1-Do I have to calibrate my system or is it done yet?
2-I installed a 2sa970 and got the message 'parameters have get from device', then 'saved' but during the next step 'load conditions' I have a blank window with no pre-defined mesure conditions. What should I do?
Thanks for your help,
No need to calibrate,Because the .ini file in compress file is calibrated.
The ads7871_v3s.pre in your file folder?
I just moved files to program directory and it works now! I measured a hfe of 3.5 for the 2sa970! I will investigate and ask you if I cannot find the problem.
Do I have to shut down the system each time I want to test a new transistor?
Many thanks
Missing voltage?
Hi all,
Trying to measure some 2sa970 (the first test in the manual) I get Hfe of 2.5 only! Even if the datas column indicates average value of 9.9V for VCE I can actualy measure 0.3 V on the board. I only have 45 mv on the base of Q1 and Q2, 215 mv at the emitters and 0.5V at the 'C' output after J1 relay. Any idea to help me?
Many thanks.
Hi all,
Trying to measure some 2sa970 (the first test in the manual) I get Hfe of 2.5 only! Even if the datas column indicates average value of 9.9V for VCE I can actualy measure 0.3 V on the board. I only have 45 mv on the base of Q1 and Q2, 215 mv at the emitters and 0.5V at the 'C' output after J1 relay. Any idea to help me?
Many thanks.
Locky_z,
I have an issue with the curve tracer and it seems others have as well.
When measuring JFETs the IDss measured by curve tracer is
on average 1mA at least above what we get by the DMM test with a 9V battery for example.
So PC curve tracer is useless this way, can we calibrate it so it gives reliable Idss values ?
I have an issue with the curve tracer and it seems others have as well.
When measuring JFETs the IDss measured by curve tracer is
on average 1mA at least above what we get by the DMM test with a 9V battery for example.
So PC curve tracer is useless this way, can we calibrate it so it gives reliable Idss values ?
Ceevee,
I have found the same thing, but when testing in reverse, (meaning I test already matched by battery method), the tracer gives an excellent view of very well matched traces. In truth, I don't think the curve tracer does much for us with these small signal jfets other than finding perfectly aligned curves, which seem to be easily found. I think it speaks to the quality of the Toshiba parts. Try heating up teh jfets and then tracing them and see if you get seperation of curves.
I have found the same thing, but when testing in reverse, (meaning I test already matched by battery method), the tracer gives an excellent view of very well matched traces. In truth, I don't think the curve tracer does much for us with these small signal jfets other than finding perfectly aligned curves, which seem to be easily found. I think it speaks to the quality of the Toshiba parts. Try heating up teh jfets and then tracing them and see if you get seperation of curves.
The 2sa970 component foot is right?
Send the save data(.cuv) to me.
When start the measurement, the system control 3 channel output only moment of voltage.
When measure finish, 3 channel output to 0.
If you want to measure 3 channel output voltage by DMM, you can select menu 'option->diagnoosis' and 'Device Test' page -> 'Voltage Test' box,
Set the 3 channel output voltage and click the 'Output' button,
Then you can get the static voltage.
Send the save data(.cuv) to me.
When start the measurement, the system control 3 channel output only moment of voltage.
When measure finish, 3 channel output to 0.
If you want to measure 3 channel output voltage by DMM, you can select menu 'option->diagnoosis' and 'Device Test' page -> 'Voltage Test' box,
Set the 3 channel output voltage and click the 'Output' button,
Then you can get the static voltage.
Hi Buzzford,
That is what i use it extensively for; comparative Transfer curve matching after DMM matching,
That way i have a reliable Idss value and use the curve tracer for Rdgen fine tuning for example with 2SJ74BLs and 2SK170BLs.
I just brought this up because it would be nice if we could rely on it's measured Idss instead of having to use DMM matching beforehand.
Yes I find the same Idss "offset", but no - the tracer is not useless because of this.
Rather, I would say that it works very nicely if you want to match curves and/or estimate transconductance. In relative terms it is very accurate and deliver very reproducible measurements. Perfect for the hobbyist - and useless for professionals
A simple way of absolute calibration would of course be very nice.
Are you talking about SK170/SJ74 curve matching? While NN and PP matches are rather easy to find I can assure you that this is not the case for NP. The tracer comes in very handy here
I would rather say that it could be much improved in the high current functionality...
My suggestion:
First trace and match the devices based on these data (for example using virtual in silico degeneration of the J74).
Then sort the matched sets by measuring Idss at equilibrium.
To convince yourself that this really works try to measure Idss "the old way", but now with degeneration.
I am very, very pleased with the result
Yes, your are right.The reason is that Curve Tracer measured tiny voltage not precision.
When you get the Vgs-Id curve , from the curve ,The X-axis(Vgs)=0,The y-axis is Idss.
Although the X-axis = 0, but actually Vgs may be plus/minus a few millivolts.
The 'Offset test' button functin is to show the tiny voltage measure error,
When the button click,system will short the B-E / C-E / RC /RB by relay J6 J7. This mean Vbe=Vce=Vrc=Vrb is ture equal 0V, but the measure value may be not zero.
Because the four voltages will be affected by the impact of the 'Ve' voltage and the temperature. So system will draw four curve 'Ve->Vbe'/'Ve->Vce'/'Ve->Vrb'/'Ve->Vrc' curve.
To reduce the error, you can check the 'Calibration before measure' checkBox,
When It is checked, The system will calibration first and then do the curve measure.
My suggestion:
First trace and match the devices based on these data (for example using virtual in silico degeneration of the J74).
Then sort the matched sets by measuring Idss at equilibrium.
To convince yourself that this really works try to measure Idss "the old way", but now with degeneration.
I am very, very pleased with the result
Glad to get your feedback on that Nic,
thanks
I was speaking of NN and PP. Of course NP is a whole different ball game. I love the tracer, just pointing out that it is not optimal for Idss measurement and the battery test works great. I have used it to sort matched Idss fets fro better curve alignment. In this regard it excels. I think it might be one of my most valuable tools in electronics.Yes I find the same Idss "offset", but no - the tracer is not useless because of this.
Rather, I would say that it works very nicely if you want to match curves and/or estimate transconductance. In relative terms it is very accurate and deliver very reproducible measurements. Perfect for the hobbyist - and useless for professionals
A simple way of absolute calibration would of course be very nice.
Are you talking about SK170/SJ74 curve matching? While NN and PP matches are rather easy to find I can assure you that this is not the case for NP. The tracer comes in very handy here
I would rather say that it could be much improved in the high current functionality...
Guess i was just aiming for a little too much
i use it exactly like you guys and it is indeed very handy at comparative transfer curve matching once i have done the DMM matching on a little PCB i have built where i plug in the P and N fets.I found it particularly nice at dialing in the Rdgen on the 2SJ74s and comparing the curve interactively with the matching 2sk170s.
i had some doubts about the reliability of what i was seeing on the laptop but your validation as well as Nics give me the reassurance i needed.
thanks.
True.
But even easier:
1) Trace all the FETS without any kind of degeneration.
2) From the traces sort and record Id @ 0V and 0.1V
3) Copy to excel (and fix all the stupid decimal and errors
)4) Calculate Yfs = (Id@0V-Id@0.1V)/0.1V
5) Recalculate Idss and Yfs for the J74 using selected Rdeg values (I use 4R3, 4R7, 5R1, 5R6, 6R2, 6R8 and 7R5).
Congratulations! - you now have 7 times as many J74 devices to choose from
6) Match you K170 and degenerated J74 devices for both Idss and Yfs.
7) Remeasure (or trace) the pairs/sets you have identified, but now with degeneration and be ready for a pleasant surprise
True.
But even easier:
1) Trace all the FETS without any kind of degeneration.
2) From the traces sort and record Id @ 0V and 0.1V
3) Copy to excel (and fix all the stupid decimal and errors
4) Calculate Yfs = (Id@0V-Id@0.1V)/0.1V
5) Recalculate Idss and Yfs for the J74 using selected Rdeg values (I use 4R3, 4R7, 5R1, 5R6, 6R2, 6R8 and 7R5).
Congratulations! - you now have 7 times as many J74 devices to choose from
6) Match you K170 and degenerated J74 devices for both Idss and Yfs.
7) Remeasure (or trace) the pairs/sets you have identified, but now with degeneration and be ready for a pleasant surprise
Thanks Nic,But...Rdegen trick comes at a price....slightly higher distortion, read this somewhere !, and according to Patrick ( EUVL ) deviating from 5R1 is to be avoided.
I fail to understand this but then that will be because i don't know enough of the subject.
My reasoning was in line with what you just laid out, the lower the Rdegen needed the better i thought. 5R1 being an average value.
I'd love to get the facts on this.
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