You drive around with your foot on the brake pedal until the brakes feel like mush and there is smoke and a very bad fishy smell coming out of the wheel arches
I think they smell more like burnt hair than fish.
Hfe dependence on Vce
akis,
I checked a bunch of my bjt models for ft and Hfe vs Vce and Ic during the
ft discussion. Most of the ft's were pretty close but overall the hfe versus
vce is pretty poorly represented. This was most prominent with high volatge
devices, at much higher vce's, say >100V, hfe was much higher than I've
ever measured.
At the end of the day, I think it pays to probe through your simmed circuit
and get a feel for how sensitive the results, for example distortion, are to
hfe variation of various devices.
Still I agree with you, it would be nice to have more accurate models.
I'd be interested in your results and thanks for the effort.
T
Ahhh I see. I do hope to be able to find some time to do some serious testing this weekend on a variety of trnasistors and then I will report here. But my bench supply only goes up to 2 A
akis,
I checked a bunch of my bjt models for ft and Hfe vs Vce and Ic during the
ft discussion. Most of the ft's were pretty close but overall the hfe versus
vce is pretty poorly represented. This was most prominent with high volatge
devices, at much higher vce's, say >100V, hfe was much higher than I've
ever measured.
At the end of the day, I think it pays to probe through your simmed circuit
and get a feel for how sensitive the results, for example distortion, are to
hfe variation of various devices.
Still I agree with you, it would be nice to have more accurate models.
I'd be interested in your results and thanks for the effort.
T
Wondering, syn08, if you have any experience with the Agilent 4156C; any cautions, issues, etc. with the unit?
Agilent | 4156C Precision Semiconductor Parameter Analyzer
Modeling Tube Designs with Altium Designer
Hi all!
After smashing my head against the wall for quite some time, I have been finally able to get the Altium Designer working correctly with Koren tube models.
As this has been quit a hazzle, I put together a how-to and included some actual simulation files as well.
Please feel free to send me comments and corrections, so I can acommodate all the wisdom to the document!
The article itself can be found at
Modeling tube circuits with Altium Designer.pdf
Regards,
Andrus.
Hi all!
After smashing my head against the wall for quite some time, I have been finally able to get the Altium Designer working correctly with Koren tube models.
As this has been quit a hazzle, I put together a how-to and included some actual simulation files as well.
Please feel free to send me comments and corrections, so I can acommodate all the wisdom to the document!
The article itself can be found at
Modeling tube circuits with Altium Designer.pdf
Regards,
Andrus.
Is this simulation parameter correct?
In all Spice models of MJE182 that i have download from On Semi site (PSpice, Saber, Spice2, Spice3) its parameter "Saturation Current" is given as "IS = 1e-17". When i put this value in the corresponding box of parameter table of the EDSpice Simulator that i use, is translated automatically (and correctly) in IS = 0.01 femto Amperes. This value in my eyes (i am not so expertized like you in Spice Simulation) seems to be very small for a transistor with Ic=3A. For example, similar NPN transistors like BD137 with Ic=1.5A has IS = 48.15 femto Amperes. And the complementary PNP MJE172 has IS = 53.76 femto Amperes.
Can you help me please?
Thanks
Fotios
In all Spice models of MJE182 that i have download from On Semi site (PSpice, Saber, Spice2, Spice3) its parameter "Saturation Current" is given as "IS = 1e-17". When i put this value in the corresponding box of parameter table of the EDSpice Simulator that i use, is translated automatically (and correctly) in IS = 0.01 femto Amperes. This value in my eyes (i am not so expertized like you in Spice Simulation) seems to be very small for a transistor with Ic=3A. For example, similar NPN transistors like BD137 with Ic=1.5A has IS = 48.15 femto Amperes. And the complementary PNP MJE172 has IS = 53.76 femto Amperes.
Can you help me please?
Thanks
Fotios
For those who can figure out how to use it, SpiceMod can be downloaded here:
Steve Ekblad's Free Audio Software and On-Line Enclosure Design
Found it by accident on Google.
Many models available from the popular vendor sites sport a SpiceMod header, but I'm guessing the models are all made in batches and so an incorrectly used or configured SpiceMod spits out almost entirely wrong models. Most models in my experience don't give the device any justice and, stranger, I've seen the exact same models used for parts that are not alike at all.
- keantoken
Steve Ekblad's Free Audio Software and On-Line Enclosure Design
Found it by accident on Google.
Many models available from the popular vendor sites sport a SpiceMod header, but I'm guessing the models are all made in batches and so an incorrectly used or configured SpiceMod spits out almost entirely wrong models. Most models in my experience don't give the device any justice and, stranger, I've seen the exact same models used for parts that are not alike at all.
- keantoken
Last edited:
On the conversation about transistor testing:
With some work, I'm sure we could come up with a circuit designed to keep a transistor at constant dissipation/temperature while ramping up whichever parameters we're testing.
So say we want to extract an Hfe vs. Ic curve for a given device. We want to keep the device at a constant temperature so we decide to keep the dissipation at a steady 10W. Vce for the test will be 10V.
Average Ic for this would be 1A. So if we send the test current in pulses, with a duty cycle varying so as to keep an average of 1A, we will keep an average dissipation of 10W. The higher the frequency the better.
Duty cycle=Iavg/Itest
Are there any outstanding issues with this approach? The device should probably be left for a warm up period so temperature can stabilize.
- keantoken
With some work, I'm sure we could come up with a circuit designed to keep a transistor at constant dissipation/temperature while ramping up whichever parameters we're testing.
So say we want to extract an Hfe vs. Ic curve for a given device. We want to keep the device at a constant temperature so we decide to keep the dissipation at a steady 10W. Vce for the test will be 10V.
Average Ic for this would be 1A. So if we send the test current in pulses, with a duty cycle varying so as to keep an average of 1A, we will keep an average dissipation of 10W. The higher the frequency the better.
Duty cycle=Iavg/Itest
Are there any outstanding issues with this approach? The device should probably be left for a warm up period so temperature can stabilize.
- keantoken
actually not so difficult as it seems. using voltage controlled current sources and some stepped voltage sources, a curve tracer is a piece of cake. temperature control can be done with a large heat sink in a water bath (nor a perfect solution, but it would work better than a free standing transistor). temperature sensing can be done from the device Vbe. if the initial Vbe at 25C is known for a device, then the die temp for that device can be calculated from the Vbe following the -2.2mV/C characteristic of silicon. if the tracer were a PC controlled device, the Vbe could be sensed as part of the programmed tracing routine during an idle state between traces. the voltage/current data could be fed to a set of ADC,s and the curve data digitized, simplifying the modeling process. the software would be more difficult to make than the hardware. even without all of the data acquisition hardware, a simple curve tracer can be made with current sources, stepped voltage sources and an oscope. somewhere in my "archives" i have the schematic for one using CMOS counters for the stepped voltage sources that control the current sources.
LME49710 model
This model is intended for dual versions of above series of op-amps.
For single versions, like the LME49710, the supply current is way too high: 10mA, instead of 4.8mA (typically).
Regrettably, NS didn't publish a model for the latter, but one can easily modify the LME49860 model in order to get the correct supply currents. Go to the 93rd line and replace the current source "I9 8 4 5.8E-3" by "I9 8 4 0.66E-3". See also pic below.
Cheers,
E.
This model is intended for dual versions of above series of op-amps.
For single versions, like the LME49710, the supply current is way too high: 10mA, instead of 4.8mA (typically).
Regrettably, NS didn't publish a model for the latter, but one can easily modify the LME49860 model in order to get the correct supply currents. Go to the 93rd line and replace the current source "I9 8 4 5.8E-3" by "I9 8 4 0.66E-3". See also pic below.
Cheers,
E.
Attachments
Simulation Problems
I'm trying to simulate a very simple power amp and am getting bogus results. I've got the actual circuit working, but when I plug in the values I used, the output is driven to the negative rail.
I've tried this with Falstad's circuit simulator and SIMetrix with similar results.
I've checked and checked my schematic capture and it is like the amp I built. Unfortunately, the simulator thinks the circuit doesn't work.
It's my first time with a simulator and need some help. The Falstad circuit simulator is quick, easy and very cool. But the output is suspect. Because I get similar results with two simulators, I'm thinking it might be me.
Is this the right thread to ask for help?
I'm trying to simulate a very simple power amp and am getting bogus results. I've got the actual circuit working, but when I plug in the values I used, the output is driven to the negative rail.
I've tried this with Falstad's circuit simulator and SIMetrix with similar results.
I've checked and checked my schematic capture and it is like the amp I built. Unfortunately, the simulator thinks the circuit doesn't work.
It's my first time with a simulator and need some help. The Falstad circuit simulator is quick, easy and very cool. But the output is suspect. Because I get similar results with two simulators, I'm thinking it might be me.
Is this the right thread to ask for help?
Circuit
Thanks for your offer to help. Here is the picture:
The following is the net list exported from the Falstad simulator. You can run the Java applet at falsted.com. To import you would just paste the following into the import window in Falsted.
Thanks for your offer to help. Here is the picture:
The following is the net list exported from the Falstad simulator. You can run the Java applet at falsted.com. To import you would just paste the following into the import window in Falsted.
Code:
$ 0 4.9999999999999996E-6 10.634267539816555 43 2.0 50
t 1008 224 1040 224 0 1 -47.86079739748146 0.8552854219172727 100.0
t 512 480 544 480 0 1 -52.69926583344467 -0.253812085630301 100.0
t 864 192 896 192 0 1 -47.12089238070345 0.7399050167780139 100.0
t 1008 528 1040 528 0 -1 0.9955962439225914 -0.8571644056443688 100.0
t 864 560 896 560 0 -1 0.2538120759022249 -0.7417841680203665 100.0
t 272 304 304 304 0 -1 50.50652531151723 8.352876252693331 100.0
t 368 304 336 304 0 -1 41.553834077834395 -0.5998149712614245 100.0
r 1040 304 1040 352 0 0.33
r 1040 432 1040 384 0 0.33
r 976 272 1024 272 0 150000.0
r 976 480 1024 480 0 150000.0
r 528 176 480 176 0 3300.0
r 448 176 400 176 0 3300.0
r 336 192 336 240 0 22000.0
r 304 544 304 608 0 1600.0
r 256 320 256 384 0 22000.0
r 384 320 384 368 0 470.0
r 400 304 464 304 0 22000.0
r 544 512 544 576 0 33.0
r 128 304 176 304 0 2200.0
c 208 304 240 304 0 1.0E-5 -0.05888382426463867
c 192 320 192 368 0 1.0E-10 0.4476414775245122
c 464 208 464 272 0 1.0E-5 48.94284784685432
g 256 464 256 480 0
g 1120 432 1120 480 0
r 1120 384 1120 432 0 4.0
R 1040 608 1040 640 0 0 40.0 -50.0 0.0 0.0 0.5
R 1040 144 1040 112 0 0 40.0 50.0 0.0 0.0 0.5
g 384 432 384 448 0
w 112 304 128 304 0
w 192 368 192 384 0
w 192 384 256 384 0
w 256 384 256 464 0
c 384 384 384 416 0 9.999999999999999E-5 -8.158090260387986
w 384 320 384 304 0
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v 112 304 112 464 0 1 100.0 1.0 0.0 0.0 0.5
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w 896 144 1040 144 0
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w 1040 608 896 608 0
w 176 304 192 304 0
w 192 304 192 320 0
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w 256 304 272 304 0
w 304 256 336 256 0
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w 448 176 464 176 0
w 464 176 464 208 0
w 464 176 480 176 0
o 69 64 0 35 80.0 12.8 0 -1
o 57 64 0 35 80.0 9.765625E-5 1 -1It looks like the schematic is drawn wrong. You circuit is a jumble of at least 3 different topologies in a way that can't possibly work. Why don't you post your inspiration for the circuit, or find a proven schematic online to work with?
LTSpice is what I use, and it has an Education folder with a simple power amp example.
- keantoken
LTSpice is what I use, and it has an Education folder with a simple power amp example.
- keantoken
Original Inspiration
Here is the original inspiration...
Here's another one very much like it...
In my schematic, I simply made the TIP142/147 darlingtons into discrete pairs. That was after I tried single transistors with very high hfe. That didn't work either.
Yeah, I might have drawn the schematic wrong, but I can't find the error.
I'll try LTSpice again. I installed it but stopped working with it because I don't get the user interface. I entered the schematic, but can't figure out how to get steady state plots in Volts for a transient analysis.
Here's my LTSpice schematic. This is just a text file saved from the original ASC file. If you save it as an .asc file, LTSpice will open it.
View attachment SOCheap150.txt
Here is the original inspiration...
Here's another one very much like it...
In my schematic, I simply made the TIP142/147 darlingtons into discrete pairs. That was after I tried single transistors with very high hfe. That didn't work either.
Yeah, I might have drawn the schematic wrong, but I can't find the error.
I'll try LTSpice again. I installed it but stopped working with it because I don't get the user interface. I entered the schematic, but can't figure out how to get steady state plots in Volts for a transient analysis.
Here's my LTSpice schematic. This is just a text file saved from the original ASC file. If you save it as an .asc file, LTSpice will open it.
View attachment SOCheap150.txt
I found one small problem in the Falstad circuit. It's the 10uF cap between base and emitter of the driver. It should be a 100pF between base and collector. It doesn't make much difference in the simulation. Here's the corrected circuit:
Code:
$ 0 4.9999999999999996E-6 10.634267539816555 43 2.0 50
t 1008 208 1040 208 0 1 -48.73317764062409 0.8548069035323701 100.0
t 512 464 544 464 0 1 -51.00419236198607 -0.24972226768478123 100.0
t 864 176 896 176 0 1 -47.99375118686806 0.7394264537560336 100.0
t 1008 512 1040 512 0 -1 0.9911076442171307 -0.8567554972692548 100.0
t 864 544 896 544 0 -1 0.24973241999998663 -0.7413752242171441 100.0
t 272 288 304 288 0 -1 57.6209433924192 12.992524366523424 100.0
t 368 288 336 288 0 -1 44.02970730879695 -0.5987218694140273 100.0
r 1040 288 1040 336 0 0.33
r 1040 416 1040 368 0 0.33
r 976 256 1024 256 0 150000.0
r 976 464 1024 464 0 150000.0
r 528 160 480 160 0 3300.0
r 448 160 400 160 0 3300.0
r 336 176 336 224 0 22000.0
r 304 528 304 592 0 1600.0
r 256 304 256 368 0 22000.0
r 384 304 384 352 0 470.0
r 400 288 464 288 0 22000.0
r 544 496 544 560 0 33.0
r 128 288 176 288 0 2200.0
c 208 288 240 288 0 1.0E-5 -0.20227512325988162
c 192 304 192 352 0 1.0E-10 7.418678421474524
c 464 192 464 256 0 1.0E-5 48.04869136644873
g 256 448 256 464 0
g 1120 416 1120 464 0
r 1120 368 1120 416 0 4.0
R 1040 592 1040 624 0 0 40.0 -50.0 0.0 0.0 0.5
R 1040 128 1040 96 0 0 40.0 50.0 0.0 0.0 0.5
g 384 416 384 432 0
w 112 288 128 288 0
w 192 352 192 368 0
w 192 368 256 368 0
w 256 368 256 448 0
c 384 368 384 400 0 9.999999999999999E-5 -5.619807378713874
w 384 304 384 288 0
w 384 288 400 288 0
w 368 288 384 288 0
w 384 352 384 368 0
w 384 400 384 416 0
w 336 304 336 592 0
w 336 592 304 592 0
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w 304 272 304 240 0
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o 63 64 0 35 80.0 12.8 0 -1