I have known for a while now that once I finished The Mole, I would begin working on A Weird Sound Generator. I had found the schematic when I was looking for projects to make with the ICs that I had on-hand, and it seemed like a fun project. The nice thing is that I could concentrate more on the superficial stuff (crazy case and controls), rather than the actual schematic and electronics behind the project.
I ordered the parts for this back in February, when I ordered parts for the Triggered Drum Light, but since I only have one breadboard, it was going to be a bit until I could get to it. Until then, I decided I was just going to keep my eyes open for weird and unusual parts that I could slap onto this thing.
I knew that the schematic called for several 1MOhm potentiometers, and one day when I was in Ax-Man, I spotted these groovy pots that were in enclosures and wired up to RCA jacks. I figured these would be perfect as the main controls for this project.
Now I just needed a box to house everything.
While I was in Florida on vacation, me and the wife went to several Flea Markets, and it was in the last one we visited, in Saint Augustine, FL, that I found the box I was looking for. It was an old case for testing T1 lines, made by Western Electric, the hardware manufacturing arm of Ma Bell. I dickered with the guy selling it (he wanted $20) and bought it for $5.
This is certainly going to be an interesting project.
Since it has been a while since I put anything on the breadboard, I figured it wouldn’t hurt to start working on the T1 Corruption. I found some time, and started tossing parts onto the board. I was working off of this schematic for the “Weird Sound Generator”, and unfortunately I wasn’t totally familiar with this style of schematic, but I worked through it, until I had something that seemed accurate.
I had to solder up the potentiometers, since none of them were using the third terminal. Fortunately for me, all of them double back on themselves to the middle terminal, so it was a simple soldering job. However, when I turned the unit on, I got sound, but half of the potentiometers didn’t work, and it just didn’t sound like the samples I had seen on-line. Since I had already been working on this for a while, I decided to set it aside and come back to it at a later point.
So a few days passed and I started troubleshooting. After making sure none of the component’s leads were touching each other creating a short, I started comparing my layout to the schematic, and realized that A) my diode was reversed and B) a couple of my pots were wired to the board in reverse. I fixed these, and power the thing on. I had sound!
So the next step will be getting this on a PCB and figuring out how I’m going to stuff this into the old T1 Test unit.
It was high time I took a break from working on the Gauntlet machine, so I decided to put forth some effort to finishing up the T1 Corruption.
This has been the most complex circuit I’ve worked with (as far as number of components and number of external controls (Pots & switches), so using Visio, I began to map out how I was going to lay this thing out on a PCB I picked up from Rat Shack (Part No. 276-150, the same board I used for the Triggered Drum Light).
I probably spent two or three hours mapping out how I wanted to lay things out, trying to leave room in case I wanted to piggy back some LEDs onto the board (there are standoffs built into the faceplate of the enclosure I bought for this project, and they are perfectly spaced to fit the pre-drilled holes on the PCB. The board would then sit right in front of the old 7-segment LED window. Putting a few LEDs on the board, I could then make a logo up and have a little backlit nameplate, or at least that’s the idea). Overall I was happy with how things turned out:
As you can see, there is a lot going on here. It wasn’t going to be a quick project to solder up, nevermind the fact that I was manufacturing my own cables to run from the faceplate to the control boxes (that I bought from Ax-Man).
I ended up starting with the cables. They were going to be about a foot and a half long, with a 1/4″ phono jack on one end (to go into the faceplate), and an RCA jack on the other end (to go into the controller). I started soldering them up, but quickly realized that the shrink tubing I had bought (on-line) was too narrow to fit the two wires I had soldered up. Luckily I knew a place locally that sold shrink tubing in longer lengths, and while it probably took me an hour of cutting wire, stripping wire, soldering screwing on connectors and shrinking the tubing, they ended up turning out pretty nice.
I was able to hook them up to my breadboard, and surprisingly they all worked like a charm.
Within the next few days I figured I’d get started in transferring the parts to the PCB. This was not an easy process. With over 100 solder points, I was going to be at this for a while.
Over two nights and probably four hours of soldering, I finally finished with the soldering. I hooked everything up, including the new switches I had bought a day or two prior, and it wasn’t working. ICs were there, so I hadn’t made that mistake twice. Everything looked solid, no components were loose. The only thing left I could think of was the soldering.
I started to check each solder point, making sure nothing was loose, and nothing was shorting. quickly I found two spots where the leg from a component or a wire was too far over, and probably shorting. These were kind of long as it is, so I took out the clippers and nipped off the long shorting ends. Fired it up, and now I was getting sound!
Unfortunately, some of the controls were not working, particularly the two components that were hooked up to the switches, the killswitch and one of the tone knobs. I had already put in enough time that night, so I called it a day, knowing that was the next thing on my plate.
Today I picked up the PCB, after letting it sit for a day, and started troubleshooting. Using the continuity setting on my multimeter, I went looking for shorts on or near the switches, and couldn’t find any. Switches seemed to be working fine, so I couldn’t figure out what was the problem. So I snipped the wires on the switches and using some jumpers, hooked up a switch I had been working with on this project prior to finding these new switches. And….
“Great”, now the switch that was working, no longer was working. It didn’t take long to figure out why. One of the wires had wiggled loose from it’s solder point. Soldered it back up, and the switch worked perfectly. Resoldered the snipped wires back to the existing switch, and went to work on the other switch (to activate the killswitch).
This one was acting as if it was always on, regardless of what position I had it in. In the off position, the signal should be routed to the Out Jack, and in the on position, the signal should be routed to the killswitch and then to the Out Jack. A simple SPDT switch setup. Hooking up my multimeter, the continuity was acting just like I thought it should, but it wasn’t working right when I had everything running. I snipped the wires on this one, and used three jumpers, and started playing around how they were hooked up to the switch.
It turns out that this switch is just funky (or at least I’m not familiar with). Basically the switch will send signal to one out pin, or both out pins, depending on the position. So I would need the “always on” pin to be to the killswitch, and the “part on” pin to be wired directly to the out. This was as easy as flipping the outputs around.
I soldered everything back up. Powered it on, and bingo, everything is working! Short of the case and running power, this project is getting really close to done. I enlarged a few of the existing holes on the faceplate and started mounting up the jacks, switches and pots.
It’s looking really sharp. Next step is working on the lighting that I’m going to install in this box!
P.S. – I’ve also decided on a name for this project. From here on out, it will be the T1 Corruption, in homage to it’s humble beginnings as a T1 Test Unit.
With the audio portion of the T1 Corruption pretty much done, I decided I wanted get some LEDs in this thing and make it “sparkle”. The first, and easy thing to do was put a bunch of spare 3mm LEDs I had onto the sound board, with the intent of using these to backlight the logo in a area on the panel where the old 7-segment LED readout used to be. This was fairly simple, as I tossed 6 LEDs on with accompanying resistors and it lit up the panel, without a problem. I’ve got a logo done, I just need to figure out a way for the panel to stay there and not flop out, but I figure I’ll tackle that issue later.
Next step in lighting this thing up is to fit some LEDs in where the old indicator LEDs used to be. However, I didn’t want them to be just static. After talking with a buddy about his electronics projects, I decided I would appropriate his project for use in my WSG. Conveniently, his project was a K.I.T.T. styled LED tracer. I’m not sure where he found the schematic, or if he designed something on his own, but I found a schematic that worked for me, and began breadboarding it.
The biggest obstacle for me was going to be figuring out how to step the power down from 9V to 6V, as I wanted to run everything (the lights and the sound) off of the same battery. I dug around on-line, and found a schematic to regulate the voltage down to 6V (I can’t find the original source I was looking for, but it’s similar to the one found on this page), and luckily I had the IC needed to make it happen.
It worked just as I had hoped!
However, there was a dilemma. The two LED banks on the existing box were a set of 8 LEDs and a set of 7 LEDs. The K.I.T.T. schematic I found was only 6 LEDs. I figured I could try and double one or two of the LEDs and see if that would work (and not kill the circuit). I tried one, and it worked fine. I would have used a center one, but since there are two center LEDs, I opted to double the first LED and the last LED, to minimize the obviousness of my duplication. It worked swimingly!
However, there was still the matter of what I was going to do with the second bank of LEDs. After some hemming and hawing, I decided to wire up seven more LEDs, meaning half of the 6 original LED spots would be driving 3 LEDs and half would be driving 2 LEDs. I would take the additional 7 LEDs and arrange them in a random order, with two of them firing simultaneously (much like the K.I.T.T. layout). I figured this would emulate the futuristic computers from 60s and 70s TV & Film, which would have been about when this T1 Test Unit was originally made.
I wired everything up (using Euro-style screw terminals, to allow me to easily randomize the order of the LEDs, without having to plug and unplug them from the breadboard) and it worked just as expected. For a short while I toyed with the idea of hooking in a second set of controlling components to allow for the futuristic lights to be driven at a different speed (the speed can be adjusted by adding an additional resistor (up to 47k total resistance) on the 22k resistor (that is not hooked to the 1N4148)), but decided against that as it would mean I would probably need a third PCB in the enclosure, and I was already running low on space. I will say though, it did look cool at a super fast speed!
With these steps done I will be adding 21 LEDs to this box. My Weird Sound Generator is not only going to sound awesome, it’s going to LOOK awesome. Now I just need to get it soldered up, and this project will be pretty much done!
As of my last post, I pretty much had everything done, I just needed to get everything mounted inside the case, and a few minor tweaks here and there.
First thing I did was wrap the power leads running to the sound portion of the box, to the lighting portion, so that both boards could be run from the same power source. All of the components in this project do not use a ton of power, so piggybacking them was not a concern of mine.
Secondly, I needed to prepare the logo to be mounted into the old space where the 7 segment LED readout used to be. I decided I was going to superglue the red plexiglass into the holder, and use a piece of transparency paper with the logo printed on one side, and the other side lightly sanded, to act as a diffuser.
Preparing the logo transparency was pretty easy, but if I had thought it out a little more, I would have sanded the transparency first, and then cut the logo out (sanding a tiny little square of paper-thin plastic is difficult, to say the least).
The superglue didn’t work out nearly as well as I had hoped, but it looks good enough, and most people wouldn’t even notice the problem I had. For some reason, the superglue, even when applied sparingly along the edge of the plexiglass, caused a portion of the plexi to “haze up”. I could scratch part of the haze away with a fingernail, but I didn’t want go crazy, as I didn’t want to have to replace the plexi.
Next step was mounting the 15 LEDs that I had used on the old status indicators. At first I thought I might be able to reuse the old LEDs that were previously housed in the box, but regardless of what I did, I couldn’t get any of them to light up (I had no data sheets on them, so I had no clue as to what voltage they required nor what sort of resistors were needed. Perhaps 6V wasn’t enough). So I had to mount each LED in place, and I started by soldering up the anodes of the LEDs and then daisy-chaining the cathodes together using the lead that was on each LED. The leads were rigid enough to also help support the LED chain, and the rigidity kept the LEDs in place with no further support (there was a small backerboard on the display, but not enough to keep a dozen-plus individual LEDs in place).
After getting all of the lighting in place, I needed to permanently house the battery compartment. There was already a hole in the built-in cable holder on the enclosure, but it was just a bit too small for the compartment. Using a dremel, I cut away four corners of the hole, and the battery compartment was able to slide right in.
The last step was mounting the circuit boards. The sound board was easy to mount, because the enclosure already had standoffs from the previous board, and they just happened to match up with the mounting holes on the new board. As for the lighting board, I had to get creative.
There were no additional standoffs, and space inside the enclosure was running scarce. So I opted to mount the board to the side of the inner enclosure, using double-sided foamy tape (non-conductive). It’s a little less permanent feeling, but hell, I’m the only one who is ever going to know… Right?!
I put everything back together, put the knobs on, tighten the set screws, and I’m done. Powered the bad-boy on, and enjoy the chaotic noise emanating from the T1 Corruption.
|1 14 PIN IC Socket||$0.20|
|5 RCA Jacks||$2.00|
|1 100K Potentiometer (linear taper)||$0.75|
|2 SPST Switches||$3.90|
|1 .1 uF Ceramic Capacitor||$0.05|
|2 1uF Ceramic Capacitors||$0.50|
|2 .022 uF Ceramic Capacitors||$0.38|
|2 470 pF Ceramic Capacitors||$0.38|
|1 2N3904 IC||$0.15|
|1 Diode: 1N914 or 1N4148||$0.03|
|1 LM741 OpAmp (or equiv)||$0.39|
|1 CD40106 (CMOS only, not 74HC)||$0.76|
|1 Battery Holder||$4.31|
|1 T1 Data Test Set (Enclosure)||$5.00|
|5 Oddball enclosures with RCA Jack and 1 Meg Ohm Pots||$7.50|
|1 Heatshrink Tubing||$1.99|
|2 Radio Shack 276-150 PC Boards||$3.98|
|5 1/4″ Phono Plugs||$9.95|
|1 Various Resistors||$1.00|
|1 Various Lengths of Wire||$1.00|
|5 Right Angle RCA adapters||$6.25|
|6 1/4″ Phono Jacks||$1.98|
|20 Various Red LEDs||$3.00|
Some of these I had on hand, and those prices are just estimates. Total cost of the project without all of the gratuitous fluff (LEDs, external controllers, etc.) is probably closer to like $10. I suggest everyone should take some time and put one together. They’re damn fun.