Peak to peak Detector, 1972 US Patent - for GR meter

[richiyobs]

Hi Folks,
found this old patent, can this approach be used for GainReduction metering?
From simulation it seems fine..... i still own 3 x PM2 100uA meter, the zero position is on left side... so I changed the arrangement of the BJTs, hoping to get the right needle movement.
i'm prototyping a new Jfet comp based on Vishay VCR app notes, very similar to API525C, so i'd like to use this solution for GR.



Thanks for your attention and for any advice and support

Best

 

[richiyobs]

from patent:
Accuracy of the peak-to-peak detector depends only on good saturation of the transistors and on low transistor leakage during cut-off. Emitter base junction breakdown may limit the output voltage capability, but a diode connected in series with each base and additional base-to-emitter resistors would eliminate this problem with no performance loss.

so how can calculate base-to-emitter resistors for this purpose?

 

[JohnRoberts]

Gain reduction metering is not trivial because gain cells are not very linear or well behaved. Modern VCAs are better in that regard for following gain laws.

JR

 

[richiyobs]

the meter is just ballistics... i don't need perfection, it's just for monitoring the constant timing... I like to have fun with electronics and learn old things... I know that modern VCA are Better in everything.
Is the proposed schematic good for my application?

 

[JohnRoberts]

the meter is just ballistics... i don't need perfection, it's just for monitoring the constant timing... I like to have fun with electronics and learn old things... I know that modern VCA are Better in everything.
Is the proposed schematic good for my application?

Gain reduction metering is not trivial because typical gain cells are not very linear

JR