Question about transistors

[mrbanana]

It's been a while since I did any real electronics at school, so apologies if this a stupid question.
I'm trying to make a duplicate of a fairly simple circuit that makes test tones and the like. It was built over 30 years ago, so I'm not sure if all the components are still available. I've not had any problems with the resistors or capacitors, but the transistors I can find for sale don't quite match up with what I have, and this is where my electronics knowledge is letting me down.
There are three kinds of transistors, marked as: BC 213 LB m, BC 213 LB r and BC 183 LB (I can't even read this last letter clearly - it's either a, d or q)
I can find BC 213L, BC 183, BC 183C and BC 183LC.
So my question is, what is the significance of the last letter(s), and if they are very important, does anyone know where I might be able to obtain the transistors that I need.
Thanks.

 

[Russlk]

The letter L appears to signify a lower Ft than the transistor with no letter. However, these are general purpose PNP and NPN transistors, so the common type that you found should work fine. Alternate transistors would be 2N3906 and 2N3904 (pinout may be different).

 

[mrbanana]

Thanks for the information.
At about 5p each, I guess I can try them with no real loss if they don't work.

 

[Nigel Goodwin]

Thanks for the information.
At about 5p each, I guess I can try them with no real loss if they don't work.

Try posting the circuit that you're building, it's common that the transistor type isn't at all critical - the vast majority of circuits will work with any general purpose transistors.

 

[mrbanana]

If I could remember how to draw a proper circuit diagram, I would!
It is (I think) a pretty simple circuit that generates a tone and allows you to modulate it a bit.
Once I've fathomed out exactly which kind of switches that I need, I'll have everything and can start building it.
Thanks for the advice.

 

[Edmond]

The last letter refers to the noise factor.
Last letter: nothing: standard, without noise specification
Last letter: A: this type has got a biggest noise
Last letter: B: this type has got a middle noise.
Last letter: C: this type has got a low noise.

For the numeric specifications use the datasheet.