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7805 IC

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New Member
Im fairly new to electronics and i'v got a few components that im going to play with to get a hands on feeling of how they work. So i want to know how to hook up the 7805.

Can someone draw up a quick schematic of what i need to connect to what pins to change a voltage from ?v to 5v

What is the maximum voltage i can supply to the regulator if itis not heat sinked?


Active Member
All the things you ask depend on the package. 7805 is available in 4 diffirent packages i know off (possibly more)

I will give an example for the most used package - TO220 (see pic)

Apply GND to the middle pin, Your input voltage at the first pin and 5V out is on 3rd pin.

In this package it is rated 100mA uncooled - 1A with (large) cooling
It had a thermal protection and short circuit detection but i wouldn't rely too much on it.



New Member
Thanx that is the package that i am using and i assembled it on a protoboard and hooked it up like you said. Worked great! Then i added a 332K ohm load across Pin 3(output) and ground and measured the voltage across it. Still worked like it should it put out a steady 5v. Well not exactly it was more like 4.97 or something. Im guessing this is close enough for goverment work.

Thanks for the help


New Member

:D hi squintz,

as an added protection against short circuits both in the input and output you can shunt a IN4001 across the output and input for input short circuit and shunt another IN4001 across the output and ground for output short circuit.

as what crust have said dont rely too much in its built in protection. :D


Well not exactly it was more like 4.97 or something.
Bear in mind, when you take that measurement, that your voltmeter will never give a perfect reading, as it has it's own calibration tolerance (usually between 0.2-2.0%, depending on the model)


New Member
this is the simplest way to hookup

this is the way...it is very simple.


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