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Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

My Transistors, original or copy?
My Transistors, original or copy?
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Old 1st October 2017, 03:02 PM   #891
davidsrsb is offline davidsrsb  Malaysia
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The easiest way to separate real power transistors from a small die in a big case is to test at fairly high current and low Vce of no more than 3V. Achieving 50% of rated power for even a few seconds requires a very big heatsink. Getting 80% of rated power requires water cooling
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Old 1st October 2017, 03:14 PM   #892
thimios is offline thimios  Greece
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Quote:
Originally Posted by davidsrsb View Post
The easiest way to separate real power transistors from a small die in a big case is to test at fairly high current and low Vce of no more than 3V. Achieving 50% of rated power for even a few seconds requires a very big heatsink. Getting 80% of rated power requires water cooling
What's the problem with water cooling?
Distilled water is cheap.
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Old 1st October 2017, 03:42 PM   #893
woody is offline woody
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My Transistors, original or copy?
I bought a few Ld1014D jfets from Huayi- components on ebay. Turns out they were rebranded mosfets not the power jfets they were suposed to be. Now what to do with a rebranded part I hate to just throw them away ? Well lesson learned I should have bought
them from Deepsurplus they still have a few of these power jfets for a rather low price and
they test good!
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Old 1st October 2017, 05:36 PM   #894
anatech is offline anatech  Canada
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My Transistors, original or copy?
Hi woody,
Destroy them, then discard them. Otherwise they will crop up in a future project and cause you grief all over again. There seems to be something therapeutic in the act of destroying the fakes.

Hi Andrew,
Thank you.

-Chris
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Old 1st October 2017, 05:48 PM   #895
anatech is offline anatech  Canada
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My Transistors, original or copy?
Hi SMY14INCH,
Do you know what S.O.A. curves are? By using these curves, you can select an operating point that is within allowed ratings. To do otherwise is not telling you much of anything.

The 2N3055 was originally designed as a power supply pass transistor with a Vce of 60 VDC and a Ft (-3dB) of 19 KHz. Perfect for a pass device. Audio use came later as these were bottom of the barrel, cheap parts. Cheap but not good for audio.

When you are looking at the specs for a transistor, go by the Vcebo values. They are lower, but the correct one to use. For the 2N3055 I believe the values would be 100 V or 60 V. The 60 V value is what you use to create reliable circuits. One thing that has changed with the 2N3055 is the Ft point. It has been redesigned and so isn't the original part. They didn't change the number designation in any way and I have a huge problem with that.

Why not use power transistors that were designed for audio use? As long as the circuit is up to it, they will perform better.

-Chris
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Old 26th October 2017, 06:11 PM   #896
LiDer is offline LiDer  Russian Federation
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Just receive this from local store. All transistors looks different.
Click the image to open in full size.

Click the image to open in full size.
Photos made under different lighting conditions.
Is it fake or original?
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Old 27th October 2017, 09:13 AM   #897
AndrewT is offline AndrewT  Scotland
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certainly different production.
Does the datasheet dimension details help identify the genuine devices?

And please attach a cropped version, rather than use a remote server with automatic download.
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Old 27th October 2017, 03:07 PM   #898
LiDer is offline LiDer  Russian Federation
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Pins 2SC2837 is higher than 2SA1168 (the distance by datasheet from the heatsink should be equal to 1,7mm in both cases). Fourth in the upper row and 1, 2 in the lower row are more correspond with the size of the datasheet. The others do not match the width of the pins. Also strange marking of 2SA1186. The last letter corresponds to Hfe, but there are digits on this place. On the other hand, I bought it from a big local supplier. It's unlikely that it is selling fakes.
Crop photos:
IMG_9659.jpgIMG_9660.jpg
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Old 27th October 2017, 10:33 PM   #899
ej25awd is offline ej25awd  Canada
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Here's what I think about the package and mold. Compared to original Sanken parts that I have that are in TO-3P/MT-100 and MT-200 package, the collector lead near the body is wider than the base and emitter leads. The ones I didn't mark as fake appear to be the usual Sanken part. Now the question is are they not relabeled? The reason I'm bringing this up is that lettering appear to be inconsistent. If the surface is too shiny then, it was sanded off. Use acetone and see if the label comes off easily

Sanken datasheet is very specific on the lead dimensions, that alone is an easy way to weed out the obvious fake parts.

The next step is measure the Cob with 10VDC reverse voltage applied. Then run the part through a curve tracer.

DigiKey sells these parts. I trust them 100%. I also have a BIG local seller but they also sell fakes.
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Old 28th October 2017, 02:49 AM   #900
anatech is offline anatech  Canada
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My Transistors, original or copy?
Also, watch out for old device numbers with laser etched markings. If you see this, 99.999% chance the parts are not real.

-Chris
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