[46] Leaky AC128 Transistor Buffer Test

Date: September 24th, 2007 | Comments : [4] | Categories: DIY.

Scope pic of buffer output

Leaky AC128 Transistor Buffer Test

Here is a bad picture of the output of the AC128 buffer that was described in the previous article. It is a 2v pk-pk, 100kHz triangle wave going through the exact setup shown in the schematic. The response is flat from 10 to 100kHz and beyond – excellent performance. This test was run with the leaky PNP transistor operating on a 9v battery.

I tested 10 leaky AC128s and got identical performance from all of them, with current leakage measured in the range of 400uA to 700uA.


4 Responses to “Leaky AC128 Transistor Buffer Test”

[85] Robert Keeley Says: 5:50 am, October 7th, 2007

Great Oscope bro! Is that you that I can see in the reflection?!?! That scope reminds me of some of the US Navy stuff that I had to use in repair shops early on. BK Precision makes great test gear. I was surprised by how well those transistors worked being leaky, then got to think, those devices were used all of the time in radio/RF circuits so they HAD to perform to that level as a minimum.
Good work Jack!

[86] amz-fx Says: 8:45 am, October 7th, 2007

I’ve owned the B&K for more than 25 years and it was not new when I bought it in a pawn shop. It still works great!


[2549] Anton Says: 8:14 pm, January 1st, 2012

Hey Jack! Does forward gain (bias) matter on the device? I’ve got a ton of PNP devices and the gain is rather low?

[2562] admin Says: 10:04 am, January 3rd, 2012

The beta is part of input impedance equation and the higher the hfe, the greater the input Z will be.

regards, Jack


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