200W MOSFET CFA amp

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M

mexmike

Member
Joined 2018
dadod said:
Here is the last 200W-CFA-VMOSFET zip file with .asc and models files.
Damir
Click to expand...

Hi Damir,

I may be wrong but I believe there is an error in this asc from your post #775 200W MOSFET CFA amp. C33 which goes between the two 15v rails, appears to shorted to the + input of the LT1022.

I had connected the cap like this in the modded version of the 100W CFA and could not adjust the DC offset after much poking around I realised what the problem was.

When I ran the sim with the input shorted and load open to check the bias and offset, I got -847.7544mV DC offset. Removing the short as per your 100W CFA attached allowed me to make/ test the adjustment.

As I say I may be wrong and will defer to your knowledge.
 

Attachments

  • Shorted Cap at Servo.JPG
    Shorted Cap at Servo.JPG
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  • Shorted Cap at Servo Sch.JPG
    Shorted Cap at Servo Sch.JPG
    187.3 KB · Views: 1,117
  • Not Shorted Cap at Servo.JPG
    Not Shorted Cap at Servo.JPG
    51.9 KB · Views: 1,156
  • 100 CFA- CM-VMOSFET-dado-1 Low PPM-sch.jpg
    100 CFA- CM-VMOSFET-dado-1 Low PPM-sch.jpg
    208.7 KB · Views: 1,156
  • 200W-VMOSFET-efVAS-mc-RC-150-0_47u-OIC-DCservo- VDMOS ksubthres models-Vbe_blue.asc
    24 KB · Views: 277
Last edited:
dadod

dadod

Member
Joined 2006
I would like to offer gerbers for my 100W CFA and corresponding Power Supply.
I hope more people will build this amp.;)
 

Attachments

  • 100W-CFA-VMOSFET-1.4-sch.jpg
    100W-CFA-VMOSFET-1.4-sch.jpg
    224.7 KB · Views: 816
  • BOM 100W CFA MOSFET rev 1.4.txt
    2.1 KB · Views: 292
  • 100W CFA 1-1.4 gerbers.zip
    180.9 KB · Views: 300
  • PS regulator BJT rev_1.4.sch.jpg
    PS regulator BJT rev_1.4.sch.jpg
    231.7 KB · Views: 672
  • BOM PS Regulator BJT-1.4.txt
    1.7 KB · Views: 239
  • PSR gerbers-ds-1_4.zip
    52.7 KB · Views: 259
C

craydive

Member
Joined 2011
Hi Damir,
The 100W circuit uses BC550 and BC560 transistors. The BC560 is not easily available/obsolete now.
Looking at the specs, would the use of BC549 and BC559 be ok. The BC549/BC559 has a Vceo = 30V, as compared to the BC560 Vceo = 45V.
I notice there is a 15V zener diode limiting the rail voltage where the BC550/BC560 transisors are used.
My thinking the BC549/BC559 pairing should be ok in the transistor positions of Q15/Q17, Q11/Q12, Q16/Q19 and Q3/Q4.
This would allow the use of the lower noise BC549/BC559 transistors, similar to the BC550/BC560.
kind regards
steve
 
Last edited:
asuslover

asuslover

Member
Joined 2016
craydive said:
Hi Damir,
The 100W circuit uses BC550 and BC560 transistors. The BC560 is not easily available/obsolete now.
Looking at the specs, would the use of BC549 and BC559 be ok. The BC549/BC559 has a Vceo = 30V, as compared to the BC560 Vceo = 45V.
I notice there is a 15V zener diode limiting the rail voltage where the BC550/BC560 transisors are used.
My thinking the BC549/BC559 pairing should be ok in the transistor positions of Q15/Q17, Q11/Q12, Q16/Q19 and Q3/Q4.
This would allow the use of the lower noise BC549/BC559 transistors, similar to the BC550/BC560.
kind regards
steve
Click to expand...
I have a bunch of bc550/560bta transistors.
https://www.diyaudio.com/community/threads/some-components-for-sale.314633/
 
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