Help to convert these Lat-Fet amp to Toshhiba mosfet - diyAudio
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Old 29th January 2015, 11:38 AM   #1
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Default Help to convert these Lat-Fet amp to Toshhiba mosfet

Hi
I would like to get some help to convert these Lateral mosfet amplifier to Toshiba 2SK1529 & 2SJ200 (vertical type)
I do have at least +20 pair of that Toshiba mosfet. I built several Lat-fet amplifier I would love try out these circuit with those Toshiba devices.
At least close to these circuit with the req. mod.
I have the layout for these OS
Thanks for your help and advise
Greetings
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Old 29th January 2015, 04:43 PM   #2
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As far as I know there is not much difference in their caracteristics of the originals (SSK 1058-2SJ 162) and the Toshiba ones. Higher Id, higher Uds, more Pd, and slightly different trensfer caracteristics. And yes, different pin layout.
If you replace R70 (or R89) with a 1k trimpot you will be able to set Io with the Toshiba devices. Their Cgs capacitance is a bit higher too, but with the kind of drive on your schematic this should be no problem. Also the 470 ohm gate stoppers seem to be a bit much for those devices ,try 150-220 ohms instead.

Last edited by dragonweed; 29th January 2015 at 04:50 PM.
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Old 29th January 2015, 05:04 PM   #3
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Thank you very much
The main issue here one is lateral the other Toshiba is vertical mosfet
One has negative tempco the other opposite.
If I do not take care about that it will be thermal issue and probably other problems to.
I totally agree your advise just not sure that will take care all, that mode will do the trick.
Greetings Gabor
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Old 29th January 2015, 05:27 PM   #4
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You can use an active Vbe multiplier then in place of R70 and 89, with its transistor mounted to the FET-s heatsink for thermal compensation, as with a standard BJT output stage.
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Old 29th January 2015, 05:56 PM   #5
juma is offline juma  Germany
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Vgs multiplier would be even better...
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Old 29th January 2015, 05:57 PM   #6
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True!...... (just the power of habit.)
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Old 29th January 2015, 07:51 PM   #7
Bensen is offline Bensen  Belgium
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Vgs...I don't think so.
Check the attached PDF in this post. I did some trials with a 1530/201 output stage to achieve perfect thermal stability.




Amp design for subwoofer and wideband duty
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Old 30th January 2015, 12:52 AM   #8
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I made some of those change was advised.
Also I will have to ad some VBE into the red box.
Tomorrow I will work on it, right now just to sleepy, just slept 2 hours last night.
More advise always welcome

Greetings
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Old 30th January 2015, 01:36 AM   #9
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I use Vbe multiplier with transistor mounted up against the heat sink.
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Old 30th January 2015, 02:36 AM   #10
Art M is offline Art M  United States
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What is being Multiplied is the Base/ Emitter voltage of a BJT not the VGS of a FET ?
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