Hifibythekg
Super Member
Great thread Doug. Incredibly helpful explanations and a great resource. Well done!
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dlucy’s guide to transistor testers and curve tracers
- Thread starter dlucy
- Start date
Digital Multimeters (DMM) for testing transistors
What is it?
A DMM (digital multimeter) is one of the basic necessities for working on solid state gear to measure voltage, resistance and current. There are thousands of different models, they've been made for decades, all have some basic functions which would help us, and some have more advanced functions which apply specifically to transistor testing.
What does a digital multimeter (DMM) do?
Typically, a DMM will
What does a digital multimeter (DMM) not do?
under construction
How to find Base, Emitter, Collector of a BJT transistor with
Multi-meter DMM
How to test transistors with ANY multi-meter DMM
How to test a silicon transistor with a multi-meter using the diode function. and how to tell if it is a PNP or NPN and find the Base
How to Test Transistors with a Multimeter - NPN, PNP, JFET
Links to more information
What is it?
A DMM (digital multimeter) is one of the basic necessities for working on solid state gear to measure voltage, resistance and current. There are thousands of different models, they've been made for decades, all have some basic functions which would help us, and some have more advanced functions which apply specifically to transistor testing.
What does a digital multimeter (DMM) do?
Typically, a DMM will
- Measure resistance
- Measure voltage, usually AC and DC
- Measure current
- Measure conductivity (meaning it will BEEP if a component flows electricity and will remain silent when it is open)
- Test transistors
- Display hFE or gain
- Remain silent when the transistor is dead
What does a digital multimeter (DMM) not do?
under construction
How to find Base, Emitter, Collector of a BJT transistor with
Multi-meter DMM
How to test transistors with ANY multi-meter DMM
How to test a silicon transistor with a multi-meter using the diode function. and how to tell if it is a PNP or NPN and find the Base
How to Test Transistors with a Multimeter - NPN, PNP, JFET
Links to more information
- Testing hFE or gain with a multimeter or DMM ( @rickl )
- Tips on using a DMM for transistor testing ( Jon_Logan )
- Another tip on using a multimeter for transistor testing ( @Leestereo )
- BJT transistor testing basics (including with DMM) ( echowars )
- Testing BJT transistors for shorts or opens ( @avionic )
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Heathkit IT-1121 semiconductor curve tracer
What is it?
The Heathkit IT-1121 semiconductor curve tracer accurately measures the operating parameters of virtually all types of discrete semiconductors - gain (beta), leakage, breakdown voltage, saturation, forward conduction voltage, output admittance, linearity, capacitance effects, temperature effects, etc.
The IT-1121 can also be used to select devices for specific design applications: for sorting, inspecting, and testing semiconductors, and for troubleshooting.
What does the Heathkit IT-1121 semiconductor curve tracer do?
After you attach a semiconductor to the IT-1121 and an oscilloscope to its outputs, you set the tester to run varying voltages and currents through the device-under-test and this results in curves being displayed on the oscilloscope.
The curves show how the device-under-test will perform under these varying in-circuit conditions. From the curves displayed, you, the circuit designer, would know "is this transistor the best one for my design" or "what do I need to design in my circuit so this transistor does what I want it to do".
Tip: the IT-1121 has two transistor sockets and allows you to flip back and forth between them to assist in matching two actual transistors. One bit in this video explains that capability.
What does the Heathkit IT-1121 not do?
Links about it
What is it?
The Heathkit IT-1121 semiconductor curve tracer accurately measures the operating parameters of virtually all types of discrete semiconductors - gain (beta), leakage, breakdown voltage, saturation, forward conduction voltage, output admittance, linearity, capacitance effects, temperature effects, etc.
The IT-1121 can also be used to select devices for specific design applications: for sorting, inspecting, and testing semiconductors, and for troubleshooting.
What does the Heathkit IT-1121 semiconductor curve tracer do?
After you attach a semiconductor to the IT-1121 and an oscilloscope to its outputs, you set the tester to run varying voltages and currents through the device-under-test and this results in curves being displayed on the oscilloscope.
The curves show how the device-under-test will perform under these varying in-circuit conditions. From the curves displayed, you, the circuit designer, would know "is this transistor the best one for my design" or "what do I need to design in my circuit so this transistor does what I want it to do".
Tip: the IT-1121 has two transistor sockets and allows you to flip back and forth between them to assist in matching two actual transistors. One bit in this video explains that capability.
What does the Heathkit IT-1121 not do?
- It does not display its results by itself; you need an oscilloscope with X-Y inputs to see the curves
- It does not handle very low current devices (doesn't go low enough in sensitivity/steps)
Links about it
- How to use the IT-1121 ( @Doug G. )
- In-depth thread and videos on repairing the Heathkit IT-1121
- Heathkit IT-1121 assembly manual
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That two-transistor-socket capability to flip back and forth between them while displaying curves is really, really useful!
catrafter
Marantz Specialist
Lots of great info here!
For troubleshooting solid state power amps with negative feedback, the Huntron or the so called Octopus is great for finding bad components.
I have a couple of curve tracers for matching and finding proper substitute semiconductors, after reading the data sheet for the basic parameters of course.
Thank you , Doug!
For troubleshooting solid state power amps with negative feedback, the Huntron or the so called Octopus is great for finding bad components.
I have a couple of curve tracers for matching and finding proper substitute semiconductors, after reading the data sheet for the basic parameters of course.
Thank you , Doug!
The Sencore Super Cricket should get some light. Old school, out of circuit tester, excellent for uncovering transistors that test OK on a meter or the Atlas. It can find leaking transistors. It is AC powered and has various power levels for testing.
Word is getting out and prices are jumping.
Anyone with X-Y ability on an o-scope should rig up an octopus. I found the suggestion here and the thread had a link to DIY schematics. I came up with a beefy 3V transformer and with a few leads and a few resistors had one of the handiest tools on the bench. Being able to locate questionable or dead transistors and diodes in circuit while unpowered is stupid handy. It’s pretty much the only thing I use one of my scopes for.
Word is getting out and prices are jumping.
Anyone with X-Y ability on an o-scope should rig up an octopus. I found the suggestion here and the thread had a link to DIY schematics. I came up with a beefy 3V transformer and with a few leads and a few resistors had one of the handiest tools on the bench. Being able to locate questionable or dead transistors and diodes in circuit while unpowered is stupid handy. It’s pretty much the only thing I use one of my scopes for.
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Sencore Super Cricket
What is it?
The TF30 Super Cricket is Sencore's "ultimate" transistor tester (as per the manual). It can perform a basic good/bad test without removing the transistor form the circuit and it can test for gain and leakage and more precise parameters when used out-of-circuit.
You don't need to know the basing diagram, the polarity, or even if the device-under-test is a BJT or FET.
There is also a portable version, the TF46 Super Cricket Portable
What does a Sencore Super Cricket transistor tester do?
What does it not do?
What is it?
The TF30 Super Cricket is Sencore's "ultimate" transistor tester (as per the manual). It can perform a basic good/bad test without removing the transistor form the circuit and it can test for gain and leakage and more precise parameters when used out-of-circuit.
You don't need to know the basing diagram, the polarity, or even if the device-under-test is a BJT or FET.
There is also a portable version, the TF46 Super Cricket Portable
What does a Sencore Super Cricket transistor tester do?
- Test any transistor or FET
- In-circuit good/bad test
- Out-of-circuit parameter test
- Automatic lead coding and basing selection
- Audible and visual test indication
What does it not do?
- under construction
- @blhagstrom comments about the Super Cricket
- TF30 Super Cricket transistor tester manual (attached as a PDF)
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Doug G.
Lunatic Member
Sorry I have taken so long to write more about the Heathkit IT-1121 but I have been trying to remember exactly how I used it and I still haven't fully, it's been so many years.
However, I basically set all the controls (horizontal/vertical sensitivity, voltage-per-step, etc) on it to coincide with the transistor parameters and for each type we were testing (it was an incoming product situation), we had a standard and set the curve tracer up to display the curves satisfactorily. Then we plugged the incoming transistors in and were able to see, by the curve they made, whether or not they met the minimum gain requirements.
Of course, with this unit, you need to have an oscilloscope connected to display the curves as there is no display in the unit, itself. Also, it was strictly for out-of-circuit use. You couldn't connect it to an in-circuit transistor and expect accurate results.
After set up, it was easy to use, however. In fact, I made overlays to hold up to the oscilloscope screen and trained the QA gals how to check the incoming transistors, themselves and they had no problem.
Another thing I just remembered, we made a modification to it because some of the transistors (used in hearing aids) were very low current devices and the standard IT-1121 didn't go low enough in sensitivity/steps so a little circuit was added and a separate switch added to test those particular transistors. Of course, this would not be necessary with the usual transistors used in Hi-Fi equipment.
Doug
However, I basically set all the controls (horizontal/vertical sensitivity, voltage-per-step, etc) on it to coincide with the transistor parameters and for each type we were testing (it was an incoming product situation), we had a standard and set the curve tracer up to display the curves satisfactorily. Then we plugged the incoming transistors in and were able to see, by the curve they made, whether or not they met the minimum gain requirements.
Of course, with this unit, you need to have an oscilloscope connected to display the curves as there is no display in the unit, itself. Also, it was strictly for out-of-circuit use. You couldn't connect it to an in-circuit transistor and expect accurate results.
After set up, it was easy to use, however. In fact, I made overlays to hold up to the oscilloscope screen and trained the QA gals how to check the incoming transistors, themselves and they had no problem.
Another thing I just remembered, we made a modification to it because some of the transistors (used in hearing aids) were very low current devices and the standard IT-1121 didn't go low enough in sensitivity/steps so a little circuit was added and a separate switch added to test those particular transistors. Of course, this would not be necessary with the usual transistors used in Hi-Fi equipment.
Doug
Yamaha5000
Never settle for 2nd best
I have a 3.7V Inductance Coil Capacitor ESR Meter MG328 Multifunction Transistor Tester N, when testing a device I always receive a message in regard to calibration. It also states to visit a web site for additional details. I don't understand the calibration procedure and the web site is not located. Can anyone shed some light on this?
I have also used my Heathkit IT-1121 to test small signal vacuum tubes (12AX7, etc.). Of course, to do this one has to add an external heater supply.
please share how you did that here.
these are the overall cheap component tester instructions I bookmarked. Do these work for your unit? https://www.mikrocontroller.net/attachment/164956/ttester_eng104k.pdf
My workbench is down for the time being. All I can offer is a photo of the setup that I took a while back.
Yamaha5000
Never settle for 2nd best
What are your thoughts on this curve tracer?
https://www.ebay.com/itm/163909738013?ul_noapp=true
https://www.ebay.com/itm/163909738013?ul_noapp=true
Just my limited-experience, hobbyist perspective here:
That is a tracker, not a transistor curve tracer. That just means it would be OK for in-circuit fuzzy troubleshooting, but not for curve tracing (comparing the actual performance curves, at diff voltages and currents, of one or more transistors. The big clue, for me, is it only has two input terminals instead of three. I.e doesn't do transistor curve tracing as that requires all three leads of the transistor-under-test to be connected.
What is it you want to accomplish? Troubleshooting? Then a tracker could be useful, certainly fun. Comparing transistors during circuit design? A proper curve tracer would be better.
DIY kits from ebay are perfectly OK way to go. I've bought and built several, just never used them.
PTL-Pioneer
Super Member
Doug, thank you for this, great work, I'm very grateful, bookmarked!
Yamaha5000
Never settle for 2nd best
How does the Heathkit IT-121 fit into the product line?
Yamaha5000
Never settle for 2nd best
This one arrived the other day and was assembled last night. Pretty straight forward, but I thought these testers were supposed to show a difference between a Zener diode and a regular one. I tried with known (just out of Mouser bag) 1n4148 vs a 13V Zener and wouldn't know that the one was a zener from the display. Any tricks?