Transister Legs

[Crowded Ghost]

Hey all,
At the moment i am building a transmitter and reciever for a remote control car for my year 12 major assessment. I am having problems with the legs on two of the transisters. So my question is what are the C B and E legs on a B564AY and a D471AY. If you dont know, could u give me a way to find out.

Crowded Ghost

 

[Exo]

I can't find those transistors so i assume they're japanese and the 2S prefix is left away...

so they are 2SB564AY
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and
2SD471AY
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If these are not the transistors you're talking about then nm...

 

[zachtheterrible]

A handy little tool to find out what you want to know can be bought @ radioshack for $5. I use it quite a bit. It not only tells you the legs, but it tests scr's, fet's, diodes, etc. I think it's just called a transistor tester.

 

[Crowded Ghost]

Thanks very much guys for your help u have done more than u think. thank u again.

Crowded Ghost

 

[pike]

I thought you could do this by looking at the package type that the transistor is encased in. to-92, to-3...

no point now. Anyhoo...

 

[ChrisP]

I thought you could do this by looking at the package type that the transistor is encased in. to-92, to-3...

Not always... all that the case type really specifies is dimensional aspects of the device, e.g. physical size, shape, and where the leads are placed. It does not necessarily specify which lead is in which position -- just where the leads will be physically located dimensionally.

Consider the fact that many transistor replacement (cross-reference) lists will indicate that one device may be an exact replacement for another, while some other device in the same case type may be a suitable replacement electrically but not physically. This is generally because the leads are not placed in the same relative orientations.

For example, on the TO-92 case, Pin1 is always the left-most pin when holding the device with the leads pointing downward and looking at the "flat" side of the device. This places Pin 2 in the center, and Pin 3 to the right. TO-92 transistors generally use E-B-C (1-2-3) lead orientations, but clearly not always!

Look at the image below. This is a capture of the top of the datasheet for the Fairchild KSA733, a PNP transistor in a TO-92 case. Look carefully at the bulleted notes under the device description. It is offered by Fairchild in two versions, with the only difference being lead orientation:

• KSA733 - Pin 1 E, Pin 2 B, Pin 3 C, and
• KSA733-C - Pin 1 E, Pin 2 C, Pin 3 B.

Two electrically identical but physically different devices with the same base type number (KSA733) from the same manufacturer! Yeh -- you can't really assume lead assignments by case types...

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