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Megatron Electrostatic Headphone Amplifier
simmconn replied to kevin gilmore's topic in Do It Yourself
Interesting design! I’d be a bit worried about the thermal and mechanical side of things. The thermal resistance of the heatsink this size is probably going to run above 5C/W without forced air flow. It is going to run too hot to touch at 350V to 400V/20mA (7 to 8W). With 3C/W theta JC on the 10M90S, there is still margin on the die temperature. If I were to design a PCB to be plugged into a tube socket with soldered pins, I’d use slightly undersized pins and whatever copper I can get for adhesion to the board (double layered board with plated-thought holes in 2-mm or thicker PCB), especially if the counterpart is the unforgiving “modern” tube sockets with tulip type spring contacts. Last but not least, when the whole thing gets very warm, I’d use materials with higher working temperature such as ASA or ABS. PLA is probably not going to last very long. - Today
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Ye Macce Threade
Knuckledragger replied to Hopstretch's topic in GoRedwings19's Computer Help Hotline
That's wild, as it uses a white Apple logo some 15 years before it became the company standard. -
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It might be a binder of Apple printed documentation for the Lisa.
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Ye Macce Threade
Knuckledragger replied to Hopstretch's topic in GoRedwings19's Computer Help Hotline
Via Flickr, two fun bits of history: Edit: Anyone know what is that rectangular thing to the left of the Lisa? Behind the "bar of soap" mouse. I think it might be a software box. -
Family started chipping in so I'm now over the 75% threshold. Just a little bit more to go.
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Well that's reassuring. /s
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Megatron Electrostatic Headphone Amplifier
JoaMat replied to kevin gilmore's topic in Do It Yourself
New solid state CCS for Megatron. Now with a third pin for ground. The pins are made from 2.5 mm brass rod, which is almost 0.10 mm thicker than tube pins. PCB is a CNC milled one side 1.5 mm copper clad. So, no copper on top side of PCB. Holes for the three pins are 1.0 mm deep and you have 0.5 mm epoxy laminates left. Transistor pins are protected with heat shrink tube and the exposed metal tab is protected with a 3D printed cover. The screw holding transistor to heat sink is electrical connected to it and to the ground pin. The white base with guide pin is made of three 3D printed parts. -
First human case of flesh-eating screwworm parasite confirmed in US https://www.theguardian.com/us-news/2025/aug/25/new-world-screwworm-flesh-eating-parasite-case-us?CMP=share_btn_url
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That seems really unlikely. If something that wants to kill you is already inside your body, I'd think it would just burrow in further.
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Here are the links that my brother recommended: The League of American Bikers: https://bikeleague.org/#null https://bikeleague.org/ridesmart/ridesmartvideos California Bicycle Coalition: https://www.calbike.org I like blessingx's suggestion of a horn. I have a bell on my e-mtb bike. I also suggest both a front and rear lights to make yourself more visible when not in a group.
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We've watched all four episodes and it's fun. But I have some kind of bumpy rash on the back of my neck and I'm concerned something is going to pop out and kill me.
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Thankfully I live out amongst the farms now. Davis is essentially an island surrounded by a sea of farmland. There are seldom used roads going in basically every direction.
- Yesterday
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I'm not entirely sure what's going on here: $473 in audio plugins for less than $3 with the discount code FUCKUADANDGUITARCENTER because guitar center pissed off Sam Pura.
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Upload, Season 4 just arrived (only 4 short episodes) Mixed emotions...
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There was more grillin' tonight Some of it was plain dirty I was invited to carve And the other meats Result!
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Sorry for the late response. I believe that you are talking about road biking as opposed to gravel or mountain. I don't know much about road biking so I asked my brother, who is a certified road bicycle safety instructor, to send me some links. I'm busy this morning but I'll post them this afternoon. The main thing to remember is that you are basically invisible to drivers. So, anything you can do to make yourself more visible is a plus. But always act assuming that car drivers don't see you when you ride.