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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

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.

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.

Took a Boat To The City Saw some controversial art. SF prices? Walked to a tech conference, where the zeitgeist is not just AI, but agentic AI. With phat/sick beats. And the expected A/V kit. Had a tech demo from a CEO, as one does. No need to be alarmed, citizen. Your timer starts now ... The conference ended with a nerd get together ( Code Block Party) Then some San Franciso Street Life And a First Thursday Gathering with one of many Waymos. Then back past the art, In time to catch the Last Ferry back a busy, but enjoyable day

Corporate Marketing Budget Depletion by eating in San Francisco today. There was quite the selection. But choose wisely! I think I did. But a reminder to always read the small print to avoid failure of expectations. A neighbor at my table thought they were getting a Bacon Cheeseburger, But instead got a "Bacon" Cheeseburger. Plant based Bacon sounds like an oxymoron, and was described as "an abomination". Avoid. However, later that day there were cheese truffle fries. Not bad. Where's the duck fat, though?

Or not. https://www.nytimes.com/2025/06/05/science/moon-landing-ispace-japan.html?unlocked_article_code=1.M08.WJzn.34xFxtsdzOad&smid=nytcore-ios-share&referringSource=articleShare (gift article)

Nice idea. If you can implement an auto detect function as well – like Elekit has done with TU-8900. Power module… filament supply in black square, and the tiny - 2mm x 2mm - step-down converter.

https://youtu.be/o4qbnQAsC-8?si=eobRwZGPAQeQF-40 "The link could not be embedded because youtu.be does not allow embedding of that video." Anyway - Hania Rani - Nancy Jazz Pulsations 2023 - ARTE concert Just posted a few days ago of the 2023 performance. Worthy as always.

So some Chinese folks were caught smuggling in a grain fungus. They are either overzealous researchers or part of a plot to attack Crops. Either way, not good. Too many bad things are caused by Irresponsible actions like this. Let's hope this isn't an evil plot. If it is, they'll try again.

Visiting around Paris. Paris, Tennessee that is. It's a great place to see nature. But today's weather is a bust. Great retirement location.

This should be landing shortly.

Where did you found the schematic? We canot find anywhere in the thread. maybe you can share the link to the classified? sometimes one can find new sellers searching the pictures. I am deeply sorry I meant the to ask if the center board unnecessary?? is the same true for the board mounted on the sides? if unneccessary why are they there??

If all others considered classic "enjoyable" porn, this is like a really weird japanese porn you cannot "enjoy" cuz of obvious reasons...

I have questions.

Thanks Kevin. I went back and double-checked the schematic. You're right, each 300B does have its own separate filament supply. In this way, would it be possible for me to use four individual 2A/3A DC-DC modules to power them separately? BTW, how’s the D&G project going? I remember it requires something like 10V at 8A or even 10A for the filament supply. That’s already more current than a typical household socket can handle for just the tubes! I’d love to hear more about the D&G if you’re open to sharing. I got the chassis at the end of 2024, the link was expired for a while but i do believe you can find it somewhere else. For GG building guide, you can browse the GG thread, it has all the info and issues you may like to know.

Shazam by The Move (1970) https://album.link/gwvsqbsvnzrxh Example: The short lived but fun 'The Move'.

quotting shawn "I have some concerns if two modules can work in parallel. In Megatron XL, the two 300Bs per channel share the same filament supply" no they do not. each output tube (all 4 of them) has its own filament supply. they have to be seperate supplies for the 300b because they are in the audio circuit. in the d&g i use 2 switching modules in series to get the equivalent for 10v.

I watched the first episode. I hope it gets better quickly. However, I'll admit that I was tired when watching. It's distinctly possible that I dozed for a millisecond. Though Al will atest that I rarely do that.

Please can you share the link? my friend canot find the right one is center board unnecessary?? is the same true for the board mounted on the sides?

You should easily find it on eBay or somewhere else. Regarding the file, it is not mandatory for GG. You should complete the build by populating the GG boards only. Otherwise, you need to figure out the drilling distance to perfectly make the center board fit well, which is unnecessary.

so that chassis in various sizes was available on ebay. i do not know whether it is still available. will have to look later. i know that some people think the tent labs filament supply is gods gift to dht tubes. real fact is that it does not really like hanging off -450v. as it was never designed to do so. there are better, cheaper and smaller ways of doing this.

my friend see your post at head-fi planing chasis for megatron and look very nice look same as chasis you build for kggg look like good chasis many use can you tell where to buy from? can you share the pcb files for the custom pcb in kggg?

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!😊