Modding Gakken's Otona no Kagaku Kits


10/06/14: Added entry for the Pocket Miku, USB camera, Auto Writer and Steel Drum.


The Gakken Adult Science kit series is geared towards making modifications to each of the kits. It's not like you open the box, screw a couple of pieces of plastic together and then place the kit on a shelf for everyone to admire how pretty and elegant it is. No, you're encouraged to break out the drill and glue gun in an effort to void the warranty and eliminate any possible resale collector's value the kit might have had.

The mooks list customizations that the authors have dreamed up, and even include instructions for how to make the mods. What I haven't seen yet are many follow-up articles showing original ideas from the readers. But, if you search the net, there are youtube videos and the like from people such as the editors of Make magazine that have built such kits and critiqued them. Most of the reader mods have been to the synthesizer. If I come up with anything interesting myself, I'll send in photos to Gakken and see what happens.

The kits from the Adult Science mook series fall into 2 categories (I've built all but five of them, since those 5 are out of print and are looking harder to track down all the time.) That is, the battery-powered-kits, and the non-battery powered ones. All of the battery-powered kits were begging to have power adapter jacks added. The following is a list of kits and what I've done with them (if anything).

The full list of kits, plus links to Gakken's online magazines, and the reviews on ThreeStepsOverJapan, can be found in the Gakken Kits List.

Modded Kits:

1) Putt Putt Boat
I tried the "whiskey and salt" candle with no effect. The alcohol burns off too fast. Standard candles make better power sources. Otherwise, no mods.

2) Spy Kit
Not a lot to do with this kit normally, much less for modding it. I stole the polarized blue LED for use with the phonograph kit. Otherwise, no mods.

6) Edison-style Phonograph
The phonograph was hard to deal with. It uses a 1.5 V motor for the turn table, and the motor speed is directly related to the voltage applied. I can't find a 1.5 V adapter, and zener diodes only go down to 3V. My initial idea was to take a red LED with a 1.6 V drop and put it in parallel with the motor, while using a variable resistor to drop the remaining 1.4 V from the adapter, which would also let me tweak the current through both the motor and the LED. I didn't know exactly how much current the motor would draw, so I found a 5K pot. and wired it in series with a 20 ohm resistor. After spending 20 minutes boring 3 holes into the base of the phonograph with a small screwdriver blade, I wired everything up and nothing happened.

I troubleshot the circuit and found that the pot. connections weren't what I thought they'd be. I fixed the wiring, and still nothing. I pulled out the 20 ohm resistor and the motor then ran with just the pot, but apparently I managed to burn out the LED because it never lit up once. And, because even 20 ohms was too large for the resistor, using a 5 K pot. was also a mistake. Interestingly, the Spy Kit (kit #2) has a 3V LED and that works fine being connected straight to the DC adapter without needing additional resistance. So I swapped in the 3V polarized blue LED just to make the phonograph look more cool (and to have something to plug up the extra hole I'd made in the base). I then bought a smaller 100 ohm pot. in order to have more control over the motor speed. (The main reason for making the mod is that the phonograph goes through batteries in less time than it takes to play one 45 RPM record.) The 3V DC adapter ensures that the record speed will remain constant throughout the entire song, and the pot. lets me fine-tune the motor speed to match the record as needed. The LED just looks cool.

Next mod would be to add a different style speaker cone.

8) Slow Clock
This kit is fairly noisy, so I just use it as a small bookshelf. I used a soda bottle filled with water for the weight, and wrapped an ad for an anime DVD around the bottle for decoration. I also cut out a small box to put around the clock to dampen the sound (didn't work) and I put stuff on top of the box as a shelf.

9) Planetarium
Put in a power jack to run off a 3V DC power adapter. Had to reglue the panels together where the double-sided tape stopped holding. Otherwise, no mods.

10) Stirling Engine
Attached one of the spiral disks, that came with the mook, to the face of the engine. Turned the engine into a stand for holding the wind-up doll. Otherwise, no mods.

11) Newton-style Telescope
Created a pair of end caps out of paper to protect the lens and mirror from dust and smoke. Otherwise, no mods.

13) Kaleidoscope Projector
Added a power jack to run off a 3V DC power adapter. Tried using different strength light bulbs - and ended up adding (an intensely blindingly) strong 3V white LED. I've tried using clear plastic ballpoint pen cases to hold different kinds of sparklies (bits of colored wire insulation, glitter, etc.) but the resulting picture is mostly just white and gray.  Boring.

14) Stereo Pinhole Camera
Used staples on the picture viewer because the double-sided tape kept pulling loose and the lenses kept falling out. Chopped up the mook in order to look at the stereo pictures inside. Found a bolt that fit the mounting hole, and ran it through the plastic cap of a soda bottle to create a simple tripod.  No other mods.  I did get some good weather, so I went out and took photos.  On bright days, keep the exposure times down to 1-2 seconds to avoid overexposure on ISO 100 film.  To get a real stereo effect, you need to be within 5-15 feet of the subject, with the subject separated from the background or neighboring layers by another 5-15 feet.  If things are too far away, you lose the stereo effect.  The pictures are cool, but 35mm film is getting expensive to have developed at a store.

15) Reflective Movie Projector
Added a jack for a 3V DC adapter, and a strong 3V white LED to replace the original lamp bulb. Chopped up the book to create 6 rolls of "film" from the pre-printed movies. Used toothpicks for loading the film into the spools (instead of the original plastic pins, since the kit only supplied 4 pins and two are needed for each roll of film). Scanned all of the "film sheets" into my PC and turned them into tiny Flash .swf files (that is, the running movie is stamp-sized. The file sizes are several meg each.)  Created one original movie as a Flash animation that I printed out, cut up and turned into a paper film for the camera.  The result is ok, but it's too much work to do this more than once, given that I can get a better effect directly on the computer in Flash.

16) Wind-up Tea-Carrying Doll
Made the clothing out of origami paper, and added a hat made out of black construction paper. Turned the doll into a display piece and put it on the Stirling Engine.  The hat is being used to protect the Newtonian telescope eyepiece from dust.

17) Theremin
This kit has a lot of potential for mods. The Gakken mook suggests adding the grounding jack (first photo, right side), 3 photo resistors to control the volume level, and an audio out jack.  For the photo resistors, the mook says to use three 300 K ohm units.  I could only find 100 K ohm photo resistors, and even that seems excessive.  The problem is that even when exposed to bright light, the resistance level is so big that you can't hear anything from the speaker.  But, it is a good level if you have ear buds plugged in.  So I added a shorting switch below the audio out jack.  When I use the internal speaker (or when I plug into the SX-150 external source jack), I short the photo resistors.  With ear buds, I unshort them.  (Note, the photo resistors are in series with the internal speaker.)

The ever-present 6V DC adapter jack is shown in photo 2.  (I need to start labeling the jacks soon, or there's going to be sparks...)

The mook also suggests covering the case with cutesy little stickers, and to fold the antenna over and stick everything into a doggy doll suit.  Plus, the mook suggests using an old-style telescoping radio antenna in the place of the one that comes with the kit.  I'm not bothering with any of that.  However, I did plug the theremin into the source input jack of the SX-150 synth - sounded just like a theremin.  I.e. - no change in sound out.  Disappointing.

18) Wind-Powered Generator
This kit is a small AC motor connected to a 1.5V LED, attached to a propeller blade in a plastic housing.  This is good as a wind-powered nightlight, but little else.  The mook suggests playing with how you mount it to a fixture, using different-colored LEDs, or wiring it to the sound chip from one of those greeting cards that play music when you open them.  Given that you need a strong wind to get enough electricity to turn anything on, this kit is either going to sit on a railing outside, doing nothing, or be placed in front of an air conditioner or fan where you won't be able to see the LED (because it'll be facing the air conditioner and the air conditioner will be in the way).  No mods.

19) Galileo Telescope
Replaced the concave eye lens with the convex one to turn it from Galileo's design to Kepler's.  Used a soda bottle with the tripod mount. Otherwise, no mods. 

20) Bird Organ
Now here's a disappointing kit.  Essentially, it's just a small piston for driving air flow and an air channel directing the flow to a set of small whistles.  A sheet of paper is cranked across the air channel and holes in the paper dictate which whistle will play.  Problem is, if there's no hole in the paper, back-pressure from the piston (because of air build up) makes the crank really hard to turn.  And, leaks around the paper let the air out before it gets to the whistle.  The mook suggests replacing the piston with a regular bellows, but this kit isn't worth that level of effort.  I'll probably just throw this one away.  No mods made.

21) Magnetic Motor Car
Not a lot to do with this kit. I did attach blades to the wheel to turn it into a trill generator for the SX-150 synth. Otherwise, no mods.

22) Edo-era Spark Generator
The mook suggests a variety of attachments to the spark generator for trying different electrical experiments, such as a pendulum, a Franklin motor and a Leyden jar (two plastic cups wrapped in foil to store the charge ala a capacitor).  The problem is that the kit is very sensitive to environmental conditions.  Humidity, or oils inside the case can cause the charge to bleed off before a spark can form.  The Leyden jar does make the sparks stronger, but for the sparks to be bigger you need dry air and a perfectly clean case and roller.  The kit is good as a practical joke if you want to shock someone.  No other mods.

23) Poulsen Wire Recorder
The wire recorder is a really nice idea - take a cassette recorder record/playback head and connect it to an amplifier circuit. Throw in a toggle switch to connect either a microphone or a speaker.  You can now record your voice on any iron or steel surface, such as a knife, a bicycle spoke, or the side of an escalator.  Unfortunately, the amp's not very good and your voice will be garbled at the best of times.  The mook that comes with the kit suggests putting a longer wire on a spool, placing the head on a mounting arm over the wire, and replacing the speaker with a better amplifier and an external speaker.  I'm not bothering with all that - it's easier to just use an MP3 player for recording sound bites.

24) GMC-4 Microcomputer
The Gakken site shows a variety of suggested mods, such as a motor controller for their wind-up tea-carrying doll, an interface for an external signal generator to an SX-150 synthesizer and an interface to their EX-150 electronic blocks kit.  Someone else on youtube added a hex keypad over the plastic sheet pad.

Adding an external keypad is easy.  Peel the plastic sheeting away from the keypad area of the kit to expose the circuit paths.  Look for the solder points for each row and column and solder your wires there.  4 rows and 5 columns for 9 wires.  The paths are set up as a matrix and the kit interprets the key pressed by looking at which row is shorted to which column.  You can verify this by touching the row wires to the column wires one at a time.  Bring the wires to a 9-pin connector, then wire the matching connector to an external 20-pin hex pad.  Connect up the hex pad switches to mimic the rows and columns of the kit's keypad and you're done.

My mods are shown here.  First, I added a 15K ohm pot for volume control, and an audio out jack; the kit was just too loud as-was to play with it late at night when others were trying to sleep.  Then I brought the keypad wires out to a 9-pin connector to support an external keypad.  From there, I built a punched-paper tape reader, using 2 banks of 10 micro-switches wired to look like an external keyboard (wired to the NC contacts of the switches).  The force from the switches against the paper makes the circuit boards flex and some of the switches will close by themselves, so I added zinc angle bars as stiffeners and gave the reader rubber feet so the bolts won't scratch the table. 

The paper tape is 11 cm wide.  Spacing for the rows of switches is 0.5 cm.  Therefore, the holes per instruction are 0.5 cm wide and 1.5 cm long.  Because the 2 rows are staggered, there needs to be 1 cm spacing between instructions or it's possible that 2 switches on different rows could close at the same time.  One "keystroke" per line on the paper.  Since each instruction needs to be followed by an INCR, the paper tape is going to get really long really fast.  But, you can now automate pre-loading memory along with loading the program by including the [5][0][ASET] keystrokes on the paper tape.  If you make a mistake, just tape over the hole.  If you left out an instruction, just cut the paper and tape in a new sheet with the additional instructions.  At the beginning and end of the tape, leave 5 cm for a leader and trailer.  At the end of the program, you can include [reset][1][run] to have it auto-execute.

If you like, you can tape multiple programs one after another  and pause between programs.  If you put the switches all in one row, you can treat this as a player piano.  Adding a roller mechanism for pulling the paper straight through will make it easier to ensure that the paper won't slide sideways and become misaligned from the switches.

25) Twin Lens Reflex Camera
Not a lot to modify on this kit.  The kit itself is just a plastic box with 2 lenses, a roll film holder and a mirror for the viewfinder.  Gakken suggests gluing baubles and stuff to the case.  I'm not adding any mods to it.
26) Mini Electric Guitar
Gakken suggests putting the mini guitar in a different case, or adding special effects (fog cannon or strobe light).  I'm not adding any mods to it right now.
SX-150) Analog Synthesizer
Ok, if you want to mod something, here's the kit to do it with. Added the 6V DC adapter jack, and jacks for a trill generator (the DC motor kit turning fan blades in front of a photo-resistor) and a noise generator (just the audio out source from an untuned radio). The setup shown below includes the theremin plugged into the External Source jack of the top SX-150, plus the relay bank.

I got the idea for the relay bank from synth-fool .  Basically, it's just aluminum foil pads wired to one side of a relay coil, and the "drum sticks" are connected to the 6V line.  The other side of the relay coil is grounded.  Touch the "drum stick" to the pad and the associated relay closes.  I'm using DPDT relays.  One pole drives the LEDs (red when the relay is open, green when closed).  The other is connected to a 50K ohm pot that then goes to a master 100K ohm "pitch adjuster" pot, and is then wired to the connectors for the resistive strip.  The board for the foil pads is just a styrofoam sheet that I got from an art supplies shop.  I used two sheets, and sandwiched the wiring between them.  I have three toggle switches - a master power switch, and on-off switches for both the red and green LED lines.  The main difference between my keyboard and Synth Fool's is that I intended mine to drive up to 3 SX-150s, so I added an 8 switch DIP which lets me have 6 pads on one synth, four on a second and 2 on the third, or all 12 pads on one synth.  Right now, I'm just running the two synths, so I only have 2 sets of output cables and 2 100K ohm pots.  I can easily add the third set later.

The relay bank is mounted to the bottom of a tupperware container, which I also use for storing the cables.  I decided to get silly and threw in 6 mono jacks to the left side of the container to make a power strip.  Plug in a 6V adapter, and then power everything else with cables out from the power strip.  At the moment, the below setup leaves one power jack on the strip unused.

27) 8-bit micro-controller Japanino
This is the Gakken version of the Arduino, and as such is virtually unlimited in its possibilities. 

(LCD shield combined with a 2-axis accelerometer.)

(Connected to the Edo Clock.)

(My version of the Akari, with a tri-color LED in a fogged plastic tube with foil on top.) The three buttons allow for the selection of different flashing color patterns.

(Matrixed LEDs for fading in and blinking on a Christmas tree.)

(Running an 8x8 bi-color LED matrix.  LOTS of possible patterns with this one.)

28) Edo Era Lunar Clock
The standard mods are to the case, adding glitter or paint to the face.  The leaf switch does let you connect it to the Japanino to set up an external hourly alarm, but it's so noisy that it's almost impossible to debounce. 

(With the leaf switch connected to the Japanino, running a simulation of the clock with the LCD shield, and outputting an alarm to a peizo speaker.)

29) Akari Lamp
The primary mods to this one are just for giving it different kinds of paper lamp covers. There is a connector port for interfacing with the Japanino for reprogramming the LED fades, but I didn't bother with it.  No mods.

30) Theo Jansen's Animaris Ordis Parvus
I tried mounting a DC motor, but the movement of the legs was so stiff that the wires overheated.  No mods.

31) Entomopter and Ornithopter
Both of these flying machines are too lightweight and fragile to do much with. No mods.

No Number) Gakken with KIDS, Vibration plate
This is one of the special releases that's not part of the numbered series.  This particular one is a cardboard sheet placed over a speaker, with an audio circuit for controlling the frequency and volume of a simple sine wave.  Recommended mods are to just use different shaped patterns for the cardboard plate, or to use something other than the supplied white sand.  No mods.

No Number) Mini-Rhino
This is the second of the Theo Jansen mini-beests.  Suggested mods are for ways to attach a DC fan to blow the squirrel cage around, or to make a wind-up sandcrab.  I took the motor from a $1 handheld fan and connected that to the Rhino.  It works really well, but it would be better to add a variable resistor to control walking speed.

32) Denshi Mini Kit
The Denshi Mini is a scaled down version of the EX-150 electronics blocks kits. The primary mods are to make your own blocks and build synthesizer or sequencer circuits with it. I don't have any planned mods right now.

37) Theo Jansen Bipedal Robot
The third of the Jansen kits. It's designed to waddle like a penguin, so I took the micro motor from the Twister kit and taped it to the frame of the robot for power. Then, I made a penguin suit to slip over the top of the frame.

38) Flip Clock
The main suggested mods are to draw animations on the flip cards, and to use a smartphone app to do an OCR on the numbers to cause the phone to link to images on the net based on the current time. I decided to connect the Japanino to the 2 drive motors and count the pulses to determine the currently displayed time, and to then draw a 2-frame animation cycle on the LCD Shield.

39) Updated Planetarium
The original kit, #9, had an older star map and used a bigger lamp for illumination. Gakken updated the map and switched to a smaller grain of wheat bulb to produce a sharper projection. But, the suggested mods are pretty much the same as before. I didn't mod this one.

Electromagnetic Speaker
Gakken suggests turning the LED units into battle tops, or making the holder tray look like a cloth aquarium. I used two halves of a popcicle stick to make feet so the main unit stands upright, and a chopstick to suspend the LEDs from pieces of thread. The kit was originally designed to lie down flat on a table, making it harder to see the LEDs from a distance, which is why I want it upright. The LEDs spend a lot of time pointing away from the viewer, so I made a back cover using construction paper and lined it with foil for a mirror. Other mods would be to add a 6V adapter jack, and to move the power switch from the "bottom" to the "side" of the main unit if you want it standing upright.

40) Miniature Effects Camera
There aren't any suggested mods to the camera itself. It's a webcam with an adjustable lens and a mounting for tripod placement, or being hand-held. Instead, the "mods" are for different sets you can build to make your own special effects movies with insects, toys or rubber monsters. Or, you can just adjust the lens and use it as a regular webcam for Skype conversations. I cut up the pages from the mook and set them up to make a fake city and did a simple pan truck from left to right, recording in Windows Movie Maker. MM only saves to tiny 200x320 px postage stamp files, so you really need a better application to get full-screen videos.

NSX-39, Pocket Miku
The Pocket Miku is a synthesizer built on top of the Yamaha NSX-1 vocaloid chip. You can put various stickers on the case, or even place the circuit board into a new case, or automate the stylus with a servo driver. For me, the real power is in connecting the Miku to a PC or Mac through the USB port and running it from a sequencer app like Acid Studio or Garage Band. This lets you change between the Vocaloid voice and the General MIDI instruments. I wrote a Java app to let me control Attack, Decay, Sustain, Release, modulation, Low Pass Cutoff frequency, resonance, etc. The app also lets me use my Roland A-300 MIDI controller keyboard to interact even further with the NSX-1 parameters. The results are pretty cool.

41) Auto Writer
Most of the Gakken suggested mods are silly, such as making a UFO crop circle writer, and pretending to play a guitar with it (the cogs are too slow to actually play anything). You can replace the cog system with servos and drive them with an Arduino to make your own 2-D plotter. I haven't modded this kit.

42) Electronic Steel Drum
Gakken doesn't have any suggested mods. You could try hanging the pan from a different frame, or put it in some kind of housing (anything that touches the pan will deaden the sound). The alternative is to use the second pick-up coil to listen to sounds produced by various house-hold items, like doors, windows, vacuum cleaners and metal pails. I'm running the signal out from the amp to the LFO-in jacks of my other synthesizers.

43) Hurricane Humidifier
As of the time the Steel Drum came out, Gakken had taken down the "Next Kit Up" link from the Otona Kagaku pages. The only mention of the Humifier is on the back page of the Drum mook, and there's no tentative release date or pricing. So, they could change their mind and come out with something different, or not release anything for the next 9 months.