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U6A and U6B are connected in parallel so that the output current is 2x.
R331 converts the outputs of UG(a,b) to a current.
So, about (15-0.6)/330 Amps flows into the base. That's 0.043 Amps
Hfe for a 2n2222 is probably around a 100. I didn't look it up.
The datasheet https://www.electro-tech-online.com/custompdfs/2013/04/CD00003223-83285.pdf suggests 40. I'll still use 100. The end result is still mostly the same except the 4.3 A gets reduced by 40/100. A little over a factor of 2.
The 43 mA get's multiplied by about 100, so about 4.3 A CAN flow through the collector.
Ir's still way bigger than the transistor can handle, so the transistor will saturate and be fully turned on.
The transistor still cannot handle more than it's 600 mA rating, so the rating and the load limit Ic.
Remember Ib+Ic=Ie and Ic=β*Ib and Ie=(β+1)Ib; β=Hfe.
U6A and U6B are connected in parallel so that the output current is 2x.
R331 converts the outputs of UG(a,b) to a current.
So, about (15-0.6)/330 Amps flows into the base. That's 0.043 Amps
Hfe for a 2n2222 is probably around a 100. I didn't look it up.
The datasheet https://www.electro-tech-online.com/custompdfs/2013/04/CD00003223-83285.pdf suggests 40. I'll still use 100. The end result is still mostly the same except the 4.3 A gets reduced by 40/100. A little over a factor of 2.
The 43 mA get's multiplied by about 100, so about 4.3 A CAN flow through the collector.
Ir's still way bigger than the transistor can handle, so the transistor will saturate and be fully turned on.
Hfe is AC current gain. HFE is DC current gain.
HFE is used when there is plenty of collector to emitter voltage so the transistor is not saturated.
The base current is 1/10th the collector current for a saturated small transistor and hFE is not used.
@audioguru
I never knew that distinction before. Thanks. At least I used the DC current gain.
@the OP
There is a major debate on what a transistor is.does or whatever even on this forum. So let;s just say that whatever current that is fed into the base,it's multiplied. Because the base current is multiplied, the transistor can function as an amplifier.
When all you see connected to an NPN transistor is ground to the emitter, Load from the collector to V+ and a base resistor, it's is functioning as a switch especially if the voltage on the other side of the resistor has two distinct states, like 0 and 5 V.
I just took a peek at a small jfet 174 and a common NPN transistor, the 2n3904. The J174 maxes out at 50 mA and the 2n3906 at about 200 mA. The NPN is about 3 cents (leads) and the J174 is about 12 cents SMT. Leads packages are gone).
With very high currents, FETS have a huge advantage (Rds(on)), but they are sometimes tough to drive.
So Transistors have more of a current output than a FET?
Need more current on the input to drive a FET, with a transistor u need low current on the base to turn it on , with a FET u need a lot of current to turn a FET on?
Need more current on the input to drive a FET, with a transistor u need low current on the base to turn it on , with a FET u need a lot of current to turn a FET on?
A FET uses NO current to turn it on. Its gate is insulated from its drain and source pins.
A Mosfet needs a fairly high momentary current on its gate to turn it on quickly and charge its fairly high gate-source capacitance. If it is turned on slowly then there is NO gate current.
A Mosfet can switch a current that is up to 5 times higher than a power transistor.
An ordinary transistor needs a base current that is 1/10th its collector current when it is a switch and the current is not too high.
These are 4500 A at 4500 V. They are not Biplolar Transistors, Nor FETS, but IGBT's.
The last three points I agree with. The first and the second points are dubious. Some truth in them though. Neither a bipolar transistor, nor a FET can switch 4500 V at 1200 Amps, but an IGBT can.
See, it depends on your definition of High current and High voltage, right?
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