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Very simple quasi complimentary MOSFET amplifier
Very simple quasi complimentary MOSFET amplifier
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Old 17th September 2018, 08:19 AM   #2281
Bangla H is online now Bangla H  Germany
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Post VSQHA

Quote:
Yes, thanks Colin, that is the reference, #2246 on page 245. But note that schem indicates 32V rails, yours may be higher.
What you really need are the bias points for the output stage, and the reference voltage for the input transistor base, shown here at -1.95V.
My thanks to Bangla H!

Hello Hugh and Fellas.


I only have saved files to be sure for service my own failures, if possible.
If Thimios and Other don't helping with shared results of work, me (other?) staying lost in forest.

No reason to thank, Hugh- Thanks back for your help and attention.


As Ranchus thread started here i was following up to page 75 and save notices
in a Word DOC(X)-PDF.
I show it here, so any interested could use it for own need now.
Attached Files
File Type: pdf Very Simple Quasi Hybrid Amplifier.pdf (693.9 KB, 76 views)
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Old 17th September 2018, 08:37 AM   #2282
AKSA is offline AKSA  Australia
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Gee, Bangla, you have put my doodling into a pdf, Thanks and WOW!
I read through it again and actually found it a little confusing, but I could do better again if anyone asks me again!

HD
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Old 17th September 2018, 09:30 AM   #2283
thimios is offline thimios  Greece
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All my test is here in the thread post#346
I haven't test this pcb so i can't know if any bag.
Please use primary side protection, variac or lamp.
Use protective resistors in fuse position.
If you can't read resistor code use ohmmeter to be sure.
When chouse alternative parts be sure that is pin compatible or use the net for proper installation.
Again... schematic is bug free now but pcb is unknown to me.
Regards
Thimios.

Last edited by thimios; 17th September 2018 at 09:42 AM.
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Old 17th September 2018, 05:51 PM   #2284
Bangla H is online now Bangla H  Germany
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Talking doodling

yes Hugh ,but was most helpful here and there to come on right way.


As a ZERO- Expert i was puzzeling, a bit for me, some comments.


Very simple quasi complimentary MOSFET amplifier

Sorry Thimios, if it was not right to name you here.
Bandols Bord is a mix of Prasi and DACZ in unique size.
Your actually comments are right.
All work must be done in proper way.

I know you are more busy in Valery's & Jeff's Projects now.


Regards
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Old 18th September 2018, 02:07 PM   #2285
bandol83 is offline bandol83  France
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Hi,

I am building the second channel with the KSC1845 (instead of the 2N5551) that I should receive tomorrow from Mouser, and I have several question to be sure to avoid other mistake

1) On two schemes from DACZ REV 2 from AUG 22, it is indicated KSA1845 on one and KSC1845 on another, I think the KSC1845 the good one because the KSA1845 does not exist

2) For R19, I have only resistor in 0309 package or 120 ohm, can I use a 100 ohm like indicated another schema and as used by XRK because I have made the layout for 0207 resistor size ! I put a 100 ohm in the first channel in fact but since I had power level problem I am more careful now

3) I will use a 5.1 ohm resistor for R17 as it was confirmed that it should be OK and XRK used 10 ohm witout problem !

3) I will use FQA40N25 MOSFET and MJL3281AG bipolar to accept a dual 35 V 300 VA power supply transformer which may give up to 47 VDC after rectifier bridge, is it acceptable for this amplifier or should I use a 30 V version ?

Thanks for your help, I hope this second channel will play music soon and that I can repair the first one after...

Regards,
Marc
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Old 18th September 2018, 02:13 PM   #2286
thimios is offline thimios  Greece
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Quote:
Originally Posted by Bangla H View Post
yes Hugh ,but was most helpful here and there to come on right way.


As a ZERO- Expert i was puzzeling, a bit for me, some comments.


Very simple quasi complimentary MOSFET amplifier

Sorry Thimios, if it was not right to name you here.
Bandols Bord is a mix of Prasi and DACZ in unique size.
Your actually comments are right.
All work must be done in proper way.

I know you are more busy in Valery's & Jeff's Projects now.


Regards
Nothing wrong dear!
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Old Yesterday, 08:34 AM   #2287
bandol83 is offline bandol83  France
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Hi Hugh,

I have read in your post 1795 this : "There is switching taking here; the diode, the resistor, and quasi. This switching causes higher harmonics. When you measure the 120/150 combo, you get this at +20dB output, attached as Ranchu120-150.
When you measure the 150/150 combo, it's very similar here attached. I can actually see no reason to make these resistors, R19 and R14, different. They should be the same value; in this situation, I'd use 120R for both. In the FFTs, all quiescents were set to 125mA for correct comparison.


You suggest to use 120R for both R14 and R19, but can I use 150R or 100R with similar result (I still haven't 120R in 0207 package ) ?

Since I am waiting the KSC1845 from Mouser I read all the thread and I have found very interesting information

Best regards,
Marc
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Old Yesterday, 08:54 AM   #2288
AKSA is offline AKSA  Australia
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Yes, Marc, I would use 120R for both; the emitter resistor, and the collector on the inverter. You can also use 100R, it's probably a bit heavier for a lower beta on the output quasi.

Hugh
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Old Yesterday, 09:02 AM   #2289
bandol83 is offline bandol83  France
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Thanks Hugh
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