75W BJT amplifier "Mona"

[mosfet54]

HI, i present you "Mona", it uses bd679/680 as output transistors.

They are 40W darlingtons -> Q1+Q4+R1+R3 simulate bd679.
same for the downer side.

I forgot a cap in the fb, for DC protection.

Greetings, any oppinions would be welcome.

 

[jacques antoine]

Q5 and Q8 collectors are dangling.
J.

 

[mosfet54]

R12 should be 4x10k in parallel. Here are Ac and fourier analys.
2nd fourier is this OPS with an op-amp.

 

[mosfet54]

Q5 and Q8 collectors are dangling.
J.

yes

i use their junctions as diodes as vbe, they are mounted on the heatsink.

 

[mosfet54]

I am wondering why i get 100% better results without current mirror

Look, harmonics here are 0.000...
only 6th is 5.43...

 

[Moderation Team]

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Thank you.

 

[Ketje]

I am happy to tell all of you that this circ has nothing to do with me.
Mona

 

[mosfet54]

i built the input stage on a breadboard and it not works, i am wondering is this from the breadboard's capacitance

ops is working perfect..

 

[ilimzn]

yes

i use their junctions as diodes as vbe, they are mounted on the heatsink.

Which still means collectors are dangling... because unlike simulated transistors, real ones have a limit to Ib.
But since you are into transmitting while talking to yourself, who cares.

 

[mosfet54]

yes and the current there its ok for their bases.

 

[mosfet54]

up

 

[mosfet54]

latest mona perfect result, missing 15-22k to ground @ input point

/!\ im pushing Q6 and Q7 to the limits, they are rated 65 volts and there are 57V max

 

[mosfet54]

oops c2 must be reversed !!

like here:

 

[mosfet54]

little update:

output transistors bdx53c/54c are suitable as bd679/680.

mj11032/33 are for simulation only (their beta is changed in the simulator).

distortion is less without input LPF

This time adjustable bias
from 4 to 114mA

 

[mosfet54]

look at my very good idea here ->>
simpler and drops distort very much

 

[mosfet54]

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