RHYTHM MACHINE FINISHED...

well its been a long week. after spending about 14 hours putting all the circuitry together on friday, i took a 3 day break for my day job. it was quite the wait. i thought that if the circuits all went to plan, i would have a new keyboard by friday night, but naturally some things didnt work. in a nutshell, the filter/amplifier module was wrong(i still dont understand why), i drew up the keyboard's schematic wrong in some places(three times), and some of the lfo mods that i didnt breadboard first didnt work at all. i put in a few hours before and after work over the weekend, but it wasn't until today that i wrapped this project up. i rebuilt the amplifier/vcf module and fixed the errors i had made with the schematic. i put it all on bread board before i built the module again. it was exactly the same as the first one. i still dont understand why the first one didnt work. the second lfo that was supposed to modulate the pitch bend didnt go deep enough and raised the minimum pitch too much to have a coarse and fine pitch bend. instead i sent the square output to the vcf so now you can modulate it with either ramp or/and square. i also got rid of the feedback function and used the pot to cap the depth of the square vcf mod. there was some bad buzzing coming from this keyboard. i knew it was there the whole time. thats just the price you pay when combining toys and single supply vcf's, but when i put it back together it was much louder. i went back in and found that the filter/amp section needed to be further away from the keypad. i had to UNGLUE it! i hate ungluing! i pulled it away and wrapped it in electrical tape(not sure if that does anything) and now the sound is as faint if not more so than when i prototyped the circuit. there are still some things i have to fix though. the lfo pots that trigger the cowbell and bass drum also control the vcf modulation. the switches that turn the triggers on and off are supposed to be right next to their respective knobs, but for some reason the switch for the bass drum is next to the cowbell pot and viceversa. also the square signal that is modulating the vcf is a little too strong. you can hear an annoying click when you turn the speed up. i also need to fix the 1/4" line out. it sounded kind of squirly when i hooked it up to my computer. i'm sure its an easy fix. here are some pictures of the assembly.


the video is pretty uninformative because my camera ran out of batteries and space. i hope its audible.

RHYTHM MACHINE

i started this project a week ago today. i was thinking of doing up another mini glitch keyboard but i wanted some better rhythms. i found this old barbie keyboard laying around that had some pretty nice semi analog drum beats. i broke it all down and found that the keyboard could in fact run off of 3 volts, but in the process of deconstructing the circuit i found a bunch of hidden voices, rhythms, and functions that were too cool to leave out of the project. in order to fully utilize all of these functions, i would need a lot of switches and pots, and there wasnt enough surface area on the mini keyboard. instead i used this little baby organ toy that i had laying around. it to only held two AA batteries, but the battery door was big enough to fit 3 AAA's after a little modding. the thing that i really found interesting about this circuit is that not only are there two outputs from the chip for keyboard tones and rhythms, but there is a third output that is soldered directly to the rhythm output. after disconnecting them, i found that the snare and hat sounds are on a separate channel that the bass drum and cowbell. i really could have gone very minimal with this project and just made it in to a drum cube or something, but i decided to go all out this time. basically i designed my own functional interface with all the new easteregggs i found, added a volume mixer pot between the two drum signals, added two pots to slightly change the rhythm output envelopes, pitch bends(fine and coarse), replace the transistor r/c amplifier circuit with a 386 with adjustable gain and feedback, added a vcf to the keyboard tones, added 4 separate lfo's to trigger each drum sound with adjustable frequency and on/off switches, and made it possible to switch the cowbell and bass drum lfo to modulate the vcf and pitch bend respectively, with or without triggering those drum sounds. the function switches are set up like this; since there was not enough room(or time in the world) to cut and put in 27 momentary switches, i just put in 11. one is to turn the power on and off, two others are for increasing or decreasing the tempo only, the other 8 are hooked up to a three position switch that is also hook up to a tri-colored LED. in one position the buttons will select rhythms, in the second voices, and in the third functions like rec/playback, rhythm start/stop, etc. in each of the three positions the LED will glow in a different color, red green or blue. what else... oh yeah, since i decided to only use one octaves worth of keys, there is a transpose switch that moves the keyboard up one octave. so far thats it. now i just have to decide on colors. more to come. here are some pics so far.

deconstruction notes


revised notes and schematics


breadboard(it works!)


that blob in the middle is all i need


side profile


parts



tape up

NEW GLITCH KEYBOARD

this keyboard is much like the last one. it basically consists of a keyboard circuit, drum circuit and glitch circuit. this one however is considerably smaller and doesnt have any signal modulation like the last one did. the reason for that is that it was all too confusing. with this new revision, the glitch circuit is very basic, it has a "beep-beep" horn sound switch, a glitch switch, and a reset switch. oh yeah, and a pitch bend. the keyboard circuit in this one is completely different than the others i've done in the past. i took the main chip out of a toy keyboard from the junk pile that played 8 notes and 5 different keyboard sounds. you can choose between piano, dog, cat, frog, or duck. i also added a switch to sync the key-play to the drum machine.
to build, this keyboard was quite the pain in the ass. painting it was a disaster. after a day of cutting, sanding, and gluing the keyboard's body to the way i wanted it, i primed it and let it dry. after a couple days of drying, i painted it with my airbrush. the keys came out nice but the keyboard chasis was a different story. i painted it all red and then painted a really sweet yellow hexagonal pattern over that. it was a great idea and i'll probably use it again someday, but this time it didnt work out. the paint was too heavy and bled under the masking, and the red paind wasnt dry enough so it peeled in place when the masking was removed. i decided to soak it all for a couple of hours and try to scrub off all of the acrylic paint. after 3 hours of getting most of the paint off, i decided to just paint it all orange with krylon fusion. i took it outside and painted one piece and noticed that almost instantly the krylon was disolving the white primer underneath and making big bubbly scales out of it all. at this point i knew i was screwed. i continued painting the rest of the keyboard orange, and with a pair of rubber gloves on i started intentionally smearing the paint arround making big blurs and textures in the paint. i then took it inside and applied some left over hexagon stickers and airbrushed a blak fade overit all. it looked pretty cool in the end. if the colors werent so flat the textures so terrible, i probably would have used it. but i didnt. instead i wallowed for about an hour and went back to my shop and started over from scratch. it only took about an hour and a half to do the second one. i was able to sand and paint it all that night.
yesterday i wired it all up. it took ALL FUCKING DAY. i went out for drinks from 9-11pm and then finished it at about midnight. the hardest part was getting everthing to fit in there when it was closed back up. hopefully this thing will never have to be reopened.