Made a little voltage regulator circuit

Among the things which came in the “value pack” of linear circuit ICs from Futurlec are some voltage regulators. While trying to figure out what to do with them, I came across this site:

How Electronic Gates Work.

Along the way to getting you started with TTL gates, it shows how to use a voltage regulator to get a +5V supply from something else, like a 15V supply.

Digging around in the data sheets for the L7805CV voltage regulator, I found similar circuits though with MUCH lower values for the capacitors. Apparently the particular value used isn’t all that critical. The data sheets gave very low values, but also said that those should be solid tantalum capacitors, and if aluminum electrolytic capacitors were used, the values should be increased by at least 10x.

Anyway, here’s my little circuit:

And here’s a shot of the oscilloscope showing 5v coming out. I’m powering the circuit with a 15v DC wall wart transformer I had lying around.
(a little out of focus, oh well.)

In the process of this I seem to have busted my voltmeter. I think it happened when I tried to measure the output voltage of the transformer (15 v, according to the scope, and what it says on the transformer itself.) I’m not sure why that would have smoked it, but it no longer measures voltage, and the ohm-meter is busted too, it seems to think it’s always shorted, which sucks because the continuity tester function is pretty useful. Hoping I just blew a fuse, but it seems odd that a 15V 1-amp max would blow the thing., or that while measuring 15v, that the thing would even draw any appreciable current at all. Oh well, it doesn’t seem to work anymore. (Edit: I replaced a fuse, and it works again.)

I also have 12V and 6V and 15V regulators, so I could make similar circuits with those, add some toggle switches and LED indicators and make a little DC power supply that does 5, 6, 12, and 15v.

~ by scaryreasoner on July 11, 2009.

One Response to “Made a little voltage regulator circuit”

  1. toggle switches are very handy specially if your project requires momentary on switch…

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