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Author Topic: Need transistor math and theory  (Read 4202 times)

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Offline TrickyNekroTopic starter

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Need transistor math and theory
« on: August 28, 2008, 07:53:15 AM »
Hello guys,


Same as title.... on both PNP and NPN transistors...
I found some NPN calculators but nothing more...

I need to build some transistor based circuitry and I want to calculate some resistor values
although I can place them based on experience, cause I'm dealling with more than one or two transistors...

Hope you can help,
Best Regards, Lefteris
Greece
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline benji

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Re: Need transistor math and theory
« Reply #1 on: August 28, 2008, 10:27:37 AM »
whats the circuit ya wanna builld?
good ol' BeNNy

Offline ArcMan

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Re: Need transistor math and theory
« Reply #2 on: August 28, 2008, 12:58:22 PM »

Offline TrickyNekroTopic starter

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Re: Need transistor math and theory
« Reply #3 on: August 28, 2008, 06:10:31 PM »
whats the circuit ya wanna builld?

Well, just for effect I want to place a bidirectional LED on the RESET line of my micro...
When micro is working LED would be green, but when programming or reseting it would be RED

I came with a circuit of four transistors and I'll upload the schematics soon enough!!!
I only want to calc some resistors before testing.... so that I don't burn 'em...
Not that they cost me something only time getting downtown to buy new....


Anyways, thank you both for the interest!!!
Best Regards, Lefteris
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline benji

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Re: Need transistor math and theory
« Reply #4 on: August 29, 2008, 04:37:41 AM »
as long as you want it to be only a switch the math would be easy...

the BC547 is widely used  in switching
good ol' BeNNy

Offline RobD

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Re: Need transistor math and theory
« Reply #5 on: August 29, 2008, 11:28:09 PM »
Transistor Bias....

Three letters - PNP - "positive negative positive"

1.  The first letter P =  "positive emitter"

2.  Second letter N = "negative base"

3.  Third letter P = "emitter more Positive than the base"

It's the opposite for NPN's  ( for example - 3.  base more positive than emitter)



« Last Edit: August 29, 2008, 11:38:07 PM by RobD »

 


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