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Damn, even condoms were cooler in the past. https://www.rijksmuseum.nl/en/press/press-releases/rijksmuseum-exhibits-200-year-old-condom-featuring-erotic-print

This post is a bit long, but if you're interested in alternative filament supply ideas for DHTs, feel free to read on. I know @kevin gilmorehas already mentioned and implemented a solid filament supply solution for 300B tubes using five modular switch-mode power supplies from Traco. One 12V unit is used for controlling soft start, and the others supply 5V for the 300B filaments. It’s a good and proven design. However, I believe it may take up more space than I can afford in my chassis, so I’ve been working on an alternative. Summary of My Design Concept: 1. Inspired by @JoaMat approach using rectification + DC-DC regulation, aiming for a similar or smaller footprint. 2. Native soft-start behavior with no need for external resistors to set ramp-up current or output voltage. 3.Up to 5V @ 3A output per module. 4. Molded inductors for reduced EMI 5. Adjustable switching frequency (to avoid audio band). 6. Dual-random spectrum modulation for further EMI suppression. 7. No heatsink required. I’m currently working on the PCB layout based on my schematic (slow progress – I’m not a professional). Any suggestions, corrections, or feedback would be greatly appreciated! 1.Design Rationale (skip if you’re only interested in the result): There are many DC-DC converter chips available, but my criteria were: Very small footprint Adjustable switching frequency (to avoid 20Hz–20kHz band) Integrated soft-start, over-voltage, and over-current protection (to safeguard DHT filaments) Output current ≥2A @ 5V Low noise and ripple Adjustable output voltage (to support both 2.5V for 2A3 and 5V for 300B) After some research, I settled on the TI LMQ664x0 series, which offers 1A/2A/3A variants. To leave some headroom, I chose the LMQ66430, rated for up to 3A output and 36V input. Datasheet:https://www.ti.com/lit/ds/symlink/lmq66430.pdf This chip is extremely compact – only 2.6mm x 2.6mm – though I’m still unsure if I can hand-solder something that small.☹️ 2. Circuit Topology (text version for now): Although I’ve drawn a test schematic, the files are on another computer. I’ll post them later if needed. In general, the topology is quite typical: Use a transformer with a secondary in the 9–16V AC range, Rectify the output, Feed it to the LMQ66430 module. Key connection notes (based on the datasheet): PIN 1 and PIN 3: Rectified DC input PIN 6: GND PIN 7: Output through an inductor (preferably molded) PIN 8: NC PIN 10: 1μF to GND PIN 11: Feedback resistor network for setting Vout (see page 29) PIN 13: Set switching frequency (tie to GND for 2.2MHz; see page 14) PIN 14: NC PIN 15: GND For layout reference, check Page 39. Also, combinations and example circuits are shown in Page 9.2 Disclaimer: I haven’t verified every detail yet. In this way, there may be changes before I finalize the layout and perform live testing. I have some concerns if two modules can work in parallel. In Megatron XL, the two 300Bs per channel share the same filament supply. If I use two separate LMQ66430s in parallel, I’m unsure whether uneven current draw might become a problem, since these chips don’t have a master/slave current-sharing mechanism. I have another separate question, please bear with me for bringing this up here: If I substitute 300B with EML 20B-V4, I understand that I no longer need the pair of 3300Ω balance resistors and should instead use a cathode resistor connected to the center tap (CT) of the filament. But I’m unsure about how to treat the G-stage resistor R4 (680kΩ). Should it connect from the grid to the cathode, or from the grid to -450V? My guess is that the G-stage connects to -450V through the 680k, and the cathode bias is set independently via the CT, not the filament ends. I admit I’m not very confident when working with DHTs – I often get confused by how CT-based cathode bias works when combined with DC filament supplies. Any insight would be really appreciated!😊

50yo Wind On The Water by Crosby & Nash (1975) https://album.link/5vnkkwtcmj2vj Example: There were a couple albums of just the duo. Nice set of tunes.

ew... {begin rant} Well you were right. I didn't have the stomach to watch past a few minutes. As soon as I heard 'Physics Establishment' I knew that it was Crackpot time and I was done. I am sorry I gave it that much time, they probably got credit for a view. I at least was able to give it a thumbs down. There are several vids by Angela Collier about Crackpots - and they are scary people that are mad.... I like Sean Carroll - I read his pop physics books back in the day: From Eternity to Here: The Quest for the Ultimate Theory of Time The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime I would rather read papers than books aimed for public consumption now. But Sean is a well respected in the industry with over a hundred published research papers. He falls in the camp of Brian Greene for me as a science educator. In some ways I hate that he did this. It raises the status of 'people that yell' that their theory is worthy of debate. {end rant} Back to working on my theory of everything that they cannot handle....

RIP Jim Marshall, 87, the first of the Minnesota Vikings four defensive linemen known as the "Purple People Eaters" to pass away. Always thought it was a crime that he was never elected into the NFL Hall of Fame. Grew up as an avid Vikings fan in the 70s. By all accounts, he was a good man otherwise as well. Time sure flies.

Had quite a shock today. My Sister in law sent me a pic of my Mom on the day of her death. This is a picture of her Christmas before last... This was her the day she died... Just 1 1/2 years later. I was shocked!