I'm pretty bad at analyzing equivalent transistors and recently I bought some at a local store, but only today I realized that the ones they gave me don't seem to be equivalent, so I need to know if a BC237B can substitute a BC548.

 

hi spike,
What circuit are you using that requires a BC type change.?
E

 

As all bipolar transistors work the same way, any transistor can, within reason, be substituted for any other transistor of the same polarity.
Just check the following:
Is the voltage rating Vceo high enough?
Can it take the power?
Does it have enough gain? (Hfe)
Does it have enough frequency response? (Ft)
and, perhaps,
are the pins in the same place?

They don’t have to match precisely, just to be higher or the same.

if you understand the circuit into which you are substituting the transistor, you can check not whether the new transistor matches the old, but whether the new transistor will work in the circuit.

very occasionally you will encounter a poorly-designed circuit where the operation depends on the transistor having a low Hfe, and your substitution might not work.

 

https://www.newark.com/on-semicondu...jt-npn-30v-v-br-ceo/dp/82C0450?CMP=AFC-SF-BNL

 

The two transistors are both NPN silicon and they have the same pinout and packaging. Unless they are in a critical circuit section they are probably near enough matched.

 

It's for this circuit.

Datasheets:
BC237B
BC548

Also, I wonder: can anyone tell me if there's anything wrong with the circuit by just looking at what's written and shown? I had someone criticizing the IC used, but I don't thing there's anything wrong at all.

 

hi spike,
In that circuit comparing the parameters of the two transistors, they will be OK as an equivalent.
E

 

@erickgibbs What's "Equivalent E"? You mean that I can use the BC237B just fine?

 

It's for this circuit.

The author told you the only specific requirement was beta:

 

hi spike,
Yes, it is OK to use.
E is my name initial letter.

 

@dl324 Which value is beta (β)?

@ericgibbs Ok, thank you very much sir.

 

Which value is beta (β)?

hFE. That spec sheet is incomplete. Beta is specified as a range and at specific circuit conditions.

 

hi spike,
I do not see a problem, if you are in doubt, make up a simple test circuit board and try the BC548's

E

 

I would not sweat over this. Just about any Si NPN transistor will do, such as 2N3904.

 

Hello,

In the old days ELEKTOR used "universal" transistors and diodes.
They called the TUN TUP DUS and DUG:

Bertus

 

@ericgibbs I was told that the vertical and horizontal syncs are not required if I'm going to use the amplifier on the tv's neckboard, meaning that the lm1881 and the 74l221 will be discarded, thus being a waste of time and resources if I use them.