Greatest circuit ever (or weirdest)

[kenpeter]

As usual, I use it in an opto-compressor. 🙂

Opto-whatsit? Is that like a photodiode what watches
the plates turning red, and slighty dials back the bias?

 

[Wavebourn]

Opto-whatsit? Is that like a photodiode what watches
the plates turning red, and slighty dials back the bias?

Can you imagine an input attenuator controlled by peaks of grid currents?

 

[ErikdeBest]

Hi Anatoly (if I am not mistaken, there must also be an 'i' somewhere in there, but I don't know where...)

Thanks for the explanation! About 170V... My first thought was a rectified and filtered (with a source follower) insulation transformer, but on second thought it would be 'hard' to get 170VDC out of 120VAC. So I don't know... or maybe actual output voltage in the US is closer to 130VAC, which would allow for about 170VDC.

Erik

I see that you also ask about the garter bias. I think Michael is referring to this.

 

[Wavebourn]

Hi Anatoly (if I am not mistaken, there must also be an 'i' somewhere in there, but I don't know where...)

Thanks for the explanation! About 170V... My first thought was a rectified and filtered (with a source follower) insulation transformer, but on second thought it would be 'hard' to get 170VDC out of 120VAC. So I don't know... or maybe actual output voltage in the US is closer to 130VAC, which would allow for about 170VDC.

Isolation transformers give a nominal voltage under a specified load. Actually, they show 10% more.

Now, do you already know what to make an output tranny from? 😉

 

[ErikdeBest]

Most certainly another mains transformer. I did some calculations, but don't know if they are right:

Thinking about it I would say that the maximum peak to peak voltage on the primary can be 340V. This occurs when one plate is at double B+, consequently the other should be at 0V (??). That is about 120V RMS. On the load side: to get 300W into 8R one needs about 50V RMS (50V*50V/8R)... so the ratio primary secondary is about 2.4, and the impedance ratio is 6... the primary impedance would than be ~50 ohms???

 

[Wavebourn]

Yes, it would be about 50 Ohm.

I am going to build a stereo Barracuda prototype on a chassis soon. SY saw it breadboarded, but that time I used LEDs instead of an upper resistor in cathode. Almost no difference, except the radiation frequency. 😉