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Transistor as a switch

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Been awhile. I thot hFE was ac gain and beta was DC gain. Not so?

Not that there is WW police watching any of this, I always thought HFE is DC,. hfe is AC.
But who is going to police US other than US ....and is hFE a trans transistor.....a little
bit of both.....

Regards, Dana.
 
Not that there is WW police watching any of this, I always thought HFE is DC,. hfe is AC.
But who is going to police US other than US ....and is hFE a trans transistor.....a little
bit of both.....

Regards, Dana.
The reason I consider beta dc is because of test set up that gives graphic representation of beta lines. And I spose a wantingness that hF = high frequency. I have no empirical evidence on hand though.BETA CURVES 1.1.png
 
Truth is, I've always studiously avoided the '3055 in any application involving more than ~1A of collector current. Much higher than that and its beta goes to pot even before its saturation voltages do. For higher currents there are better choices and have been for decades.
Righto, but I could get 100 - 3055s for $40. Hurts less when they go to smoke.
 
I'll guess because the cascaded pair of transistors configuration was designed before the term Integrated Circuit was coined.

The 2N3055 is a silicon NPN power transistor intended for general purpose applications. It was introduced in the early 1960s by RCA using a hometaxial power transistor process, transitioned to an epitaxial base in the mid-1970s

https://en.wikipedia.org/wiki/2N3055#:~:text=The 2N3055 is a silicon,transistor type of enduring popularity.

Robert Noyce invented the first monolithic integrated circuit chip at Fairchild Semiconductor in 1959.

https://en.wikipedia.org/wiki/Invention_of_the_integrated_circuit#:~:text=Robert Noyce invented the first,Atalla's surface passivation process.
 
Doesn't that kind of depend on what they take with them when they go?
Used almost exclusively in prototyping around my shed merely to prove theory of operation of untested circuits. If it works using a 3055, it will work with a rock with some wire wrapped around it. It did take more than the destruction of one unit to clue me in that trying to operate at nearly absolute maximum values is a not good practice.
 
Hello,

Here is an example of the MJ1000 darlington:
View attachment 55100
Bertus
I going to suggest that a darlington transistor will more resemble this device. This piece they said is counterfeit but its physical layout more matches my mental concept of a darlington. The way this device appears to be wired, it looks like two transistors in parallel.
TRANSISTOR DARLINGTON  COUNTERFIET 1.1.png
 
But it does. Have a close look at the structure:
View attachment 55145
I wondered about that but couldn't draw it out into a mental image that seemed workable. Also the few I have observed had two individual dies of equal (nearly) size. I'm still a little hazy on the interconnects. The base lead (let's say Q1) attaches to small pad which is surrounded by emitter of Q1, so that's one junction, then it looks like a single trace connects somewhere to the base of Q2 which I will guess is colored red and contacts the fingers of the emitter of Q2 forming another PN junction. Both collector regions are attached to the can and Bob's your uncle. It only makes sense that the mechanical structure has gone thru many design changes searching for better performance and maybe a savings in silicon. I'll give you that one. I just couldn't trace out the individual connection points. It's been a while since Barney, Fred, or myself have chopped open an enclosure to get to the bedrock. Might as well glue the top back on that one. :~)
 
The 2N3055 is a silicon NPN power transistor intended for general purpose applications. It was introduced in the early 1960s by RCA using a hometaxial power transistor process, transitioned to an epitaxial base in the mid-1970s

https://en.wikipedia.org/wiki/2N3055#:~:text=The 2N3055 is a silicon,transistor type of enduring popularity.

Robert Noyce invented the first monolithic integrated circuit chip at Fairchild Semiconductor in 1959.

https://en.wikipedia.org/wiki/Invention_of_the_integrated_circuit#:~:text=Robert Noyce invented the first,Atalla's surface passivation process.
According to Wikipedia, Sydney Darlington devised the Darlington pair transistor configuration in 1953.
 
According to Wikipedia, Sydney Darlington devised the Darlington pair transistor configuration in 1953.

Excellent. Now, if you'll be so kind as to scan down to "Packaging" in that same Wiki article, you'll find...

Packaging
"Darlington pairs are available as integrated packages..."
 
Bottom line - Bell's lawyers screwed up.

In the original 1953 patent there are 10 claims. The word "pair" appears a total of ten times in four of the claims. Nowhere does it say something like "two or more". If it had, Bell would have had the first patent for an "integrated circuit" six *years* ahead of TI.

OK, it's never as simple as that. Sidney's parts did not have electrical isolation between individual transistor elements, so it was more of a 5-layer device rather than individual transistors connected together in a circuit. Still, Bell would have had something to use in a court challenge. Given their size relative to just about everybody, let alone an oil well instrument company, it would have been quite a fight.

https://patents.google.com/patent/US2663806

ak
 
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