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Maybe harder than you anticipate Recently I was sent a not working Blue Hawaii BJT. Turns out the PSU PCB is a clone of Kevins layout ... just flipped upside down, with components firmly mounted on top of the traces ...a year down the road, it went boom, with lifted traces and some literally burned totally. @kevin gilmore has been kind and provided a modified version of his layout to match the mounting studs in the chassis.

I'd use 300b or 2A3 tubes as load be aware that NOS tubes may have different results from new production tubes

Good news: It works! Measured output is 4.9V for the 5V setting, 6.1V for 6.3V, and spot-on 2.5V for the 2.5V setting. I haven’t tested the soft-start function yet — if anyone has good suggestions on how to choose a suitable load resistor for testing, I’m all ears. Bad news: I spent two days figuring out how to hand-solder with a heat pad and heat gun the QFN package. Even when using a stencil, too much paste tends to remain on the pads, which makes them very prone to shorting. As a result, I ended up ruining two boards and some components. At this point, I really don’t feel like assembling the remaining three boards myself. I think it’s best to leave the rest to a proper assembly house.

It’s not hard to do a 1:1 clone of the PCB. It’s also a great interview question for a junior electrical engineer to come up with a circuit that does this. However not a lot of them would probably know how a vacuum tube filament/heater behaves.

The 80's are now in full effect with Tainted Love.

Progress report

The Banjo powered jam band energy of New Monsoon. And a choc-ice.

How Y'All Doin' Novato? Wreckless Strangers @ https://www.novatochamber.com/2025-art-wine-music/

Chocolate Tifin and Nice Cup of Tea with the Brits.

Today ... https://bonair.com/brits/ Lucas electrics has no power here, so here are a few of those that made it.

Personal History by Mary Chapin Carpenter (2025) https://album.link/gtnmzvcxr3szp Example: Warm and sometimes brooding. A set of tunes from one that seems to know who they are and where they are in their life.

The Blue Nile - A Walk Across the Rooftops Shpongle - Codex VI

Pan Seared Halibut, Lemon Rice, minted peas, lemon / dill / yoghurt dressing.

Yeah Yeah another Rick Video - but I had never heard the isolated tracks before - pretty darn cool.

It's impressive. Art is subjective. This piece, especially. https://sfstandard.com/2025/04/20/naked-lady-sculpture-sf/ https://sfstandard.com/2025/04/20/naked-lady-sculpture-sf/

Does the new sculpture look better in person?

Hello Friends, a nice family shot with no load, no current limitation. Have to figure out why the bias doesn't kick in at 580V, otherwise quite happy. Edit, discovered it's the dmm impedance, bias is just right 👍

That was fast! Thanks a lot.

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