5 V?To help you with this problem look again at my post #14 and Ask yourself -- >What voltage at the T1 base will cut-off T1 transistor?
5 V?To help you with this problem look again at my post #14 and Ask yourself -- >What voltage at the T1 base will cut-off T1 transistor?
I get R6 = 67 Ω and Ic4 = 0,309 AView attachment 103188
For this circuit to turn-ON the BJT the voltage at the base must be 0.7V larger then the voltage at emitter.
and for this circuit the emitter voltage is 10V * Re/(Re + RL) = 5V therefore Vb should be larger than 5.7V so to have transistor in active region of operation. Because for Vb lower than 5.7V BJT is cut-off.
In your amplifier we have a similarly situation. The emitter resistor and the load resistor form a voltage divider, so the output peak negative swing will be -21V* 49/(R6 + 49) = -8.8V and from there we can find R6 = 62Ω. And Ie4 = 21V/62Ω = 0.34A
62Ω is a standard resistor value from E24 series. Which means that you cannot buy a 67 ohm resistor.I get R6 = 67 Ω and Ic4 = 0,309 A
Yes, you need to know the gain formulaSo I have to find a correct gain formula for the first two stages?
I do not know. Look it up in google or in the book or do a small-signal analysis and derive gain expression yourself.How can I find the corresponding gain A1?
Ie is 1mA ? Why not 1.825mA ? And what about R1 and R2 ?ϒe is: VT / IE = 25 Ω
Av1= Rc / 2* ϒe = 2 / 2* 25 = 40.
Ie4 is 0.01A = 10mA ??ϒe4= VT/Ie4 = 0,025 / 0,01 = 2,5 Ω
Ri4= (β4+1) ( ϒe4+R6) = 401*(2,5Ω+62) = 25,86 KΩ
looks good.Av2 = (R5 II Ri4) / (ϒe3+R4)
Gain A1:Ie is 1mA ? Why not 1.825mA ? And what about R1 and R2 ?
Ie4 is 0.01A = 10mA ??
Now I'm happyRi4= (β4+1) (ϒe4+ (R6||RL) )
The two red ones? Yes, because its R6 parallel with RL
Start by finding a BJT with a hfe/β larger than 400 for Ic > 0.1A and Pd > 0.3A*21V = 6.3WSo what to do now?
Type Polarity Package Vceo Ic Hfe fT Power.
2N6294 NPN TO66 60 4 750-18k 4M 50
2N6295 NPN TO66 80 4 750-18k 4M 50
2N6297 PNP TO66 80 4 750-18k 4M 50
2N6298 PNP TO66 60 8 750-18k 4M 75
2N6299 PNP TO66 100 8 750-18k 4M 75
2N6300 NPN TO66 60 8 750-18k 4M 75
2N6301 NPN TO66 80 8 750-18k 4M 75
2N6312 PNP TO66 80 4 750-18k 4M 50
2N6394 NPN TO66 60 4 750-18k 4M 50
2N6395 NPN TO66 80 4 750-18k 4M 50
2N6534 NPN TO66 80 8 100-5k 20M 14
2N6535 NPN TO66 100 8 100-5k 20M 14
2N6536 NPN TO66 100 8 100-5k 20M 14
2N6537 NPN TO66 120 8 100-5k 20M 14
BDS20 NPN TO220M 80 5 1000min 8M 50
BDS21 PNP TO220M 80 5 1000min 8M 50
BDT63 NPN TO63 60 10 1kmin - 90
BDX62 PNP TO3 60 8 1kmin 7M 90
BDX62A PNP TO3 80 8 1kmin 7M 90
BDX62B PNP TO3 100 8 1kmin 7M 90
BDX62C PNP TO3 120 8 1kmin 7M 90
BDX63 NPN TO3 80 8 1kmin 7M 90
BDX63A NPN TO3 100 8 1kmin 7M 90
BDX63B NPN TO3 120 8 1kmin 7M 90
BDX63C NPN TO3 140 8 1kmin 7M 90
by Jake Hertz
by Jake Hertz
by Jake Hertz