Megatron Electrostatic Headphone Amplifier

[Shawn]

10 hours ago, JoaMat said:

Nice idea. If you can implement an auto detect function as well – like Elekit has done with TU-8900. 

Power module…

It's a great idea. I’ll likely move forward with the current plan for now since I’ve already ordered the PCB prototypes, but I definitely want to explore how that auto-detect function works.

My guess is that it detects the difference in cold filament resistance between 2A3 and 300B tubes, but I’m not exactly sure how it’s implemented in detail. I’ll need to dig into that more.

Also, from the image you shared, you reminded me that I should probably add a few small ceramic caps for filtering (like C9, C8, C7 on the right side of U1). Thanks for the heads-up.😅

The test PCBs should arrive this weekend. If I’m able to populate and test them successfully, I’ll report back with results.

BTW, do you know what kind of DC-DC chip on the picture? Too blurry for me to read.

[JoaMat]

I don't what chip it is. 

Marking might be???? Very hard to see.
26QH
288
A3HL

Including in curcuit is also dual comparator 2093B and  .05R sense resistor.

Good luck and looking forward a report.

[Shawn]

11 minutes ago, JoaMat said:

26QH
288
A3HL

Find it. I will share the info here anyway if you are curious. The switching freq range is between 900 to 2400(kHz). Lower than the LMQ, but shouldn't have any problems.

https://www.ti.com/product/TPS62913

[JoaMat]

That was fast! Thanks a lot.