Hi all,
I have to add a ripple voltage (1Vrms) in serie to a 24V Battery (to build a test bench). The current is about 30A. I was wondering if a transformer in serie with the battery could do the job.
Cheers, H.
Yes, it can if it is designed to handle the DC current through the winding. This usually means a core with a magnetic gap.
You need to seriously consider dropping out of the profession, you're worthless at electronics and always have been.
The DC is likely to saturate the transformer core unless the transformer is over-sized. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
Not with a bridge rect. Damn, can I explain this without drawing it ?
Find a tansformer that only puts out like 3 VAC or so, put a bridge on it w ith shitty filtering and just add it to the battery voltage. If they want r ipple, which is obviously to be able to tell if a device is vulnerable to r ipple, they are not worried about an extra volt. So three volts AC, minus t wo junction drops per the bridge rectifier will give you about a volt lefto ver.
Problem is finding the right transformer. With such a stepp voltage and thu s impedance ratio, it is not a hard transformer to design and have the curr ent level required. The PROBLEM is there is about no market for such transf ormer so as such it might be very hard to find one.
Try Digikey's selector thingie, who knows if they have one. Just because I can't think of an application for the thing doesn't mean there isn't one. h owever I would be interestied in where this particular demand might be othe r than in this case right here, which is a bit unusual. The whole world is trying to get rid of ripple and here we are...
So ~ a one ohm load? What frequency? Could you just couple it in with a capacitor? Or a diode?
George H.
Ah yes with an air gap magnetic core in order to avoid saturation. Good ide a. I have simulating this configuration with femm.info.
Habib.
ild a test bench). The current is about 30A. I was wondering if a transform er in serie with the battery could do the job.
thless at electronics and always have been.
ok i will, but you have not appreciate my joke "tchou tchou" about your inc ompetence on the design of a the high voltage indicator.
Habib.
At Test Labs, or to make a local setup, we used tostick a 500VA transformer in series, One of those 'fliament transformers, or for doing a 'sweep' a difficult to find now "Power Audio" matching transformer, tube to speaker step down. I think they'll take the DC current bias. And if you must use two.
PS: put in series with the GND of the system so you can easily read the amount of ripple you're injecting.
H.-
As noted, 30 Amps DC is likely to saturate a transformer. If you can solve that problem, it should work. Use a "variac" to provide an adjustable voltage to the transformer primary.
Why not use a regulated power supply instead? It would be easier to modulate a linear voltage regulator to provide ripple. Modulation could be provided either by a signal generator, or by a transformer fed from the mains.
Fred
Yeah, just like bloggsy.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Sure. How much ripple do you need? What frequency?
A series inductor would work, too, the advantage being that you can buy an inductor that is spec'd for that much DC.
You could do it with mosfets, too, if you can tolerate a little DC voltage loss. Switch on/off, maybe.
Transformer is easiest.
-- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
That should work even on a switching supply, if the bandwidth is adequate.
Both a linear and a switching supply will suffer from being one-quadrant devices -- they're generally only designed for one polarity of current, and one polarity of voltage. As long as the ripple voltage is modest enough that the current is always being drawn out of the supply, and never sunk, this should work.
You may even be able to trick an off the shelf supply (the kind with voltage sense inputs) into doing this. But maybe not, and if not it'd be wasted time. I'd be inclined to just get a humongous 28V supply, a handful of 2N3055's, and start whomping up something big and dangerous.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Yea, take any doughnut ring core main transformer, put 24 volt lead through it, if it manages to saturate add some small DC through the primary in the opposite direction.
An NMOS and an OpAmp will do it easily, IF you can stand the slight drop. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Absolutely! Wound my own transformer for that and found the transformer was good to 80A all by itself.
and/or gapped as suggested.
You could possibly have another winding that bucks out the DC component in the secondary. If the DC buck winding has 30 times the turns of the secondary, then you only need 1 A through that winding.
Jon
:
build a test bench). The current is about 30A. I was wondering if a transfo rmer in serie with the battery could do the job.
orthless at electronics and always have been.
ncompetence on the design of a the high voltage indicator.
It's spelled choo-choo in U.S., goes to show you're not even at kindergarte n level here. And there's only about a hundred billion hand calculators in service that a re powered by PV as their only energy source that do just fine and withstan d all kinds of abuse in handling and operating environment, so you're dead in the water on that criticism. Gawd only knows how your demented mind inte rprets "dead in the water."
Uh-huh, just because a person doesn't use electronics as part of their con game, doesn't make them worthless.
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