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voltage regulator...*updated with pics*

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Omegachi

Diamond Member
i need to use a voltage regulator for a project of mine, and i am not sure how i works. I got a 7805CT chip and i am not sure how the pinouts work. I tried looking for the pinouts but couldn't find it, i could only get discription of the chip. and also, why do people use a capacitor with the voltage regulator? is it to keep the regulator (or the path out of the regulator) with a constant voltage?



*update* scroll down to my other reply.
 
Capacitors are used to smooth and help regulate input/output voltages. At least, that's one use.

As for your pinout question.. They're most likely all the same, unless otherwise noted. Just find the standard pinout for a voltage regulator.
 
Originally posted by: Omegachi
i need to use a voltage regulator for a project of mine, and i am not sure how i works. I got a 7805CT chip and i am not sure how the pinouts work. I tried looking for the pinouts but couldn't find it, i could only get discription of the chip. and also, why do people use a capacitor with the voltage regulator? is it to keep the regulator (or the path out of the regulator) with a constant voltage?
Click to expand...

7805 is simple. looking straight at it, the left pin is Vin. The center pin is ground. The right pin is Vout. That's it. Put 7-30 VDC on the input, and you get 5VDC regulated on the output. If you need more info, go to the National semiconductor web page.
 
Just go to the data sheet link and look over the suggested schematic. For starters, that's all you need. However, take into account the low drop out voltage (LDO) of the regulator. It's usually around 1V. It just means how much more voltage you would need to input from your rated output voltage in order to maintain regulation. As for the capacitors, they are used to decouple the AC signals. Why? Because there are still some slight variations (voltage goes up or down a bit) at the output. You want as close to a pure DC signal as possible. Usually the caps are hooked straight to ground. You can look at it this way: caps look like a piece of wire as the frequency goes up; AC signals involve frequency.
 
Originally posted by: Qacer
Just go to the data sheet link and look over the suggested schematic. For starters, that's all you need. However, take into account the low drop out voltage (LDO) of the regulator. It's usually around 1V. It just means how much more voltage you would need to input from your rated output voltage in order to maintain regulation. As for the capacitors, they are used to decouple the AC signals. Why? Because there are still some slight variations (voltage goes up or down a bit) at the output. You want as close to a pure DC signal as possible. Usually the caps are hooked straight to ground. You can look at it this way: caps look like a piece of wire as the frequency goes up; AC signals involve frequency.
Click to expand...

so i hook the cap in series with to ground from the regulator?
 
so i hook the cap in series with to ground from the regulator?
Click to expand...

NO! The cap goes between the output voltage and ground. Since Caps block DC current you will have no output current if you put it in series with the output current path.
 
ignore the transistor types i have in the diagrams...


so what i can understand, this is how you connect the cap? click
*update* oops, i meant to connect the input to the ground. my schematics is wrong.



and to test if a transistor is working (not burnt out from soldering) is this how i test it? click

the transistors i used are already soldered on to the board.
 
Originally posted by: Omegachi
so what i can understand, this is how you connect the cap? click



and to test if a transistor is working (not burnt out from soldering) is this how i test it? click

the transistors i used are already soldered on to the board.
Click to expand...

Sorry but I don't understand what the NPN transistor has to do with the 7805?

Connect the Cap between the IN voltage and ground and the other Cap between the OUT voltage and ground.



 
Originally posted by: Omegachi
oops, my schematics is wrong. i meant to connect the input to the ground.
Click to expand...


OK, but I still don't get it. The 7805 is nothing like the NPN transistor. Looks like you are using Circuitmaker?
There is a symbol for the 7805 in there.
 
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