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PSU for Calvin buffer

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Rudi_Ratlos

Rudi_Ratlos

Member
Joined 2009
Frans: I have replaced the 1R - C-R-C - filter resistor by a 33R one (look at it - keeping in mind the voltage drop across it) and have connected the output to my Tektronix 465B.

I am not able to show you any variances on the output voltage!
The layout of this PSU seems to be quite o.k. then!

Best regards - Rudi
 

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FdW

FdW

Member
Joined 2009
AndrewT said:
The "shape" of the ripple waveforms should look VERY different on the two Cs of the CRC.
Have another look.

If you can't see any difference in the shape, then 33r is still too small !!!!
Click to expand...

Yes, it all depends on the current through R (and the voltage over as it is I * R). Also check Ft at '1 / (2 pi R C)' where C is the buffer capacitor, the -3db point should be considerably below 100Hz (I would say the 10 Hz is a nice target).
 
FdW

FdW

Member
Joined 2009
Rudi_Ratlos said:
Frans: I have replaced the 1R - C-R-C - filter resistor by a 33R one (look at it - keeping in mind the voltage drop across it) and have connected the output to my Tektronix 465B.

I am not able to show you any variances on the output voltage!
The layout of this PSU seems to be quite o.k. then!

Best regards - Rudi
Click to expand...

The point of this all is, by removing noise from the regulator input it (the regulator) will be able to do a better job. To see how this job is performed, you should load the regulator with a (as large as possible within the design limits of the PSU) dynamic load. Then you check the currents flowing in and out of the first and second capacitor (of the C R C) and there you will see large differences. Also you will see that the PSRR of the PSU has improved, the output/line regulation will only marginally improve (but there will be an improvement) and this is harder to spot (a FFT analyzer may be needed).
 
FdW

FdW

Member
Joined 2009
Rudi_Ratlos said:
Frans, I do not have the time to go on evaluating my PSU, since I am very (too) busy with a TO3/DX - SYMASYM edition, offered to German DIYers currently.
Will you please go on?
You will have the PCBs in a couple of days (have them already?).

Best regards - Rudi_Ratlos
Click to expand...

I will try to find some time for testing (but I was not planning on building the supply immediately, more like saving them for a later day).
 
Rudi_Ratlos

Rudi_Ratlos

Member
Joined 2009
Werner: give Frans some time, please! I am sure that he will evaluate my PCB very soon.

I am very unhappy that I cannot do this myself, but my workbench is crowded with plenty of TO3 - transistors (MJ21195G/MJ21196G) currently that need some matching due to a very special offer
of a "TO3/XD - SYMASYM" - version that I have offered to my German DIY-friends.

Best regards - Rudi_Ratlos
 
FdW

FdW

Member
Joined 2009
Rudi_Ratlos said:
Werner: give Frans some time, please! I am sure that he will evaluate my PCB very soon.

I am very unhappy that I cannot do this myself, but my workbench is crowded with plenty of TO3 - transistors (MJ21195G/MJ21196G) currently that need some matching due to a very special offer
of a "TO3/XD - SYMASYM" - version that I have offered to my German DIY-friends.

Best regards - Rudi_Ratlos
Click to expand...

:)
 
C

Catal

Member
Joined 2004
Calvin buffer as HP driver.

Hi Calvin,
what do you mean as "beefed up"?

I've got a couple remaning pcbs from Paradise phono pre and I'd like to try your buffer as HP driver.

As buffer in the phono pre it's Manifico!


Frank



Calvin said:
Hi,

Yes, it was intended as a standalone Buffer, or part of a preamplifier as You might see from its original thread.
It may be beefed up as a HP-driver or even as a low wattage power stage for loudspeakers.
As for the Q of how good it is, I think I may say ... satisfying. ;-)

jauu
Calvin
Click to expand...
 
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