Transistor Vbe Matching Using A Commutating Chopper-Based Circuit

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mediatechnology
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Re: Transistor Vbe Matching Using A Commutating Chopper-Based Circuit

Post by mediatechnology » Wed Oct 07, 2020 2:01 pm

I finally got the Vbe Matcher off of a Protoboard by moving it to Vectorboard.

It's been awhile since I did point-to-point Vectorboard.

The connections across the top are Power, 'Scope Monitor Out (filtered), Output to A/D, 1.5 mV P-P Calibration signal, 15V Trigger output.

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The two jumpers and shunts switch the test socket from NPN to PNP.

There are two rows in the test socket.
The right-hand row is for CBE pinout transistors.
The left-hand row is for BCE pinouts.

Image

The clip is to thermally equalize the test transistors.

A pair of BD139 BCE pinout transistors:

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A 2SB737 pair:

Image

One more project I can check off the list...
It's been a productive few weeks.
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
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User avatar
mediatechnology
Posts: 4696
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
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Re: Transistor Vbe Matching Using A Commutating Chopper-Based Circuit

Post by mediatechnology » Thu Oct 08, 2020 12:54 pm

JR. wrote:
Sun Dec 22, 2019 9:38 am
If you add a 50k or so resistor from the junction of the two emitters to ground that would prevent potential reversed junctions from zenering when switched for the wrong polarity.

JR
I added D1-D4 to clamp Ve.
Not only for the reason JR gives but also to reduce recovery time for when both devices are removed from the test socket.
Without D1-D4 Ve goes to the rail when Q1 and Q2 are removed.

Image
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4

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