Author Topic: Noob Question on Transistors  (Read 810 times)

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Offline VegaObscuraTopic starter

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Noob Question on Transistors
« on: June 28, 2009, 07:56:32 AM »
I've spent nearly a week trying to figure out how to use them.  I'm not talking about anything fancy, I just want to use one as a switch.  In this learning experiment I want to have a battery going to a led, with a transistor controlling whether its on or off.  I intend to have another power source going to a button which then goes to the transistor to turn the transistor on or off.  Here's the part that I can't understand.  Transistors have 3 pins.  That just fries my brain.  If transistors were a 4 pin component, it would be easy to comprehend.  + and - of the circuit to be turned on and off by the transistor would connect to the 2 pins on one side, while the circuit turning the transistor itself on and off would connect to the other 2 pins.  But that's obviously not how it works, since they have 3 pins.  Everywhere I try to read about them loves to talk about the fact that they can be used as switches or can be used to amplify current, but I can't find anywhere telling about how to actually use them in a circuit.

Offline Razor Concepts

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Re: Noob Question on Transistors
« Reply #1 on: June 28, 2009, 08:00:06 AM »
http://www.allaboutcircuits.com/vol_3/chpt_4/2.html

The circuit turning the transistor on/off does not need 2 pins since the ground is common with the circuit to be turned off/on.

Offline VegaObscuraTopic starter

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Re: Noob Question on Transistors
« Reply #2 on: June 28, 2009, 08:19:40 AM »
Okay, I think I understand.  So let's say the side with the battery and led is circuit 1.  The battery and button is circuit 2.  So I should connect + from circuit 1 to one pin, + from circuit 2 to another pin, and ground from both circuits to the third pin?  That's a little hard for me to comprehend, but I think I got it.

 


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