help on transistor tester

What on Earth are you doing Guest?

Why use a micro just to test transistors?

I think you should start with something a little less complex. What you're trying to do is quite ambitious. If you persevere then follow the lessons came with your starter kit! Some are pretty powerful to learn from especially Lesson 4: Analog-to-Digital in your case.

What do you want actually, a tr. tester or going into programming?

Which is it? You don't know how to write a program or you don't know how to test a transistor? If you know how to test a transistor, then creating the program is easy, if you know how.

Vulcan is right, you should be first clear about what your are trying to do. If you know what to and how measure the voltages for testing the transistor rest is easy. Please send me details of the kind of test you are conducting and expected results may be I can help as I am also a Microcontroler enthusiast, of course just learning, but I know more of programming than the Microcontroller itself.

ok.. actually i just wanna know how to write the programs.. basically i know how to test the transistors..

the problem is i don't know how to write them.. im using mplab.. C language.. n using PIC simulator Ide to simulate it..

im testing for types of transistors(npn, pnp)

determine hfe where users get to choose what current ratings they want(ie:1mA, 10mA...)

determine the three legs of x'sistors( b, c, e)

determine Vbe(sat), Ic(sat)

test whether the x'sistors and diode are faulty.. if yes, show dynamic and static resistance of the diode..

additional info:

only bjt x'sistors are tested..

using pic 16f877a

4 x 4 keypad

2 x 16 lcd

measuring current, voltage with adc of pic..

currently building my current circuitry..

deadline: 2 weeks from now..

pls do help.. i really need some help n advice.. ty^^

Dear Guest,

It seems that ganapa will help you to write code but you must supply a circuit for him to help you.

The key point is that to form a common point for voltages that you will measure.

Say you measure the DC beta of tr. First you will measure Vemitter (=RexIe).

You know that Ie=Ib+Ic. Then You must measure voltage on Rc that represents Ic but it will be referenced to VCC not ground!. For this reason you will measure Vcollector (to ground). Then Vce = Vc-Ve and Ic = (Vcc-Vc)/Rc and Ib= (Ve/Re)-Ic and hfe=Ic/Ib.

Note that in this calculations the Vcc and the Re and the Rc are PARAMETERS. If one of them is changed then the current values (that they will be calculated via coding) will be changed!.

Think in this wise and constitute a circuit and send it to ganapa that he can help you for coding.

Good luck...

there are many advises above. all is very good, you will accept carefully.

you may be a software programmer, this is a good idea to program a auto test transistor instrument.

but you have to know any sotware has to base on the hardware. if you dont know the structure of hardware, no software will exist.

besides above threads reply. I suggest you learn, wht the a/d and d/a acts in the testing.

what is step wave and how does it act in auto transistor tester

how to use a half wave rectifier to construct a collector power

how much di/dt and dv/dt is the broken throw crisis point

what is volume resistor in a transistor and basic parameter said by above threads.

then you can write your sostware. thats very easy to get it.

besides, there were lots of such eaxmple worte in the past in basic language. refer to

After all the good information from various other posters, may I suggest that you either buy or make a transistor tester (one that is simple to build, but without any computer interfacing), then, once it is working correctly, change the hardware to allow you to interface it to your PIC.

This way, you will be able to make sure that the values your PIC displays (I assume that you have an LCD display or similar for your results) are the same as the tester would measure without/before the PIC......

In fact, it might prove possible to have both displays running for a time till your interface and software are fully proved out.

Its a hard way to start but once you have licked it, you will be in a very good state to attack anything else that you might want to build using a PIC!

I wish you well.