TV Prisma 91 - Belgian 625/819 automatic hybrid

[LENINGRAD T2]

I think the topic of cable TV is interesting and worth pursuing in a separate post. Meanwhile, my patience was rewarded and I received extensive TV Prisma documentation. I need to translate it. Electrical solutions are certainly not common.

[LENINGRAD T2]

Here's what the invention of Belgian engineers from the Prisma factory looked like:

1. impulses from the separator /B9-ECC82/ reach the valve grid B8b-PCL82
2a. pulses of 625 lines / 15625 Hz / resonate with the VW3 circuit. A large negative voltage through D9 reaches the B20a-ECC81 grid. The anode current decreases in it.
2b. pulses of 819 lines /20475 Hz/ or no signal via B8b-PCL82, D9 increase anode current in B20a-ECC81
3. The anode current affects the position of the RL4 relay. The relay regulates the operation of the multivibrator /B19-ECC82/ and its frequency - two positions.

       

This idea was patented /1956/.