Suitable PNP/NPN transistor replacement selection process

[Potato Cakes]

Hello!

I'm currently trying to find a suitable PNP transistor for a BC212L that is ECB configuration (facing the front). I'm comparing the various specs from the BC212L data sheet with those that are in current production, and the closest I've found is the PN4355. The one difference I see is the collector-emitter saturation voltage which for the BC212L is 0.6V and the PN4355 is listed as 0.5V. Is that 0.1V that big of a difference in an audio circuit?

Thanks!

Paul

 

[JohnRoberts]

Hello!

I'm currently trying to find a suitable PNP transistor for a BC212L that is ECB configuration (facing the front). I'm comparing the various specs from the BC212L data sheet with those that are in current production, and the closest I've found is the PN4355. The one difference I see is the collector-emitter saturation voltage which for the BC212L is 0.6V and the PN4355 is listed as 0.5V. Is that 0.1V that big of a difference in an audio circuit?

Thanks!

Paul

No... Saturation voltage mainly matters if you operate it as a saturated switch. Typical audio applications are not saturated.

What can matter is
1- breakdown voltage : must be enough to not exceed typical specified max voltage in use (to keep smoke inside).

2-beta or HFE: should have adequate current gain. How much is adequate depends on the application. Current gain is evaluated for nominal operating currents.

3-NF: Noise figure is a combination measure of equivalent input noise compared to a perfect resistance (lower is better, but should be compared wrt expected source impedance).

4-Rbb: base resistance, an advanced audio spec for very low noise transistors (lower Rbb is better).

5- more: There are far more specifications that matter for different applications.

JR

 

[Potato Cakes]

Thank you, JR.

With my exceptionally limited understanding of what electrons do when go out and party, I was just trying match values as best that I could. This information will be very helpful when I have to replace other obsolete transistors.

I went ahead and ordered some 4355s.

Thanks!

Paul