Ever Have One of THOSE Days?


Well I did.
Typically Fridays are my “lab” days. My only day out of the week when I have the entire day to myself to work on my projects and just bury myself in my own little world of evil genius-ness. Some days I get more accomplished than others, but typically I don’t walk away feeling completely frustrated like I did at the end of the day yesterday. Everything I did wound up in the shit-can. I guess I can look at all of it as a learning experience however. I learned a lot about what NOT to do… let me expand..

To Glow or Not to Glow?

For my Vector Amp project I had decided to not waste money building an actual tube amplifier due to the cost of building an amp that had sufficiently cool-looking tubes. I decided I’d just get some cool looking large tubes and hook up the heaters to get that cheery tube glow without dropping bank on huge transformers to build an actual circuit. So I bought myself a KT-88 power tube and a matching socket from Parts Express. This is a cool looking tube. There are cooler and larger ones out there, but the KT-88 runs about 25 to 30 bucks, so it was in my price range for experimentation.

I’d had an idea to build a small polished wooden box with a copper plate on top holding a glowing vacuum tube. I thought it might be a cool little desk accessory for those who dig vacuum tubes and steampunk stuff.. nothing too complex, just a cool little amusement. I figured this was a great chance to try out my construction ideas for the vector amp on a smaller scale before pulling the trigger. I just needed a few things from the Depot and Radio Crack. A 1-1/8″ hole saw, some wood, and a transformer. Most of the other things I had.

So Friday morning I hopped on my trusty steed (my bicycle) and rode up into new town to make my weekly sojourn to Home Depot. It’s a nice leisurely 2 or so mile ride, and it makes for a nice start to the day.

I picked up some brass nuts and bolts, a hole saw, and a small piece of 1/2″ Oak for the base. Across US-1 from Home Depot is the local Radio Shack, so I popped over there to buy a transformer to power my tube. The guy behind the counter looked at me like I was speaking swahili when I asked for a center-tapped transformer. He then led me to the phone chargers. No, I explained.. a bare transformer. OH he says, I have to go in back to find those.

After about 10 minutes he returned carrying a cardboard box with about 20 transformers dumped in it. He apologized for the state of the stock system and helped me dig for the one I was looking for. After a bit we located the 12V (6-0-6) transformer. I needed 1.6 amps, but they only had 1.2 and 3 amp versions.. I opted for the smaller one just because I didn’t think it would matter terribly since I wasn’t trying to actually make something to spec.

Back on my bike, I pedaled my way home. I walked in the door at 5 minutes to noon.. what timing! Noon in Key West is a pivotal time in the day.. time for a bloody mary.

Drink in hand I made my way back to the lab (a workbench in the corner of the bedroom) and began to put my evil plan into play.

Fail number One.

The tube wouldn’t glow. It got warm, so I knew the heater was working, but it certainly wasn’t glowing like I know tubes do. I had a couple small tubes lying around, and they glowed fine when I hooked them up to the transformer. Dejected, I decided that my transformer pumping out 1.2 amps wasn’t sufficient to fire up a tube that needed 1.6 amps. OK. Fine. I decided to move on to constructing my base.

Fail Number Two.

The hole saw I’d bought had a different size shank mounting hole than the shank I had. Sigh. Enter the memory that the set of hole saws I had was bought at Lowes in Orlando, and were a different brand than the one I just bought at Home Depot, despite being the same color. Since the closest Lowes to Key West is at the very least much farther than I’m willing to travel on my bike, I decided I’d just buy a new shank and get it over with next time I was at Home Depot (Which as it turns out was much sooner than I expected).

I decided to just build the wood part of the base and deal with the rest of the stuff later. Except when I started trying to decide on the size of it all, I realized that if I needed a new, more powerful transformer, it was likely to be larger than the one I had in my grubby little hands. God DAMNIT!

Back to the trusty steed for another delightful 1-hour round trip to Home Depot and Radio Shack. Except this time I mixed myself a vodka tonic and stuffed that puppy in the drink-holder on the handlebars. That made the trip less tiresome. Luckily the weather was absolutely delightful, but then it usually is here.

Fail Number Three.

Back at home after the second trip to new town, I pulled out my newly-acquired, amped-up transformer and hooked the tube to it. Nothing. I could see the bottom of the heater filament glowing, but nothing impressive at all. All my plans for the vector amp began dissolving in front of my eyes at this point. I posited that tubes must need to be in a full-on circuit and under load to really put off a nice rosy glow, and that just hooking the heaters up didn’t cut it at all. Fuck Fuck Fuck.

OK, breathe…

I put all that failure behind me and decided to go back to working on the base now that I had the proper hole-saw shank. I got out my 3/16″ sheet of copper plate that I had lying around and scribed out a 3″ square for my top plate. Now last time I had to cut this stuff I had a radial-arm saw and a metal saw blade. I left all that stuff back up in Orlando though, so I decided to try my hand at cutting it with a jig-saw.

I clamped a piece of wood to the sheet for a straight-edge and began cutting. After about 20 minutes I had gotten through about 4 inches. This was going to take all day! Then I remembered something. I had taken shop class back in High School and I remembered something about using oil to help while cutting metal.. Hmm. Enter a can of WD-40. Woah! I zipped through the rest of the 12″ of that plate in about 5 minutes.. definitely faster!

All in all it was a pretty straight cut.. which actually surprised me. It wasn’t nearly as nice as the cuts I’d gotten with my radial arm saw, but beggars can’t be choosers I suppose, and with a decent amount of file-work, the edge could be made to be nice.

On to the drill press!

Springing back after successfully cutting through the copper sheet, I decided to go for the gusto and drill my tube-socket hole. I wanted a ring of 1/4″ holes around the socket hole to allow air to flow up through the base and help keep the tube cool. In addition to being functional, this looks really cool in all the home made tube amps I’ve seen out there. So I scribed out my lines, and used a punch to dimple the surface where the holes would go.

Fail Number Four.

I clamped the metal down on a scrap of wood and started drilling. Right away I knew I was in for a long, tedious, and possibly ruinous process. I used a ton of wd-40 to lube it up while cutting and still it took the better part of 20 minutes to get through the plate. I was using a 1-1/8″ bi-metal hole saw, and it worked.. to a point. The hole turned out being about 1-1/4″ due to the wobbling of the tall saw. Definitely NOT aerospace quality construction, but at least it worked.. the hole was round and straight. Unfortunately however, the increased diameter of the hole meant my tube socket plowed right through the hole instead of butting up to the underside. Sigh. Back to the drawing board.

This was most definitely not a process I want to repeat, and I have decided that for future projects I am buying sheet metal hole punches for making holes. Screw trying to get through sheet metal with a hole saw. The noise and vibration alone are enough to turn me off of the technique, but combine those with the inaccuracy of the hole size, and it’s a deal killer. Hole punches only work up to about 10 guage metal however, so I won’t be able to use the 3/16″ plate I have, but I can get 1/8″ copper sheet readily (if not cheaply) on the internet.

So in Closing Let Me Just Say This…

AAAARRRRGGGGHHHHH!!!!!

There was some drinking going on after this day to be sure. One step forward and two steps back seems to be the lesson learned. I’m not giving up though. I guess I’m going to have to break down and actually build that tube amp for the Vector Amp project after all. Hey, it’s only money right?

M

The Vector Amp

 

I actually built this box some time ago for another piece and never used it. It’s perfect for this project though. The wood is 3/4″ white oak that I scavanged from an old bookshelf I got back when I was in High School (That’s old). The lens on the front is an old Bell and Howell camera lens from some sort of arcane camera. If I had to guess I’d say it was from an old aerial photography camera. My Friend Jeff League was kind enough to hand it it off to me one day because he thought I could do something cool with it. Let’s see about that!

The front optic is 4″, and the rear is 2″ which is perfect because I plan on placing a small LCD screen inside (3.5″). The LCD screen will overlap the back optic just enough to give me a full circle of view from the front. I dug around on the internet quite a bit looking for small LCD displays. I would have thought that they’d be abundantly available these days, but it seems the trend of bigger-better-faster-more is overtaking LCD tech and it’s difficult finding them below 7″. I was however able to find a back-up camera kit for an automobile that had a small camera and a 3.5″ screen that runs about 100 bucks that will work out perfect. The camera I won’t need for this project, but the next piece I have planned will make good use of it!

For the video and audio playback I turned to the wonderful world of digital signage. I needed a solid-state device that would play a digital video file (.avi) on a loop when powered on, and stay playing without needing any button-pressing. There are quite a few very fancy units out there that will do just that and much more. Unfortunately most of them ranged in the 400 dollar and up category. Far too much for my meager budget. I finally, after about a month of fruitless search, was able to find a unit for 150 bucks that was just perfect. No HDMI, no multiple outputs, no ethernet linking, etc, etc, ad-nauseum. It seems these days that since something CAN be done, we feel it must be done.. in my search to find small, simple, inexpensive devices I realized that it’s getting harder and harder to find things like that. Everything must be all things to all people. I’m not sure I like this trend! Anyways, I digress. Back to the story. Alternately I suppose I could use any number of the digital picture frames out there that play video and audio. I’ll probably do some research into that and make that decision before jumping off in any one direction.

For the Audio amp side I was originally going to use a bona-fide tube amplifier kit from Tube-Depot. However, after a month of reading books on tube-amp design and electronics theory (my head hurts), I came to the conclusion that any tubes I could use in an inexpensive tube-amp would be far too small and more to the point, uncool looking for the top of this box. Tube amps are all about the marriage of a electron tubes to suitable transformers, and as most things go.. the bigger and more cool-looking your tubes are, the bigger (and more expensive) your transformers have to be. Now, while tubes are somewhat inexpensive (15 to 100 bucks on avg.), transformers for big, cool-looking tubes run in the multiple hundreds of dollars range.

It seemed silly to drop 600 dollars on a tube amp that was just going to be used to play some ambient audio from 3″ speakers on a loop. So I stepped back from the kool-aid.. I would buy the big, cool tubes, and just wire them up to glow. This way I can chose tubes based solely on their aesthetics. This of course means now I needed to have some other small, solid-state amp to power the speakers with. Enter Parts Express! For 30 bucks they have a small kit that runs off a simple transformer, and will power those 3″ speakers without any problem at all. Have I ever extolled the virtues of Parts Express? Man I love that place. The catalog is like Playboy to me.. I read it endlessly.

The speakers will just be some 3″ full range jobbies from parts express. The don’t need to be anything fancy or cool looking since they will be hidden in the 4″ copper tubes, they just need to work.

The copper elbows I found online. 4″ copper elbows are NOT cheap (Remind me again why I decided to work in copper?) they run about 60.00 each. I’ll need 4 of them for this project, as well as a foot or so of 4″ copper pipe which runs 65.00/foot. All in all the copper pipe will be the most expensive aspect of this piece. But I think it’s absolutely the most important as well. PVC pipe painted to look like copper would be.. well.. unsuitable at best.

So anyways, I have all my ducks lined up. The plan is set, and some of the parts are already on their way to me, so I’m off and running! I’ll post back soon when I have something interesting to look at!

M