Urgently Need Transistor Equivalent

[thothset]

please tell equivalent transistors for the following ...which can easily available and little bit cheap..


2П307B

2Т203А

2Т203Б

2Т203Г

2Т608Б

and because i'm nerd, please help me
1. how to find a equivalent. for example: what are the parameter to check between original transistor and equivalent? how can i judge that particular transistor is best equivalent.
2.Is application of transistor plays a role to find equivalent transistors? eg. switching and amplification etc..

please educate me.

 

[shrtrnd]

We use manufacturer data sheets.

 

[thothset]

We use manufacturer data sheets.

how to analyze the manufacturer data sheets to find equivalent

 

[davenn]

how to analyze the manufacturer data sheets to find equivalent

look specifically at the voltage and current ratings

 

[thothset]

look specifically at the voltage and current ratings

ratings should be higher or lower than original?

 

[davenn]

ratings should be higher or lower than original?

what do you think ?

 

[thothset]

what do you think ?

1.polarity must be same eg. NPN will only match with NPN.
2.max voltage of Vcb,Vce,Veb
3.Max current of Ic
4.Max power Pd
5. Hfe
anything else?

 

[davenn]

1.polarity must be same eg. NPN will only match with NPN.
2.max voltage of Vcb,Vce,Veb
3.Max current of Ic
4.Max power Pd
5. Hfe
anything else?

yup
another words .... rated at least the same as the old transistor, doesn't matter is the ratings are a bit higher

 

[(*steve*)]

anything else?

The most important thing is whatever is important in the circuit. There is rarely a single "best" equivalent unless the same transistor is manufactured by multiple sources (in which case they are likely to have very similar part numbers).