you've "switched gears" here several times between running your device from an AC supply and a battery. which is it? or is the battery a backup supply if the power goes out? is there a problem with the circuit running on 12V or is it running on 10V because it's maxing out a 12V wall wart? if it's running on 10V because it's drawing too much current from the wall wart, then build a 12V regulated supply for it that can supply 3A, and have the battery backup available directly(after the regulator) if the power goes out. i don't see any logical reason the circuit can't run off of 12V.
They look a lot like the suggestions in posts #2, #4, and #7. The regulation needs to be good with an input voltage of 11.5V, so those circuits won't work here.Here is a little different spin on increasing current
High Current Voltage Regulation - Electric Circuit
Problems:get a second battery, wire the batteries in series for 24V
The output voltages of 3 pin regs are pretty good these days with the new manufacturing tech or laser trimming or whatever they do. It's trivial to measure the output voltage and with 7805 (even cheap ones) they are rarely out of the range 4.96 - 5.08 or about 0.12v variation, and often better when from the same batch often within 40mV or less.
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where do you buy your regulators? Fantasyland??? I just built 4 test fixtures and I had (4) brand new 78L05s with the same date code, bought at the same time, and they were all over the place. The only reason I checked was part of the test fixture had a thermocouple input calibration circuit on it, so I used a precision source for that circuit. On a production run of 1000 boards, you'll find the full range of the +/- .4V. We've built systems where we have 70000 units in the field. I once did a statistical plot on a run of a 1000 boards (too much time on my hands). You couldn't have drawn a better bell curve. They set the parametric specs for a very specific reason. If they could repeatably manufacture CHEAP parts with that tight a spec they would have them spec'd that way. You could even 'grade' them, say, buy 100 and measure the voltage under a standard load and pick two that had the same voltage output, but come back in an hour, and they could be off... they might not have the same temp. drift... you should NEVER parallel two voltage regulator outputs, 'cept through a diode or a FET, for dual redundant, not double the current.
Consider yourself thoroughly 'jumped'...
And.... a fully turned on transistor has a VBE of .7v, but the knee starts at .6v, that's why in the previous message 5 ohm yielded .12A. I always use .6v when I calculate current limiting resistors. Here is a circuit I use, the one on the left. I adapted it from the data sheet of, YES, the 7805. Look at the output stage of the 7805 and compare that to the circuit on the right.
I have confirmation of the LT1528 having been shipped, but I'm still waiting for her...
Meanwhile, If I'm making a 10VDC 3A power supply, I would think after the bridge rectifier's dropout, that a 14V transformer would be sufficient. Should I go for the 16V?
Either way, tell me if I'm wrong, but I can't have the transformer exceed 3A output (14V...42watt, 16V...48watt), or I risk damaging the rectifier if I HAPPEN to try to draw more than 3 amps, correct???
Hey Mr. Odom, I'm glad to see you have plenty of energy available to jump MrRB, do you have a little energy left to answer my most recent inquiries?
If you're using a 14v secondary on a transformer and a full wave bridge, you're going to see something like 19V on the DC coming from the cap
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