Bought some fakes today! They even say Toshiba on them!
Measured?compared to some known good ones. Yikes!!!! Vceo should be 230V and up.
These bastards measured a mere 130V!!!
How do I tell the shop that sold them to me they're no good?
I don't usually buy them locally, but took a chance cos they had 'Toshiba' on them.
Are there ant tell-tale signs of knowing when Transistors such as these are fake???
Measured?compared to some known good ones. Yikes!!!! Vceo should be 230V and up.
These bastards measured a mere 130V!!!
How do I tell the shop that sold them to me they're no good?
I don't usually buy them locally, but took a chance cos they had 'Toshiba' on them.
Are there ant tell-tale signs of knowing when Transistors such as these are fake???
Hi. "How do i tell the shop that sold them to me they are no good"
I guess much the same as when you asked the shop for them. Just change sentence to .. These transistors are no good and are fakes and if you dont give me my money back im going to tell the diyaudio forum the name of your shop..
I guess much the same as when you asked the shop for them. Just change sentence to .. These transistors are no good and are fakes and if you dont give me my money back im going to tell the diyaudio forum the name of your shop..
NOS double crown TDA1541 from China? sounds like tell tale enough to me.Are there ant tell-tale signs of knowing when llTransistors such as these are fake???
I'd love to know the answer to that but there can't be any reliable signs as the fakers can always "improve" the faking process.
fakes will spread more and more and the only solution will be to buy from safe sources. I can only hope Farnell, RS and the like will not be touched by the disease.
It doesn't "allow" for 50mA!
50mA has to be forced, with an inductive load (usually) and the VCE0 measured. Has to be done with a short pulse or one dead transistor - see SOA curve.
Vce0 is the CE voltage with 0 (zero) current.
Surely all we need is a very high voltage supply and a high value resistor in series.
But, who likes playing around with ~300Vdc to 400Vdc for a test jig?
Would a pair of 39k 600mW resistors do the job @ 400Vdc?
When the current rises to or above ~2mA, then you have passed the Vce0
Surely all we need is a very high voltage supply and a high value resistor in series.
But, who likes playing around with ~300Vdc to 400Vdc for a test jig?
Would a pair of 39k 600mW resistors do the job @ 400Vdc?
When the current rises to or above ~2mA, then you have passed the Vce0
No, the "0" refers to what the base is doing, in this case open.
This breakdown test at a high current ("normal" reverse breakdown is usually at 10uA forced) is a special case for power transistors more accurately known as VCE(sus), the sustaining voltage.
This happens with an inductive load when the device is turned off (base open or reversed biased). The collector will fly up and break down the CE and the inductance will sustain whatever current was in the collector at switch off.
A bit off topic this, but VCE0 at realistic currents is not easy (or safe!) to do without special testers. It requires short pulses with low duty cycle to limit the power dissipation
look at the first test parameter and note the warning!
This breakdown test at a high current ("normal" reverse breakdown is usually at 10uA forced) is a special case for power transistors more accurately known as VCE(sus), the sustaining voltage.
This happens with an inductive load when the device is turned off (base open or reversed biased). The collector will fly up and break down the CE and the inductance will sustain whatever current was in the collector at switch off.
A bit off topic this, but VCE0 at realistic currents is not easy (or safe!) to do without special testers. It requires short pulses with low duty cycle to limit the power dissipation
look at the first test parameter and note the warning!
You may well be correct! I, too, am interested to see how those results were obtained.
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