DIY Project Show & Tell

[Jim the Oldbie]

Hi Kids,

Sonik Wiz's recent DIY post made me think this might be a good general-purpose topic. What are you all building out there? Here's one to kick it off:

I love music, and I love electronics. I also have a fondness for electronic music for some reason. As a nerdy teenager in the mid-'70s, I spent hours & hours at the local music store (where I later wound up working for 32 years), messing with one of the synthesizers they had on display, an ARP 2600. This now-classic synth was used by Edgar Winter, Joe Zawinul, and many many others, and it's the one that taught me how synthesizers work.

Unfortunately for me, the price has always been a non-starter. The 2600 sold for about $3400 USD back in the day; and if you want a nicely restored one now, it'll set you back around $10,000-15,000. Sorry, but nope.

BUT! Now you can buy a reasonably-priced replica of the original 2600, called the TTSH (Two Thousand Six Hundred). It's available in various configurations: as a completely assembled & tested unit, a complete kit of parts, or just individual bits like the front panel & PC boards. I work as an electronics tech, and I used to love building Heathkits as a kid, so of course the complete kit version was a no-brainer. It arrived last week:



Here's a pic of the finished version, and a great one of Edgar in the studio with his 2600:

I haven't been this excited about a project since I was a kid! Not only do I finally get to own a 2600, but I get to build it from a box of loose parts!! Somebody pinch me!

Okay, I showed you mine, now show me yours! What do you guys have splayed out across the dining room table??

 

[Sonik Wiz]

Hi Kids,

Sonik Wiz's recent DIY post made me think this might be a good general-purpose topic. What are you all building out there? Here's one to kick it off:

I love music, and I love electronics. I also have a fondness for electronic music for some reason. As a nerdy teenager in the mid-'70s, I spent hours & hours at the local music store (where I later wound up working for 32 years), messing with one of the synthesizers they had on display, an ARP 2600. This now-classic synth was used by Edgar Winter, Joe Zawinul, and many many others, and it's the one that taught me how synthesizers work.

Unfortunately for me, the price has always been a non-starter. The 2600 sold for about $3400 USD back in the day; and if you want a nicely restored one now, it'll set you back around $10,000-15,000. Sorry, but nope.

BUT! Now you can buy a reasonably-priced replica of the original 2600, called the TTSH (Two Thousand Six Hundred). It's available in various configurations: as a completely assembled & tested unit, a complete kit of parts, or just individual bits like the front panel & PC boards. I work as an electronics tech, and I used to love building Heathkits as a kid, so of course the complete kit version was a no-brainer. It arrived last week:

View attachment 45334 View attachment 45335

Here's a pic of the finished version, and a great one of Edgar in the studio with his 2600:
View attachment 45336 View attachment 45337
I haven't been this excited about a project since I was a kid! Not only do I finally get to own a 2600, but I get to build it from a box of loose parts!! Somebody pinch me!

Okay, I showed you mine, now show me yours! What do you guys have splayed out across the dining room table??

I think DIY, like HAM radio, is just not as popular as it once was because most everyone can do on the PC what used to be done with hardware. Besides you Par4ken is the only other DIY'er I know on the forum. But I am happy to say at one time every pice of gear that I had (except fot the VCR) was modified in some way or repaired . I even slogged my way through the Pioneer DVL-700 LD service manual & figured out how to defeat the always on video noise reduction (you pull a LSI chip out of it's socket, bend a pin up & connect it to ground).

I have posted about other projects I've dome here: the Quadraflange, Chase RLC-1, mods to the Space Matrix deecoder, etc. But man-o-man never built anything like the 2600 synthesizer! That is incredibly cool! Now I'm not a musician at so I wouldn't build that anyway. But I have built quite a few PAIA/SWTP stuff. Always read Craig Anderton's articles & I always learned something.

 

[quadsearcher]

I repaired a 2600 years ago. It was "just" a shorted tantalum cap on the output, allowing it to pass DC. Fell in love with the thing. With normalled patches, it practically plays the opening to Weather Report Birdland by itself. And more. Well not really, but I'm not a keyboard player and it was easy to pick out, because the notes sounded just like the record (with some playing with settings). I didn't have the cash to buy it. Yes I would enjoy the kit.
My favorite of projects from the 80s (maybe that was 70s?) was just the effects module from PAIA Stringz n Thingz. Bought the board and stuffed it with stock parts and Radio Shack, put it and controls in an old radio case. Kind of like multiple Leslies except done by voltage controlled delays driven by separate LFOs.

 

[Sonik Wiz]

Here's something I don't think I've posted previously. Not quite the usual DIY project but fun, pretty easy, & impressive.

Like others here I have a good 'ol Panasonic quad scope at the top of my gear rack. Works perfect, bright trace. It does take up a bit of space & I needed that top shelf to put in something else. So I pulled the Q Scope.

After a few weeks I started to miss it. I had an inspiration to use it located out of the way but put the trace on my 8' big screen. I have a closet just to the left of the rear of my audio rack with shelves so I put it there. It was too wide so I turned it vertically & the CRT was now on the "bottom". I have multiple generations of video cameras & I chose an old VHS-C unit for it's size & good close up capability. It was roughly put in position on top of some old Pop Electronics mags & supported laterally with a couple of bricks each side. It was a little clumsy but it didn't take long to get zoom/focus positiend & tweaked for no perspective didtortion. A composite video cable RG6 went from the camera to an input on the projector.

Since the Panasonic display is square (that is the bezel with the corner lights) & the vid cam format was square, and my screen is 4' x 7' the image filled top to bottom. I had a 4 ' Quad scope image.

It was as I said pretty impressive but fun. I got a blast out of it at first but eventually found it too distracting when listening to music. It's one thing to glance over at a 4" display but to have your attentionn riveted on a big display is straight ahead is too much. In audio vs video audio always takes the priority so eventually I quit using it. The Panny scope is now back home, sitting just above the Surround Master v2.

 

[Soundfield]

I think DIY, like HAM radio, is just not as popular as it once was because most everyone can do on the PC what used to be done with hardware. Besides you Par4ken is the only other DIY'er I know on the forum.

Some others of us still dabble in the dark arts Sonik !.....

I previously posted about my little Hafler line level decoder:
HAFLER DECODER BOX
Experiment over, I gave it to a friend of mine recently who wanted to add Hafler surround speakers to his system – but could not do so conventionally by simply sticking the speakers across the hot terminals of the power amps as, like me, has valve amps with no common reference (being transformer coupled). It works really well and he’s delighted with the results – so much so that I might build him another with a delay circuit which improves on the effect, and a rear level control.

I was also in the process of building a three band full logic SQ decoder using the Motorola chipset. I designed a PCB for a single channel decoder and etched a set of three of them old style using ferric chloride (difficult to get these days)! One of the decoder boards and my hand drawn artwork is shown below:

The intention is / was to feed them from a three band filter and to have different logic attack and decay characteristics in the decoders in each band. I’ve got all of the components sitting in a box, but the urge to complete the project was rather undermined by the arrival of the Surround Master! I may finish it one day, but as we all know, the path to Hell is paved with good intentions!

 

[Sonik Wiz]

Some others of us still dabble in the dark arts Sonik !.....

I previously posted about my little Hafler line level decoder:
HAFLER DECODER BOX
Experiment over, I gave it to a friend of mine recently who wanted to add Hafler surround speakers to his system – but could not do so conventionally by simply sticking the speakers across the hot terminals of the power amps as, like me, has valve amps with no common reference (being transformer coupled). It works really well and he’s delighted with the results – so much so that I might build him another with a delay circuit which improves on the effect, and a rear level control.

I was also in the process of building a three band full logic SQ decoder using the Motorola chipset. I designed a PCB for a single channel decoder and etched a set of three of them old style using ferric chloride (difficult to get these days)! One of the decoder boards and my hand drawn artwork is shown below:

View attachment 45404

The intention is / was to feed them from a three band filter and to have different logic attack and decay characteristics in the decoders in each band. I’ve got all of the components sitting in a box, but the urge to complete the project was rather undermined by the arrival of the Surround Master! I may finish it one day, but as we all know, the path to Hell is paved with good intentions!

Hey Soundfield
I just wanted to say what a great looking board layout that is. IIRC the Vista/Photolume SQ decoder kit in Pop Electronics (?) didn't look near as clean. I have designed & etched more than a few PCB's myself so I understand the efforts. Like you I also have some etched & drilled & never used. At least I worked in the photographic field most of my career so I always had easy access to shooting the liths.

And I thnk that's very clever to use tri-band decoding with the Motorola 3 chip design. Even more clever if you could design the phase shift components to be more accurate for those pass bands. Since the chips use DC control coltages for balance/level/dimension you would now have to use ganged controls. Tri-band decoding would certainly reduce SQ Fool Logic side effects. Better than chasing down the Paramatrix rabbit hole.

 

[Soundfield]

Hey Soundfield
I just wanted to say what a great looking board layout that is. IIRC the Vista/Photolume SQ decoder kit in Pop Electronics (?) didn't look near as clean. I have designed & etched more than a few PCB's myself so I understand the efforts. Like you I also have some etched & drilled & never used. At least I worked in the photographic field most of my career so I always had easy access to shooting the liths.

And I thnk that's very clever to use tri-band decoding with the Motorola 3 chip design. Even more clever if you could design the phase shift components to be more accurate for those pass bands. Since the chips use DC control coltages for balance/level/dimension you would now have to use ganged controls. Tri-band decoding would certainly reduce SQ Fool Logic side effects. Better than chasing down the Paramatrix rabbit hole.

Thanks Sonik, yes, the PCBs were something of a labour of love - I even had to build my own UV light box to expose the photo-resist. If the project ever gets to fruition I will be trying different phase shift networks. The ganging of the control voltages across the three parallel decoders offers opportunities but is a bit fiddly. I wonder why no one has ever tried this arrangement before?!!

 

[mlrocker]

TTSH link

 

[barfle]

Well, @Sonik Wiz suggested I post my mods to my Heathkit Audioscope here when I mentioned it in a post on the new members thread. And, it seems like it’s time to revive this thread anyway.

I’m a retired EE, and probably the most rewarding time I had in my career was designing circuits, so I’m not exactly poking around in the dark. But, of course, every new design is destined for troubleshooting, hopefully before it goes into production rather than after. One of my axioms about designing stuff is “The only thing I ever designed and built that worked right the first time was an extension cord.” That’s not exactly true, but it shows that no matter how much you think you know, nature has a surprise or two for you.

While the audioscope is, sadly, packed away and I only have faulty memories of exactly what I did with it, I do recall that I got rid of the NE-2 indicators and replaced them with green LEDs when those became available. I’m pretty sure many of us remember when red was the only color you could get LEDs in, and the green ones show theough the green plastic screen far better than the orange neon bulbs did. That took some changing of the drive voltage and current, of course.

Another thing I did was twist the display for the stereo lissajous pattern. The original design, IIRC, had the left channel as vertical and the right channel as horizontal. I wanted it to turn 45 degrees counter-clockwise, so I wrapped the CRT with 30 guage wire and switched the current through that coil of wire so it would only pass while that mode was operational. It wasn’t perfect, because apparently the residual metal around the CRT distorted the display for the other modes, notably the single-channel traces looked like they were, as I described it, “slanted script.” For some reason, the horizontal and vertical were no longer perpendicular. I intend, at some point, to change that idea to a pair of sum and difference op-amps to correct that display, but it’s not high on my list yet.

I’ve already covered my home theater build in detail on a dedicated thread. When we moved to Idaho, I had to dismantle my previous build and store all the gear in order to sell our house in Virginia. It took us a year to find this house, and another year to get the room built so it was at least functional. In that time, I discovered that the movers beoke one of my turntables, and that my three Emotiva Stealth 8 studio monitors (speakers with built-in biamplification) had somehow started sounding like crap. Emotiva was little help beyond sending me schematics, and without the proper test gear, I couldn’t really address the issues.

Also, I have a little organ chord generator called the “PIAI Stereo Chord E.G.G. (Electronic Gratification Generator).” It has a chip called a “top octave generator” that puts out the 12 tones of the chromatic scale, and a set of switches that randomly select major chords of those tones. Several of the timing capacitors in that unit had dried out, so while it put out some tones, it wasn’t working correctly.

About 6 months ago, I bought a remarkable diagnostic tool. It’s primarily an oscilloscope, which I’ve used since high school, but it also has a spectrum analyzer and two signal generators. The manual is over 300 pages long, so I doubt that I’ll get to master it all!

But the oscilloscope functions are pretty familiar, and I was able to use it to track down the bad caps in the E.G.G., and it’s working as it should. If I just want to chill, it’s pretty nice.

I also used the ‘scope to track down dried-out capacitors in my Emotiva monitors. I found it disturbing that a speaker less than six years old had dried-out capacitors that I replaced with 40-year-old capacitors from my stock of parts left over from when I had my own business.

Anyway, I have about a dozen pieces that need attention before they’re ready to go into the system or to sell. I’ll be posting those efforts here as they happen. My next project is probably my laser disc player. I believe its only issue is a switch that senses the drawer being closed, but I haven’t taken the cover off to check. Hopefully, I won’t be spending six hours a day shoveling snow all winter, and I’ll have a chance to see how bad the break is, and what else might need attention.

 

[Sonik Wiz]

Well, @Sonik Wiz suggested I post my mods to my Heathkit Audioscope here when I mentioned it in a post on the new members thread. And, it seems like it’s time to revive this thread anyway.

I’m a retired EE, and probably the most rewarding time I had in my career was designing circuits, so I’m not exactly poking around in the dark. But, of course, every new design is destined for troubleshooting, hopefully before it goes into production rather than after. One of my axioms about designing stuff is “The only thing I ever designed and built that worked right the first time was an extension cord.” That’s not exactly true, but it shows that no matter how much you think you know, nature has a surprise or two for you.

While the audioscope is, sadly, packed away and I only have faulty memories of exactly what I did with it, I do recall that I got rid of the NE-2 indicators and replaced them with green LEDs when those became available. I’m pretty sure many of us remember when red was the only color you could get LEDs in, and the green ones show theough the green plastic screen far better than the orange neon bulbs did. That took some changing of the drive voltage and current, of course.

Another thing I did was twist the display for the stereo lissajous pattern. The original design, IIRC, had the left channel as vertical and the right channel as horizontal. I wanted it to turn 45 degrees counter-clockwise, so I wrapped the CRT with 30 guage wire and switched the current through that coil of wire so it would only pass while that mode was operational. It wasn’t perfect, because apparently the residual metal around the CRT distorted the display for the other modes, notably the single-channel traces looked like they were, as I described it, “slanted script.” For some reason, the horizontal and vertical were no longer perpendicular. I intend, at some point, to change that idea to a pair of sum and difference op-amps to correct that display, but it’s not high on my list yet.

I’ve already covered my home theater build in detail on a dedicated thread. When we moved to Idaho, I had to dismantle my previous build and store all the gear in order to sell our house in Virginia. It took us a year to find this house, and another year to get the room built so it was at least functional. In that time, I discovered that the movers beoke one of my turntables, and that my three Emotiva Stealth 8 studio monitors (speakers with built-in biamplification) had somehow started sounding like crap. Emotiva was little help beyond sending me schematics, and without the proper test gear, I couldn’t really address the issues.

Also, I have a little organ chord generator called the “PIAI Stereo Chord E.G.G. (Electronic Gratification Generator).” It has a chip called a “top octave generator” that puts out the 12 tones of the chromatic scale, and a set of switches that randomly select major chords of those tones. Several of the timing capacitors in that unit had dried out, so while it put out some tones, it wasn’t working correctly.

About 6 months ago, I bought a remarkable diagnostic tool. It’s primarily an oscilloscope, which I’ve used since high school, but it also has a spectrum analyzer and two signal generators. The manual is over 300 pages long, so I doubt that I’ll get to master it all!

But the oscilloscope functions are pretty familiar, and I was able to use it to track down the bad caps in the E.G.G., and it’s working as it should. If I just want to chill, it’s pretty nice.

I also used the ‘scope to track down dried-out capacitors in my Emotiva monitors. I found it disturbing that a speaker less than six years old had dried-out capacitors that I replaced with 40-year-old capacitors from my stock of parts left over from when I had my own business.

Anyway, I have about a dozen pieces that need attention before they’re ready to go into the system or to sell. I’ll be posting those efforts here as they happen. My next project is probably my laser disc player. I believe its only issue is a switch that senses the drawer being closed, but I haven’t taken the cover off to check. Hopefully, I won’t be spending six hours a day shoveling snow all winter, and I’ll have a chance to see how bad the break is, and what else might need attention.

Great post & thanks for revitalizing this thread!
The one & only local quad friend I had also had a Heathkit Quadscope in his setup. It's definitely classier looking than my Panasonic & has a few more functions. Maybe 15 years ago I replaced the original green CRT with a dual phosphor Dumont 4FP7. The P7 has a yellow long persistence and a very short persistence blue phosphor. Originally designed for radar this allowed you to see where the music is and where it had been.

It was a pain in the butt to install partly because the deflection electrodes were not in tube base but stuck out of the neck like those little anode connectors do. Also it is a square flat front screen & has a couple extra electrodes made to maintain focus side to side. I could not do that so it got rather blurry at the sides. Also even tho the slow persistence is not adequate for SSTV it is sometimes too slow to keep up with the music & kinda turns into a diffuse glow while the blue just zips around. It was very pretty but had some problems & didn't live up to my expectations. So it was replaced by the Wurlyscope.

Speaking of shoveling snow, do ya ever think that DIY 'tronics is seasonal? Not if you live somewhere most always warm but here we've 4 or 5 seasons. Summer it's so hot & humid it's really nice to have a good reason to hang out in my basement. In winter I don't have as much shoveling to do as you, but if you arent going to football games than winter is great time to hunker down in the basement with a nice warm soldering iron.

 

[barfle]

The Wurlyscope did seem to be a pretty cool toy, but with my Heathkit functional (I’m pretty sure), it didn’t seem like something I could use. My main listening system has an Atari Video Music in the rack, waiting to be connected for circumstances where I have no video (like LPs).

All in good time. Nothing is quick or easy any more (if it ever was).

I’ve mentioned on QQ that I have the engineering prototype of a 100WPC power amp that Altec Lansing couldn’t get to work well. IIRC, SNR was around 60db, probably because of a rather bizarre diff amp gain stage. It’s been sitting in a carton for fifty years, and it’s always been something I wanted to make work well. It would be the perfect companion to my Altec 724 tuner/preamp and University E8 prototypes. Of course, I’m considering making the power amp quad and adding an Involve decoder to the 724.

Yep, lots on my plate for someone my age. I hope I live long enough.

 

[Sonik Wiz]

The Wurlyscope did seem to be a pretty cool toy, but with my Heathkit functional (I’m pretty sure), it didn’t seem like something I could use. My main listening system has an Atari Video Music in the rack, waiting to be connected for circumstances where I have no video (like LPs).

All in good time. Nothing is quick or easy any more (if it ever was).

I’ve mentioned on QQ that I have the engineering prototype of a 100WPC power amp that Altec Lansing couldn’t get to work well. IIRC, SNR was around 60db, probably because of a rather bizarre diff amp gain stage. It’s been sitting in a carton for fifty years, and it’s always been something I wanted to make work well. It would be the perfect companion to my Altec 724 tuner/preamp and University E8 prototypes. Of course, I’m considering making the power amp quad and adding an Involve decoder to the 724.

Yep, lots on my plate for someone my age. I hope I live long enough.

I was not familiar with the Altec 724 unit but I found the data HERE. Those specs are great for that time period & I bet it looked really slick in person. So, I can't help but wonder if this is a unit you had a hand in designing?

 

[barfle]

I was not familiar with the Altec 724 unit but I found the data HERE. Those specs are great for that time period & I bet it looked really slick in person. So, I can't help but wonder if this is a unit you had a hand in designing?

No, that was before my time designing. I was an engineering tech at Altec in the '73-'74 time frame, and the 724 was already a product, as was the 725 receiver of the same design. The 100 WPC power amp was supposedly ready for prototype, but as I've noted, it was noisy, and they gave up on it. I was able to score the parts in a surplus sale they had about a year after they abandoned the project. It can look very nice, but it's going to need a quiet voltage gain stage.

Interestingly enough, University Sound was a division of Altec at the time (no idea if the brand even exists now), and they had a pair of prototype 3-way speakers called "E-8." I scored both of those at the same surplus sale with a little help from a friend, and they served me well for 40 years+. Amazing that the surrounds never came close to failing.

 

[Sonik Wiz]

Per @barfle :

One of my axioms about designing stuff is “The only thing I ever designed and built that worked right the first time was an extension cord.” That’s not exactly true, but it shows that no matter how much you think you know, nature has a surprise or two for you.

Good one! Any custom length extension cord I've made has worked well too! But I've had some other interesting experiences.

My first real project when I was 12>13 yo was an Allied Knight Kit BCB XMTR. I figured the only thing cooler than building a radio was to be able to talk over one. So I put it together, turned on & nothing smoked. I was adjusting the little mica washer tuning cap when ZAP! A bright flash & a spark--- I swear this is how I remember it--- from the anode of a tube thru the glass envelope & striking the metal blade of the screwdriver I was holding. Quickly turned off, re-checked & found my error. Then came my first experience in de-soldering.I corrected it & worked great after that. However I discovered my family had zero interest in hearing me play Monster Mash & Smoke Gets in My Eyes over the family intercom.

In the late 60's wonderful things called SCR's became commonly available. Those with a soldering iron wanted to make light dimmers & color organs with them. Me too. I purchase one big stud mount (TO-208????) SCR & using a magazine schematic hooked up a light dimmer circuit before I made a color organ. I don't know what I did wrong but with a 60 watt bulb attached I flipped the power & BAM! The thing exploded like a firecracker. I'm lucky I wasn't injured by the shrapnel!

My next creation was the SSS: Scared Shitless Shield. I had a spare piece of reasonably thick Plexiglas, maybe 3' x 4' and I built a freestanding wood frame to put it in. This way I could put the next project all the way across the basement room, I stand at the other with an extension & plug it in while reasonably protected. Fortunately my skills improved & I moved out of the phase of catastrophic testing after that.

 

[barfle]

In high school, I had a subscription to Popular Electronics. I also was enrolled in a class called Electronics, but it was a shop class and not really one where you got to understand what a circuit actually did. Probably because the instructor didn’t know much himself, but I digress. One issue in 1964 had a project of building a Tesla coil. I had seen the Tesla coil at the Griffith Observatory before, and thought it was cooler than dry ice, so I built it, pretty much according to the instructions, although there were some materials I didn’t know how to get. I used some plastic drain pipe for the secondary form, and there was about 1500 feet of (IIRC) 30 ga. wire on it. With 1000 feet on a spool, making the splice non-obvious was one of my early challenges. It looked great once I sprayed it with plastic coating.

There was an HF “oscillator” that was a 15kV neon sign transformer (fun making a Jacob’s ladder), a spark gap, and a capacitor made from window glass and galvanized sheet metal. My first time firing it up, an arc formed around the edge of the glass and cut a line through the glass to the edges of the sheet metal. Live and learn, and I had to buy the replacement glass myself.

Eventually, I got it going, and when it was running, nobody for about a half-mile was watching TV. I made a vane for the top, and the ionic propulsion would make it rotate. I could also light up a neon tube held about 3 feet away. It took 2nd place at an industrial arts fair that included all the counties in SoCal.

 

[Sonik Wiz]

In high school, I had a subscription to Popular Electronics. I also was enrolled in a class called Electronics, but it was a shop class and not really one where you got to understand what a circuit actually did. Probably because the instructor didn’t know much himself, but I digress. One issue in 1964 had a project of building a Tesla coil. I had seen the Tesla coil at the Griffith Observatory before, and thought it was cooler than dry ice, so I built it, pretty much according to the instructions, although there were some materials I didn’t know how to get. I used some plastic drain pipe for the secondary form, and there was about 1500 feet of (IIRC) 30 ga. wire on it. With 1000 feet on a spool, making the splice non-obvious was one of my early challenges. It looked great once I sprayed it with plastic coating.

There was an HF “oscillator” that was a 15kV neon sign transformer (fun making a Jacob’s ladder), a spark gap, and a capacitor made from window glass and galvanized sheet metal. My first time firing it up, an arc formed around the edge of the glass and cut a line through the glass to the edges of the sheet metal. Live and learn, and I had to buy the replacement glass myself.

Eventually, I got it going, and when it was running, nobody for about a half-mile was watching TV. I made a vane for the top, and the ionic propulsion would make it rotate. I could also light up a neon tube held about 3 feet away. It took 2nd place at an industrial arts fair that included all the counties in SoCal.

It should have won first place!

 

[gene_stl]

Aah, Popular Electronics!

 

[LB-V]

There was an HF “oscillator” that was a 15kV neon sign transformer (fun making a Jacob’s ladder), a spark gap, and a capacitor made from window glass and galvanized sheet metal. My first time firing it up, an arc formed around the edge of the glass and cut a line through the glass to the edges of the sheet metal. Live and learn, and I had to buy the replacement glass myself.

Holy cow. I thought I was the only person in the world...my father and I made what we called a "Tesla Coil" one year for my science fair project. It was exactly that: we got a transformer, had that spark gap and made a very large capacitor with glass and tin. We even rolled the fine winding wire for a coil / inductor that was near 3 feet tall. Then we had a copper toilet bowl float on the top of that.

We set it up in the gymnasium and let it rip. My teachers eyes lit up when the entire gym lights dimmed for a moment and the smell of ionized air began permeating the area. The crackling and popping of the air gap was incredible.

We lit up a flourescent tube through the air.

After my short demo, they deemed it too dangerous to demonstrate further. My instructor asked, well, where's the demonstration write up? I was like huh? I just showed you how it works. I explained it, but I was dinged pretty heavy for just showing up with a wicked device but no narrative.

I loved that moment when my instructor was contemplating running for his life or seeing it through.

 

[barfle]

I still have the magazine!

 

[Sonik Wiz]

I still have the magazine!

Amy estimate what the Farad rating might be for a capacitor like that?