they make Dc-DC converters for that so that you can not only isolate but you can generate dual rail supply from a single rail. Look for DC-DC converters with + & - output
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"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
Hi, Ken. You can connect two batteries in series as mentioned by Pete S. Connect the - terminal of battery 1 to the + terminal of battery
Then, the + of battery 1 will be +12V, the connection will be 0V or common, and the - terminal of battery 2 will be -12V. That may be the easiest way to do it, and is probably the best way to go for a newbie. It also has the inherent advantage of very low power supply noise and no ripple.
There are a number of "clever" ways to do this, which don't require lugging around two gel cell batteries (kind of heavy, take up quite a bit of space). You can use a DC-to-DC converter, which will convert
4.5V or 6V (three or 4 AA or C batteries) into the +/-12V you need.
Mouser has the Datel BST-12/105-D5 3 watt W DC-DC converter that will do this job, for $28.60 in single quantity.
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Or you can use two 555s to build a voltage doubler and a voltage inverter to convert +6V into +/-12V (less a couple of diode drops). But both of these solutions will add power supply noise considerations into your circuit that you might not need.
Most old split supply op amps like the venerable (and practically obsolete) LM741 are specified for "balanced" split supplies, but they'll work perfectly well as long as both supplies are more than 3V higher/lower than the input voltage range. I don't believe this was true for the uA709, LM101 or some of the real fossils, but they're gone, anyway (thank St. Liebowitz!).
I'm wondering, though, whether you might better spend your time looking at other options, if your project isn't "in the can". Single supply op amps have been very common for over twenty five years. Most anything you can do with the old split supply op amps can also be done with single supply ICs with a little craftiness. And that will solve your problem of portable split supplies.
If you care to post again with more information, you might learn how you can run your project on a single supply with three or four AA batteries.
From the other helpful posts and some additional web searching, it appears that this is a fairly hot topic and the component manufacturers offer various solutions -- none of which have been implemented in a resonably-priced retail package. Designing a circuit from scratch around some of these chips is beyond my abilities.
The kits mentioned in the eBay ad require an AC source; this is not helpful as I won't have A/C in the field. 9-13.8V DC is available.
Yes, very interesting. Any idea how much curerent I could put through the Sijosae splitter? That looks like a $1 solution. The splitters with active compnents all look like $10+ solutions.
for what you're doing the TLE2426 alone has enough to drive your Op-amp.. they are commonly used for some things like that. they are only 20ma how ever, i don't think you'll be using that much any ways and they regulate well.
--
"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
In addition to the other posts, is it possible to run the circuit in question on +/- 9V? Many op amps circuits are perfectly happy with this, as long as you are not asking them to go too close to the rails. And those little batteries sure are small and convenient!
Best regards,
Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis
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Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!
Hi John, I see these "circuit lists" posted often, I'm new to LTspice and don't know how to insert such a list into the program. What steps do I take to run the simulation you posted. Thanks, Mike
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Use something like Notepad to copy the list into to a convenient
directory, renaming it anything-you-like.asc, and then navigate to
it with LTSPICE and click on the file.
When the schematic comes up, right click anywhere there\'s no
component and then click on \'Run\'
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