Thank you so much! It's a ton of fun playing with old tech. with all the resources and information available instantly. I can't imagine how hard it must have been to figure this stuff out back in the 50s!
Very cool build - I especially like the section that describes the PCB milling process - you describe two unknown-to-me software packages that seem to be exactly what I need to mill PCBs on my little 3018 mini CNC setup. I'll have to watch your detailed videos on using the software but I am sold on it already.
Thank you so much! Both DesignSpark PCB (www.rs-online.com/designspark/pcb-software) and FlatCAM (flatcam.org/) are free software, which is insane given how powerful they are. DesignSpark felt really intuitive for me to use, although Kicad seems to be the more popular choice. DesignSpark does have a massive online library where you can search for models that don't come pre-packaged, which is where I found some of the vacuum tube models for drawing schematics (this schematic was drawn in DesignSpark PCB as well: i.postimg.cc/xTnR6Lnh/6-AU6-SR-Hart-Schematic.png). The tube socket models for the PCB I actually built from scratch since I use PCB headers for the sockets, so I'm quite happy with DesignSpark's versatility in the regard. FlatCAM took a while to figure out all the right settings that would work well on our mill, but again our mill is a first generation 3-axis Bridgeport that's being pushed to the limit cutting something so small! I wholeheartedly recommend both of those programs as they have been awesome for me so far!
What a great project! Do you have a final single schematic that includes the new LED circuits? I may build this, except I’ll probably cheat and use a single 24V supply with modern circuitry for the other 2 voltages hidden in the stand.
U.E. Crazy Question: Do you ever check the voltages across the heaters to make sure they are only drawing 6V? And would that give you a hint if they were going to give you problems down the road ???
Yup! That's actually one of the first things I do whenever I build a PCB with the heaters in series. I've had a few times where I accidentally put the wrong tube in place, which totally wrecks the heater balance and can cause some issues. But, if all the heaters are rated at the same current and voltage, they usually have a really consistent 6V drop across them! The only issue comes from warm up time on the occasion with some heaters having a shorter warm up time, causing others to flare up. So far, that hasn't ever been bad enough to cause any problems though.
At 16:47 what pin sockets did you use to make the socket for the tubes? I am really curious because traditional tube sockets have gone super expensive and making your own socket in the PCB itself is really neat and cheap.
Quick question: what are those little ferrule-looking things you use on your tube PCBs instead of sockets to connect the tube pins to the board, and where might one find some available to buy? I didn't see anything other than the usual sockets at AES...might they be something you might find at the likes of DigiKey or Mouser?
I wonder what the voltage drop is across the diode tubes? I was kind of expecting that it would be different enough from the silicon diodes that you would have to change the biasing because the negative supply voltage changed, but apparently not.
Very nice build! .I like the CNC mill of the PCB. Something I want to get into sometime. I just need a mill. For now I have been having my boards made, which just takes the time to wait for them to come in. I am interested in what you used for the tube sockets. What are those pins!? I think that looks a lot nicer than the usual tube sockets.
Thank you very much! You don't actually need a big massive mill like we have, there's a ton of great desktop CNC mills for machining PCBs. They're surprisingly affordable on Amazon as well. I actually ended up teaching myself how to mill PCBs because I mistakenly ordered some PCBs at the beginning of Chinese New Year and a month later they hadn't even shipped yet. Nothing like a little impatience to spur the desire to learn new things, haha. The tube sockets are actually just 1mm PCB header pins ordered from Mouser (www.mouser.com/ProductDetail/Harwin/H3161-46?qs=p%252BybrH12zCFIuSSHm88cAQ%3D%3D). I made a custom socket layout in DesignSpark that has a large pad with a large hole in the center, so I can press those header pins in and then solder them solid. They work surprisingly well and give a really clean appearance. It makes installing and removing the tubes really too. Only drawback is I wouldn't necessarily recommend it for something that's pushing a lot of power and going to be on for long periods of time. If the tubes get really hot, there is a possibility that they can damage the PCB. For all the low voltage, low stress stuff I'm doing, they work perfect though!
Hello, how many amps is the adapter rated at (or how many amps does the circuit needs)? PS. I already bought some tubes and all the parts required for this project. I'm really looking forward to build this thing :)
That's awesome! Definitely keep me updated on how the project is progressing and let me know if there's anything I can help with! The adapter is a run of the mill 24V 1A wall wart that I got off Amazon: www.amazon.com/gp/product/B07VL8W6MQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 The actual logic portion of the circuit requires such little power, I don't even really consider it when calculating required power. The heaters are the real power hungry parts. Each tube requires 300mA at 6.3V, which is 1.89W per tube. So, in total, we need about 7.5W to run the heaters, although it's good practice to overshoot this a bit as the heaters require a bit more juice when first powering up. The 24V 1A wall wart is capable of supplying up to 24W, so you could probably even get away with a 24V 500mA power supply, but I like to go overkill on my power supplies.
@@UsagiElectric Hi, today I assembled the SR flip-flop. But I didn't have access to the 6AU6 so I used 6BE6. Now there is a problem. When I power it up both LEDs light up as expected, but then both of them turn off. For the Hartley oscillator, I used EF800 and on the breadboard, it gave me -12V as it should even though I only had 47uH inductors instead of 56uH. Do you have any idea what may be the problem? If you can give me your mail or something I can send you the scheme and video of how it is (in)working.
@@michalvarsanyi612 That's awesome that you're getting pretty close to working! The 6BE6 is actually a pentagrid converter, so it's a bit different than the 6AU6. It should still be able to work, but it'll have to be hooked up a bit differently. I've never used the EF800, but it sounds like you've got it working pretty well with the Hartley Oscillator, so that's good. The inductor sizes on that can be pretty flexible, so you're definitely on the right track! If you want, hop on Discord (discord.gg/p7UsfHD) and we can chat and share pictures. Or if you prefer, we can chat on Reddit (www.reddit.com/user/Nakazoto) or you can send me an e-mail (Nakazoto at gmail dot com).
@@UsagiElectric Does the wall wart get hot? Each of the four tube filaments draws 300ma, which would be 1.2A total, and your wall wart is only rated for 1A. Has this been a problem at all?
