Mike was also kind enough to answer a few questions about his devices.
CM: How did you manage to make the APC do what appears to be fairly set note intervals? Did you mod the circuit at all?
Mike Ford: I had tried the 556 schematic to no avail and had to go with a dual 555 set up. The circuit has been modded to include two rotary switches with various caps, sorta a range setting, I suppose. The other mods are two photocells that act as Pitch and interval. I plan on adding the Vox repeat percussion circuit in the future.
CM:The Nemo beat box is fucking rad! Are you getting those extra sounds through some feedback circuitry?
MF: NEMO is a bent 1980s Realistic/Radioshack beatbox. I kinda love those old drum machine sounds and hope to get a National Panasonic or Univox to mangle (circuitbend) soon! There were some trimmer caps on the board I wired some pots to gain control over the oscillators that were set from the factory.
CM: How are you managing to keep contact capacitance from influencing the circuits with all that metal?
MF: Oops. didn’t consider that!
CM: Lastly, have you ever built a really nice case only to realize that it was not worthy of the sound generator?
MF: Sure. I usually work out the ideas in parallel. Or, that is to say, sometimes things will develop simultaneously. Sometimes stuff sits around collecting dust till the inspiration comes or I am driven to finish something and get on with another project. I think I am about to turn a corner and start to actually perform with the works. After all, my intent was to build stuff I would want to use in a performance setting.
CM: Thanks Mike, we’re looking forward to new and exciting performances as well as devices.
The ever controversial craftsmen of very nice looking Folktek instruments are putting on some sort of a competition via an eBay auction. The premise is that after buying a mystery sound circuit for $44.44 you will be entered into a competition to create a sound art piece with that circuit. The best entry will receive a custom Folktek instrument. Deadline for submission is August 30th and the winner will be chosen and made example of by last day in September. Any takers?
In the previous post we established what a Dub Siren was. Now it is time to make one and start the journey to become a Legendary Dub All-Star.
First you need the parts:
8 Sound Keychain – available here in packages of 12 for $9.50 plus shipping! There is plenty of other sound generating circuits out there which are cheap and in the next few days I will do a keychain roundup. There is also a COB (Chip-on-board ) version of this sound generator without the button traces that would be a lot easier to work with. This particular keychain just sounds so good, its got your sirens and machineguns, which everyone instantly recognizes as being Atari like or 8-bit, plus it loops!
Rotary Switch – this will be the sound selector. 8 position is ideal, however 12 position ones seem to be most common and are the cheapest from Jameco. This is what all the sound buttons will be wired to and the center pin will be going to a push button that will trigger the sound by completing the circuit with the Ground.
1 Mega Ohm Linear Potentiometer – to control the pitch of the sound being played back. Obviously the sound circuit has to have a pitch resistor, most cheap keychains do. Lets try to stick with just Jameco for the source.
2 Momentary Push Button Switches – One button will connect the ground to the rotary switch and the other one will be used as a Mute by sending positive output from the instrument jack to the ground. Jameco once again.
Rubber feet – so the Rasta Box doesn’t slide off that table when the Bass is bumping.
Solid Core wire – stranded core will be a pain to work with, it splinters too easy.
The total for parts should be under $20 and possibly even cheaper if you are resourceful and can strip components from discarded electronics, etc.
The construction process: Get everything together in one place on a work surface in a well lit and properly ventilated environment.
1. Connect the battery compartment to the 8 sound keychain board. ( Probably best to keep the batteries out for now, so there are no shorts ) No need for power switch because this particular keychain powers down automatically and instantly comes ON when the any button is pressed.
2. Solder the output jack to where the speaker was connected on the sound board. One wire to the Transistor Buffer and the other to the positive terminal? I dunno seems like that’s how they had it. Normally you would connect the Ground to the outside ring of the instrument jack and the Positive output to the tip.
3. Remove the pitch resistor and replace it with a 1M potentiometer. Center and one of the outer taps should go to where the resistor legs used to be. Very important, connect the remaining outside tap to Ground, this will give you the low pitch drop!
4. This step is perhaps the most tricky and easy to mess up, solder 8 wires to the button connection traces. These are very thin traces that interlock and if you build a solder bridge the sound will be stuck in the ON position. It will be hard and the only thing I can recommend is that you lightly sand or scrape the green protective layer and possibly cut the traces that go to Ground from those buttons. Solder with caution and be careful not to pull hard on the wire because the entire trace may come off. At this point you can probably plug in the batteries and test the soldering job making sure that if you connect the Ground to any of the button wires the sound gets produced. If the soldering checks out, drench that thing in hot glue so nothing moves or falls off!
5. Take a break then drill some holes for the controls in your plastic box. Make sure the knobs are spaced such that there plenty of room for them to rotate. After that you should overlay the graphic and then cut the holes on paper for the controls to slide through. To hold the paper in place I just use packing tape, but there are other plastic sheets and laminate options if you want to get fancy with it.
6. Mount the push buttons, the potentiometer, and the rotary switch in the case if it is big enough to work inside. Otherwise solder wires to the components first and then mount them. Please note that there will be more solder lugs on the rotary than button contacts. I typically just use every other one the first round. The trigger button needs to have a wire going from the center tap of the rotary switch to one of its legs. The other leg needs to be connected to Ground. The Mute button will need to be connected to the tip of the output jack with the second leg going to Ground as well. The potentiometer should just have to be wired to the ground. If you are clever you can make all the Ground connections meet at the same place saving on wire. Mount the output jack and test everything. Makes sound? No…try setting the potentiometer to center and maybe resetting the batteries. Still no? Go back and recheck your connections.
7. If everything works, use copious amounts of hot glue to hold stuff in place. Close the enclosure and start jamming out. The gate switch should chop up the sound when pressed, doesn’t get much simpler than that.
Next plug this into a delay pedal, turn up some Dub Reggae on YouTube, and start Toasting! The only thing to watch out for is overusing these sounds because they eventually lose the magic. However the first 30 minutes will be a pure blast! Enjoy.
P.S. Here is the rough schematic of the circuit with the keychain board in the center, note the red Xs, those are to indicate that if you are soldering to the pads make sure they are not connected to any other pads via Ground. I can post a picture of exactly what I’m talking about soon.
* Updated *
I will be making another schematic and a new version of the siren using the Chip-on-board sound circuit. Also if these keychains are not available in your area, for whatever reason, feel free to order them from GetLoFi here.
At about the 40 second mark of this video you can hear a Dub Siren aka Rasta Box. They are simple electronic sound effect units used as musical accent in Dub Reggae. The sounds are typically simulated police or car sirens with pitch control and the ability to only trigger the sound when the button is pressed. For the most part that is the fundamental difference over devices like the Atari Punk Console or other Opto Theremins that produce similar sounds but generally have no Envelope control besides volume. Dub Sirens like much of Reggae are drenched in Delay, lots and lots of Delay! Recently, at least to me, it seems that Dub Sirens made a crossover into the Circuit Bending and Synth DIY scene. Consider these fine examples: Video 1, Video 2, Video 3.
Video of the system in action and an audio sample of the above device with just the noises. Whats interesting to note is that the Pitch is set via a rotary switch and not just a potentiometer. In a way that seems like it would be easier on the ears, no jumping around in frequencies. Another commercially available unit is from Theremin Planet for 130 Euros! I guess what I’m trying to say is that most of these Dub Sirens are simple dual 555 oscillators with a trigger button and Rasta colors.
A CMOS Version of a Dub Siren is available on the AEE projectblog. However most of these require building relatively complicated oscillator circuits, but fear not because shortly I will be posting a “How To” on making a Dub Siren using an 8 Sound Keychain. Jah Mon!
P.S. Looks like my Embedded YouTube videos are not working for some reason. Atleast on Firefox 3.
Tony of Electrokraft has just released a set of new products: Super Synth Drums the DrumAxe. Both work in conjunction with an NES system running custom software called Super Synth Drums. The software translates button presses into Drum sounds that are being synthesized by the NES itself. Everything was written in 6502 assembly language and burned to a ROM by Tony. His main resources for learning ASM were books like “Atari Roots” by Mark Andrews and others written in the early 1980’s, as well as help from people at the NESDev.com website.
In the heart of the circuit is a PIC microcontroller driving a 4021 “parallel to serial” shift register. Multiple input buttons or in this case touch sensors are encoded to single serial output that is understood by the Nintendo System. The Sonic DrumAxe essentially replaces gamepad #1 on the NES. The second gamepad can be used to add a variety of pulsing/looping effects. Unfortunately given the current legacy status of the NES hardware, the actual NES connectors are hard to come by without cannibalizing and existing system, so Tony devised an RCA style setup with an OEM DIN to RCA cable. 4 RCA jacks on the NES correspond to the Clock, Latch, DATA, and Ground required for sending bytes to the NES CPU.
There will be an upcoming tutorial demonstrating how the Sonic Drum Axe’s circuit was made and how it’s connected to the NES. Also for those who have already purchased the Super Synth Cart or are thinking about it, please keep in mind that in the future Electrokraft may offer free ROM upgrades, which will include more sounds and features! Harmony Central just did a wrote up as well.