I have 3 extra of Mark's boards that I'll mail to anyone interested. One board each to the the first three individuals that PM me. North America residences only.
This is probably a dumb question because I'm really good at asking those, but I'm going to ask anyway....
If one wanted to try to match P to N BJT's, can this be done with this circuit? Set a reference P-channel for instance, and then cycle through N-channels until a match is found? Feel free to tell my why it's a dumb question. I'm expecting that
If one wanted to try to match P to N BJT's, can this be done with this circuit? Set a reference P-channel for instance, and then cycle through N-channels until a match is found? Feel free to tell my why it's a dumb question. I'm expecting that
This board will let you match (NPN_Vbe) against AbsoluteValue(PNP_Vbe), yes. If the NPN_Vbe happens to be +0.6111 and if the PNP_Vbe happens to be -0.6116 then the meter will read ±0.0005 volts, sign depends on which one is plugged into the left side socket and which one is plugged into the right side socket.
However, ask yourself the harder question: is VBE_Mismatch what you actually want, between PNP's and NPN's ?
What sort of circuit works best when a PNP transistor has exactly the same AbsoluteValue(Vbe) as an NPN transistor?
Perhaps your circuit wants the PNP and NPN to have identical current gain (Beta) instead? If so then this Simple VBE Matcher is the wrong tool for the job.
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However, ask yourself the harder question: is VBE_Mismatch what you actually want, between PNP's and NPN's ?
What sort of circuit works best when a PNP transistor has exactly the same AbsoluteValue(Vbe) as an NPN transistor?
Perhaps your circuit wants the PNP and NPN to have identical current gain (Beta) instead? If so then this Simple VBE Matcher is the wrong tool for the job.
_
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Thanks Mark. I know I am dumb with a lot of this stuff, but asking my dumb question made me a little smarter thanks to you. Thank you for humoring my ignorance.
I can attest the clothes pin works great. I use a plastic one and place a small piece of foam over the transistors then clamp them. Stabilizes extremely fast. The board I'm using allows the faces of the transistors to touch each other.
@DualTriode We're you able to get the BJT Simple Matcher PCB to measure JFETs using your approach in post #22? I am looking to measure some J113 parts for the M2x IPS6 and wondered if I can utilize a spare BJT Simple Matcher board for this purpose as you had suggested. Im still too much of a noob to feel confident I can figure this out on my own without destroying a bunch of JFETs.
Thanks in advance for any advice.
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Hello @birdbox , you can study (and perhaps copy) the exact setup I used to measure J113 parts for the experimental prototypes of the M2x IPS6 card.
Check out M2x post # 3,377 and notice the 2nd attachment; my JFET measurement frobb can easily be implemented on a solderless breadboard. That message was posted on August 12th. Seven days later, on August 19th, I published the schematic and Gerbers for IPS6 in post 3,408.
You can use just about any NPN transistor in the jig; ZTX696B is simply what I had in hand at the time. Beta>100 is desirable and Vcemax >= 20V is essential. Even the humble 2N3904 / PN2222A / BC547 would be acceptable.
Check out M2x post # 3,377 and notice the 2nd attachment; my JFET measurement frobb can easily be implemented on a solderless breadboard. That message was posted on August 12th. Seven days later, on August 19th, I published the schematic and Gerbers for IPS6 in post 3,408.
You can use just about any NPN transistor in the jig; ZTX696B is simply what I had in hand at the time. Beta>100 is desirable and Vcemax >= 20V is essential. Even the humble 2N3904 / PN2222A / BC547 would be acceptable.
TL431s are so cheap and so darn useful, that I bought hundreds of them just to have handy in the lab. Then I discovered the AS431AZ (Mouser link), an improved version of the chip from Diodes Inc, with much tighter output voltage tolerance and incredibly low price. So I bought hundreds of those too. USD 12.00 for 250 parts is a screaming bargain if you ask me.
No I did not assemble the PCB that Mark offered at Burning-amp. think of wheatstone-bridge.
https://www.grc.nasa.gov/www/k-12/airplane/tunwheat.html
I sketched up something similar on a 5x7 file card. I wanted to use a couple of those lever operated sockets rather than the pin type sockets.
I use a keysight bench power supply to set and limit voltage & current so not to destroy too many parts in the process.
Go ahead and break some parts, J113's are plentiful and cheap by the 100.
DT