Ultimate Apocalypse Mojo Build Recommendations, Please!

[Fancy Lime]

Hi there,

I somehow got it into my head to build a treble booster with ridiculous over the top parts and construction specs*. Something that will survive the end times. No clue what gave me that idea...

Metal can transistors are a must, obviously. Probably two 2N2907A** in TO-18 cases, piggybacked. Any other suggestions?

For resistors I thought going with 2W metal film. I don't really feel like using something that is actually going to perform worse just to collect extra mojo points on 100W carbon resistors. Or maybe Dale CMF55 resistors? They are only 1/4 watt but they look cool and come in very obscure values, which is definitely a plus here. Does anyone know larger, higher power resistors that come in 51.1k ±1%***

pF range caps will be mica, of course. Larger ones will be some high voltage film caps. Any suggestions?

Now the big question: What type of construction? I was thinking turret board but that seems to be quite the hassle for a small one-off project, when making ones own boards. Pre-fab turret boards would be an option but they only seem to come in two types: too big for anything smaller than a full tube amp project, or made out of solid unobtanium. So what else is going to survive an asteroid impact? Cordwood? Point-to-point between screws bolted right onto the enclosure (carefully isolated from it somehow)? Maybe screws through a lid made of perspex to show off the interior? It is going to have an interior lit with amber LEDs anyway, whether anyone can see it or not Does anyone want to use this opportunity to show off their mojo builds?


Cheers,
Andy


* Yes, I am aware that this serves no purpose. It simply seems fun to do, for some reason. The whole thing is mostly supposed to look good.
** PNP = extra mojo!
*** Because that definitely makes a huge difference compared to 47k.

[EBK]

Yes, I am aware that this serves no purpose. It simply seems fun to do, for some reason.

That's my favorite reason! 

I had this idea once for a diorama-style circuit construction, perhaps something that makes the parts look like they are engaged in an epic battle.  I should throw that in the Steal My Idea thread.... 

[aron]

Point to point like the old LPB-1! Would look cool with plexiglass.

[rockola]

Larger ones will be some high voltage film caps. Any suggestions?

I'm laying out a PCB for the Very Simple Phono Stage by phonoclone.com (they have a PCB available for those so inclined). It calls for two non-polar 2u2 caps. The original BOM has a 400V, 17.5mm diameter axial:
https://www.mouser.fi/ProductDetail/80-C4GAFUC4220AA0J

I ended up going for a 160V box cap the size of a Lego brick:
https://www.mouser.fi/ProductDetail/80-F461DJ225J160L

[niektb]

Why would you want to have such high voltage caps? It is known that these have worse characteristics such as more high-frequency leakage and stuff... (at least i'm very sure that's the case for elco's, I work at a HiFi manufacturer haha)

And why not design your own PCB? Depending on the company you order them, you can choose you're own colors and do all kinds of fun with silkscreen graphics

[willienillie]

Does anyone want to use this opportunity to show off their mojo builds?

I have long thought that there should be a "mojo build" thread in the pictures section.  Because at least half the reason to use mojo parts is because they look cool, might as well make a point to show them off.

[amptramp]

Nothing survives the apocalypse like doorknob capacitors:



The 500 pF 20 KV size was common in black and white televisions as the high voltage filter capacitor for the flyback supply that operated at the horizontal sweep frequency of 15,750 Hz.  They were available in 10 to 1000 pF sizes and used on transmitters as well.

[Fancy Lime]

Why would you want to have such high voltage caps? It is known that these have worse characteristics such as more high-frequency leakage and stuff... (at least i'm very sure that's the case for elco's, I work at a HiFi manufacturer haha)

And why not design your own PCB? Depending on the company you order them, you can choose you're own colors and do all kinds of fun with silkscreen graphics

Why the overpecced (overspec'd? over specked?) caps and resistors? Because mojo! What I am planning is not going to be practical by today's standards. I want to build something like they did in the 60's but with as much style as I can. And NASA specs! Or at least the illusion of it and that overly rugged, nuke proof look that the Apollo computers had. I am a big fan of the post-apocalyptic science fiction of the mid 20gh century (Philip K. Dick, Harry Harrison...). And now we live through exactly the sort of pandemic that is often cited as the beginning or early omen of the catastrophic events in these novels. This is what inspired me to the idea of an old school, nuke proof effect. So no, PCB is not an option for this particular thing. I may, however, just for the fun of it, make a super miniaturized SMT version of the same circuit or something very similar. This should be small enough to simply tape the pcb on the back of a 16mm pot.

Larger ones will be some high voltage film caps. Any suggestions?

I'm laying out a PCB for the Very Simple Phono Stage by phonoclone.com (they have a PCB available for those so inclined). It calls for two non-polar 2u2 caps. The original BOM has a 400V, 17.5mm diameter axial:
https://www.mouser.fi/ProductDetail/80-C4GAFUC4220AA0J

I ended up going for a 160V box cap the size of a Lego brick:
https://www.mouser.fi/ProductDetail/80-F461DJ225J160L

I bought a box of electronics parts at a yard sale recently. It had a 10μF, 250V Visaton film cap in it, which I may end up using for this project. It's the size of a mini mars bar.

Does anyone want to use this opportunity to show off their mojo builds?

I have long thought that there should be a "mojo build" thread in the pictures section.  Because at least half the reason to use mojo parts is because they look cool, might as well make a point to show them off.

+1 for that! If it won't happen before I've build this, I am going to start that.

Nothing survives the apocalypse like doorknob capacitors:



The 500 pF 20 KV size was common in black and white televisions as the high voltage filter capacitor for the flyback supply that operated at the horizontal sweep frequency of 15,750 Hz.  They were available in 10 to 1000 pF sizes and used on transmitters as well.

For small value caps, these look great. For the power supply filter cap, I'd love a axial wet tantalum capacitor. However, I don't quite see myself shelling out triple digit dollars for a single cap. Holy funk, these things are expensive! Well some are under 100$ but still... I need to find me a space shuttle scrap yard.

Andy

[davent]

Larger ones will be some high voltage film caps. Any suggestions?

I'm laying out a PCB for the Very Simple Phono Stage by phonoclone.com (they have a PCB available for those so inclined). It calls for two non-polar 2u2 caps. The original BOM has a 400V, 17.5mm diameter axial:
https://www.mouser.fi/ProductDetail/80-C4GAFUC4220AA0J

I ended up going for a 160V box cap the size of a Lego brick:
https://www.mouser.fi/ProductDetail/80-F461DJ225J160L

I used 4u7 plastic caps in mine. I think i was still using photobucket at that time, i can see the picture fine but they may be photobucket messed...

https://www.diystompboxes.com/smfforum/index.php?topic=116388.msg1077390#msg1077390

dave

[Fancy Lime]

@Dave
Yes, that's the sort of thing I'm talking about. I have to check my usual sources.


In the meantime I strayed away from turret board and started to favor old school point to point with terminal strips like the original Dallas Rangmaster and many of it's contemporaries. So I googled that for some inspiration only to find tons of Mojo Builds based on that exact same idea. The Analogman version is pretty sweet, as always (http://www.analogman.com/beano.htm), and so is the Fuzzlord one (https://youtu.be/wbWlLXaaKVY?t=879).

I am also leaning toward NPN for practical reasons. I figure if I use an appropriately insane case, I don't loose too much mojo So I am considering a pair of 2N2219A in TO-39 packaging. TO-5 would be nicer but seems difficult to come by. Am I informed correctly that the 2N2219A is the otherwise identical high current brother of the 2N2222A?

Andy

[niektb]

I happen to have a working vintage lab power supply sitting on my workbench right now, which is more than 45~50 years old (the first were manufactured in 1970 according to the internet). I screwed it open and took a couple of photos. Maybe you can use it as inspiration!