showed input and output nodes and said something about your goals and needs (accuracy, range, power output, load, etc.)

HTH, James Arthur

Well, I figured since you guys are so intelligent you would be able to figure out what is going on. It is suppose to be a comparator and not an op amp. It is not a difficult circuit to understand. Seeing how rude the people are here it's not even worth trying to explain. I'll come back in another two years and maybe the trash will have been taken out. If anyone can't figure out the circuit then maybe they need to go to sci.electronics.basic and hang out for a while. The circuit works fine in practice and I'm not sure what your talking about with oscillation. The comparator should oscillate to some degree and with a bit of built in hysteresis it should be fine. Do you seriously thing that the opamp/comparator matters? That alone tells me either you guys don't care to pay attention and just want to be jerks. I used the lm339 because that is what multi-sim had. Abstract thinking is important but I guess they don't teach that in repair school? See you guys in two years, hopefully you will have grown up by then.

It actually is difficult to understand.

I don't understand how a 10k pot will handle 100 volts without burning up, or why a circuit that's supposed to be programmable doesn't have a programming input. Or an output.

I don't understand why you'd think that the LM339 has built-in hysteresis--it doesn't.

I don't understand why the apparent reference input to this voltage regulator from hell is nailed to +5.5v, which makes the whole thing look kind of useless.

I don't understand why you're using such a complicated circuit to perform such a simple function so poorly.

I don't know why you had to go to all this trouble just to fry a pot and a zener diode--is it a race perhaps? To see which one will smoke first?

But that's just me.

James Arthur

No no no...that's not the right attitude.. . You're getting free advice! You got my free 30 second analysis..You get what you pay for..

You'll peak interest and get more feedback if you format your schematic for the purists and list advantages and write a summary. Otherwise you'll just get mush. GIGO

Heck, just list your specs..Some guys on here have done every fkn way to do a circuit. btw..I hate circuit analysis and prefer circuit synthesis.. Circuit synthesis is like being an artist. Circuit analysis is like being a janitor that cleans up a mess... Sorry but when I looked at your circuit, it seemed like a janitorial operation.

D from BC snipped-for-privacy@comic.com British Columbia Canada

(sci.electronics.basics added, at Dookie's suggestion)

Dookie wrote: > On Nov 7, 2:34 pm, James Arthur wrote: >> snipped-for-privacy@gmail.com wrote: >>>

It actually is difficult to understand.

I don't understand how a 10k pot will handle 100 volts without burning up, or why a circuit that's supposed to be programmable doesn't have a programming input. Or an output.

I don't understand why you'd think that the LM339 has built-in hysteresis--it doesn't.

I don't understand why the apparent reference input to this voltage regulator from hell is nailed to +5.5v, which makes the whole thing look kind of useless.

I don't understand why you're using such a complicated circuit to perform such a simple function so poorly.

I don't understand why you had to go to all this trouble just to fry a pot and a zener diode--is it a contest? A race to see which one will smoke first?

But that's just me.

James Arthur

I don't understand the person.. If I can't understand the person, there's a good chance I won't understand the circuit either.

D from BC snipped-for-privacy@comic.com British Columbia Canada

A schematic reads like a window into its author's soul. You can understand a lot.

I don't understand someone asking for critique, then complaining when he gets it.

Cheers, James Arthur

If it works fine in practice, why did your original post ask us if it would work in practice? It's really goofy, but I suppose it might regulate. Some.

Bye. See you in 2010.

John

That comparator pointing up is like a raised middle finger.

John

Is "Dookie" a nom de plume for Jon Slaughter ?:-)

What is with all these amateurs seeking assistance then getting all huffy when questioned?

...Jim Thompson