Review: Kit #34, the Delta Twister


(Cover taken from the Otona no Kagaku site.)

Kit #34, the Delta Twister, is now out.  2940 yen.

Otona no Kagaku is pretty pleased with this one, advertising it as a unique design for a wind-up plane never seen before. Designed by Yusuke Takahashi, this entomopter gets it’s name from the triangular front wing, and the “twisting” way the wing flaps.  It is a much more impressive craft than the entomopter or ornithoper were from kit #31.  I haven’t had a chance to take it outside yet (it’s raining), but Gakken claims a flying time of 10 to 30 seconds, with a distance up to 30 meters.  With the rubber band only partially wound, it’s safe to fly indoors as long as you don’t aim at people’s faces.  The key point is that it’s very light at only a few grams without the DC motor.  Made from carbon fiber rods and mylar sheeting, the Twister is powered either by the wound rubber band, or a coreless motor connected to a charged capacitor.  The drive rod at the front connects the crank handle to the front wing, and causes the wing to flap at a relatively slow rate of 1-2 complete beats per second (with the band partly wound; 5-10 bps with the motor).  Normally, this would be too slow, but the greater surface area of the front wing pumps a lot of air, and the back wing acts as a stabilizer/parachute to help keep the Twister aloft.  The launching instructions state that you should toss the Twister as you let it go, but simply dropping it works fine, too.

The operating principle is very simple.  You wind up the rubber band with the hand crank at the front and when you let go, the twisting crank makes the drive arm move up and down.  Since the arm is connected to the front wing about half an inch off-center, the wing then wiggles, with one side going up, then the other. The mylar sheet is big and loose enough to generate a wind strong enough to feel against your hand, for forward propulsion, and the tail wing acts as a stabilizer, as well grabbing enough air to slow any downward motion ala a parachute.


(Rubber band version. Note the handcrank at the front.)

Initially, I decided to build the rubber band version because it looked like that would make the construction of the wings easier.  This version only has 17 parts, not including the double-sided tape.  There’s a 60 minute suggested assembly time, but I focused so hard on understanding the instructions and trying to get it right the first time, that I was stunned to discover that 2 hours had passed.  The basic idea is very straight forward.  You have a small white silicon tube, 6 carbon rods (1mm by 170mm, three 0.8mm by 220mm, and two 0.8mm by 170mm), a couple mounting pieces, 2 large sheets of mylar, and a folded paper guide. Cut six 3mm pieces from the silicon tube (it may help to mark out a 3mm line on a piece of cardboard and use it like a cutting board) and put five of them on the carbon rods as shown in the diagram. The 1mm rod is used for the central rod for the front wing.  The rest are structural supports for the two wings.  Put the 1mm rod and two of the 220mm rods into the three hole holder as shown, and slide the flexible skeletal bar on to the other end as shown.  Don’t worry about positioning the bar yet.  This gives you the skeleton of the front wing. For the back wing, connect the two 170mm 0.8mm rods to the straw holder and put the wing tip bars on the opposite ends.  Put the remaining rod into the middle hole of the straw holder and slide the end straw holder onto the rod from the opposite end.  This completes the back wing skeleton.

You’ll notice that the plastic pieces that attach to the mylar have a flat side and a ridged side.  As you put them on the carbon rods, make sure the ridged side is face up.  When you’re done with the skeleton frames, cut the double-sided tape as shown in the diagram on page 3. Lay the folded guide sheet out flat on the table and tape one of the mylar sheets onto the guide with Scotch tape.  The instructions state to start with the big wing first, but it doesn’t really matter. You can get both wings from one mylar sheet; the other is just a spare in case you need it.  Pre-position the two wing skeletons so they lie evenly within the gray areas of the guide sheet (this is where you adjust the skeleton bar on the front wing to the correct position).  Put the double-sided tape on the mylar, with the backing still on the other side, as shown on the guide sheet.  When you’re ready, take the backing off one piece at a time and put the skeleton on each piece of tape, centering the carbon rods within the gray boxes of the guide sheet.  Make sure now that the flat sides of the plastic pieces are face down on the tape.  When the rods are affixed to each piece, cut the mylar along the guide lines with an x-acto knife and wrap the excess mylar around the rods.  Remove the extra paper from the guide sheet, reposition the mylar for the other wing, tape the edges of the mylar to the guide sheet and repeat for the other wing.

Make the rubber elastic into a loop and knot the ends.  Put the loop over the crank hook of the front wing and use the puller tool to pull the band through the body straw.  Put the straw in place on the front straw holder, slide the back wing holder over the straw, wrap the band around the back wing end cap and put the end cap in place.  Remove the puller tool.  You’ll probably want to wrap a piece of Scotch tape around the end cap to keep it from spinning when the rubber band is wound up.  Connect the free end of the front wing central carbon rod to the back wing tip piece and you’re done.  Wind up the Twister using the front crank and let go.


(DC motor (silver cylinder above the white gear) and cap (blue cylinder at the back.)

To use the DC motor, pull off the back end cap, remove the band and front crank piece.  Replace the front crank piece with the gear holder.  Attach the gears and DC motor.  Route the wires, and mount the capacitor board at the back.  Check positioning to allow for easily plugging into the battery holder.  Assemble the launcher/battery holder.  Put in 2 AAA batteries.  Plug the Twister into the launcher using the 2 pins on the capacitor board.  Press the battery switch and let the wing flap for 10 seconds to charge the cap.  Pull the trigger to launch.


(Launcher/Charger.)

The only tool needed is the x-acto knife.  All pieces are snap-fit plastic, and they will need to be removed from the form frames and any excess plastic removed.  However, if you’re using the battery holder, you’ll need a small Phillips driver for the 2 screws used to keep the case closed.


(Front of launcher.  The 2 pins on the capacitor board plug into the jack of the launcher.  When you pull down on the battery switch at the back, the wing immediately starts flapping and the cap. begins charging.  Wait 10 seconds, then squeeze the pusher trigger.  This simply pushes the circuit board forward and frees the 2 pins from the jack.)

I did find the process of switching from the rubber band to the motor to be very difficult (maybe another 17 pieces, and took 1 hour to complete).  The rubber band crankshaft piece and the gear holder shaft both pressure fit onto the 1mm carbon rod, and I needed to do a lot of pushing and pulling that could have damaged the mylar.  This is not something I want to do often.  I also had trouble with the gears.  Initially, the gears were very stiff, and the way the middle gear fits into the teeth part of the motor kept causing the motor to pop out of the shaft when I put them together.  The cap wouldn’t hold a charge, and the motor got really hot when I tried to run it.  The problem was that the motor pressure fits into the hole in the gear shaft, and it wasn’t completely pushed into place.  After really mashing in the motor, the gear assembly turned much more easily.  If you find that the gears require work to turn with your fingers, try pushing the motor in a little farther (but be careful to not snap the gear shaft).  The next problem is that the capacitor mounting piece on the straw body slides too easy and the Twister will rotate onto its side as you’re charging it with the launcher.  If this happens, just hold the Twister in place with your free hand.


(DC motor version of the Twister with the cap. circuit board pins plugged into the launcher.)

While this kit, and the next one, aren’t numbered on the packaging, the website URLs indicate that this one is #34, and the next will be #35.  So, technically, the Delta Twister isn’t actually a “special kit”.  The mook reflects this.  The first 4 pages are examples of flapping-wing aircraft from the Studio Ghibli movies, mainly from Laputa, Castle in the Sky.  The next 14 pages are various descriptions of the principles of flight, starting with air flow, then including dragonflies, bees, planes and helicopters.  There’s a 10-page interview with the designer and photos of the Twister in a wind tunnel.  Another 4 pages on descriptions of the technology behind the coreless DC motor and capacitor, and an 8-page photo essay on the proper way to launch the Twister (two pages demonstrate an extender pole for launching the DC motor version from an additional 6 foot height).  We get into the suggested mods in the next 8 pages, including changing the wing material to make a big gold fish, hanging two twisters upside-down from a small dirigible, and adding a second motor to drive an RC-controlled tail fin.  2 pages showing a hand-built 1-seater wooden glider, and 4 pages showing an amateur project using a Primer-V2 robot that can ride a scaled-down bicycle without training wheels or falling over.  An 8-page interview and photo essay on Fujitsu’s new super computer (currently the world’s fastest), and 7 pages on the principles of geodynamics and fossil formation.  The mook wraps up with the assembly instructions for the Twister, and a 16-page manga by Yoshitoo Asari that originally ran in Gakken’s school kid science books back in the 70’s. Asari started out at Gakken drawing the Manga Science sections before going off to create his own Space Family Carlvinson and Lucu Lucu gag manga.  This particular installment teaches the principles of aerodynamics.

Overall, the mook is again a great collection of photos, but there’s not much in the way of historical objects this time.  Lots of interviews and theory in Japanese. I personally really like the Asari manga at the end, and will eventually get around to translating it.  The Delta Twister itself is very eye catching, and the Japanese people I’ve shown it to find it very cute and fun to play with.  The mylar can be damaged by strong winds and won’t fly well if damp, so there’s a limit to how often you can fly it.  You’ll want either an open field like a baseball diamond, or an indoor basketball court (I think it would be good for frisbee golf).  It is a fun kit, and if you’re a science teacher you may want to get two (they’re still relatively cheap even after the import mark-up) to have one each rubber band-, and DC motor-powered (since it’s difficult having to switch between them).

Next up: Kit #35, two-cylinder steam engine

SX-150 Mark II Patch Template


One of the things I think is missing from the SX-150 Mark II page is a blank template for recording sound patches.  So I mocked one up from the examples they’ve got on one of the other pages using Gimp. Not all that great looking, but it’s better than nothing.  I decided to add the Tuning control (located on the back of the unit) because that has a big impact on the kinds of sounds you can get.

Anticipating the Delta Twister


(Image from the Otona no Kagku site, used for review purposes only.)

The Delta Twister kit hit the shelves in Tokyo on the 17th, but it won’t reach me in Kyushu until closer to May 20.  In the meantime I can make a few comments on it while I’m waiting.  If you watch the youtube videos, you can see that this kit has a much longer hang time than either the ornithopter or entomopter had.  Depending on how much the rubber band is wound up, and whether there’s any wind, the Delta can stay airborne for up to 30 seconds.  And, while the spec given in the newsletter says that it can travel 10 to 30 meters, the videos show that the Delta tends to go around in circles.  So, actual distance from you after you throw it depends on whether you can trim it to hold a straight line.

The assembly instructions aren’t that different from the entomopter. There look to be about 40 parts, with a suggested assembly time of 60 minutes.  The main difference will be in assembling the back wing and the handheld launcher.  Then, there’s also the option of putting in the DC motor.  This is not a simple matter.  You’re not going to be able to quickly switch out the rubber band for the motor and then go back right away.  Page 1 of the PDF is the parts list. Page 2 shows the assembly of the body, and 3 is the assembly of the wings and mounting the rubber band.  Page 4 starts out with removing the rubber band and routing the wiring for the motor and the capacitor.  I was wondering how the cap. would be recharged, and the answer is given in the second half of page 4 – the handheld launcher holds 2 AA batteries, which connect to two small contacts at the bottom of the capacitor.

If you’re going to use the Twister for a science class, and if you have a large enough budget to accommodate the import markup, you may want to buy two kits and dedicate one each to being hand-wound and motor-driven.  Either way, I think the Twister will be more fun to play with than kit 31 was.

The last comment I have is with the manga at the end of the mook.  This time, it’s going to be a “Manga Science” reprint by Yoshitou Asari.  You may remember Yoshitou as the interviewer in the “Homo Volant” article from Mook #31.  He’s a manga artist that got his start doing the “Manga Science” series in the 70’s, before going on to draw “Space Family Carlvinson” and “Lucu Lucu”.  He also designed the Angels in Neon Genesis Evangelion.  So, yeah, I’m looking forward to this issue.

 

Unknown skyship


I’ll post the contents of the Gakken email newsletter tomorrow.  In the meantime, Kit 34, the Delta Twister, is now on the shelves in Tokyo (but won’t make it to me in Kyushu for another 2-3 days).  The Facebook page just uploaded the below video of the “unknown spaceship” – two Twisters connected to a balloon, and LEDs on the tips of the lead Twister.  It looks funny,  but would fly better if the balloon were heated.

They also uploaded the official ad video for the kit.

 

SX-150 Mark II Usage


 (Image taken from the Otono no Kagaku site.)

There are certain Otona no Kagaku kits that have a learning curve, or have a certain number of things you can do with them that involve longer explanations. The main examples being the Japanino, the Denshi mini Blocks, and the EX-150 expansion pack.  We can add the SX-150 Mark II to this list.  The primary reason is that it doesn’t come with an instruction book and the supporting information is spread out across several youtube videos.

If you’re familiar with sound synthesis, then the first concern is with exactly how the controls affect the waveforms, followed by which patches produce which sounds.  On this count, Gakken hasn’t provided much information – 4 patch settings, to be exact. But, by watching the videos you can see what the controls do pretty quickly.

On the other hand, if you don’t know the difference between a “patch” and a “squarewave”, then the Mark II is going to be difficult to figure out.

Waveform Types

(From wikipedia)

Essentially, analog synthesizers start out with a simple sine wave. This gives you a pure note of one frequency.  When you press a keyboard key, the note starts playing at full volume (called “instant on”) and stops playing when you release the key (“instant off”).  It’s a nice concept, but gets boring fast.  What you want to do next is change the frequency, or “pitch” of the note.  With a keyboard, you do this by pressing a different key (where each key is assigned to a different note). With the Mark II, you’re using a solid ceramic strip and a contact wire (the stylus) – to change the note, just touch the stylus somewhere else along the strip.  Or, turn the Mark II over and adjust the Tuning control.  The Tuning control changes the range of notes (the frequency range) of the ceramic strip.

I should mention here that the Mark II doesn’t actually use a sine wave for the starting waveform.  I don’t have an oscilloscope to verify this with, but it’s probably a square wave. If you crank Tuning way down, you get a “boop-boop-boop” sound instead of a continuous low-frequency hum.  If you want a nice, clean bass guitar sound, the closest you’ll get is something like a fart.  But at very low frequencies, along with the VCO Rate and Depth controls, you can get some really cool “house” effects.

Envelope

The problem with instant on and off sounds is that they’re not all that common in the real world.  You do see them with percussive instruments like the snare drum. But something like a bell is instant on with a diminishing after-note, and a violin can have a slowly rising volume that slowly diminishes.  That is, things like a violin or a flute aren’t instant on or instant off.  This is where the “envelope” comes in.  Early versions of the envelope consisted of Attack, Decay, Sustain and Release settings, also called the ADSR.  Attack is the time it takes for the sine wave to reach full volume from when you press the key.  If Attack is set to 0, it’s instant on.  So, if you want a soft sound like with a flute, you might set Attack to 0.25 seconds or 0.5s.  Decay is the time that the sine wave takes to drop from full volume right after Attack finishes.  Sustain is the level that Decay stops at.  And Release is the time to go from the Sustain level to zero volume when you let go of the key.  So, if Decay is 0, Sustain at 100% and Release is 0, you have instant off.  To get a bell sound envelope, you might set Attack to 0, Decay to 0.1, Sustain to 70% and Release to 3s. (Depending on the synthesizer, and other settings, of course.)

The Mark II has a simplified envelope control that is just AD – Attack and DecayAttack goes from about 0.1s to 1s, and Decay from 0.1s to 5s (roughly).  Regarding Decay, there’s a fixed sustain value and the volume won’t go to 0 until you take the stylus off the ceramic strip.

Additionally, there’s the Power switch.  The Power switch has 3 positions: On, Off and Gate.  The Gate position more or less disables the Attack and Decay controls (not completely, because they do still have some effect with Gate On).
LFO and VCF

The next section is a bit more complicated.  We need to develop a way of getting a warbling or trill effect, as well as adding additional sine waves to our note to get the range needed to imitate a guitar or cello.  This is where the VCF and LFO controls come in.

The LFO, or Low-Frequency Oscillator, adds a signal between 1 cycle per second (cps) to maybe 2000 cps.  In the case of the Mark II, the LFO is how we get our trill effect. What it does is change the frequency of the note we’re playing by a certain percent plus and minus.  The total effect is controlled by the LFO Wave, LFO Rate and LFO Depth settings.  The LFO Wave switch selects either a Triangle or Square wave shape for going from our minus to our plus values (either instant switch up and down, or straight line).  The value of minus and plus is set by the LFO Depth control (roughly 0.01 to 0.5 – I’m guessing here). So, if we have LFO Depth turned a quarter of the way, this may be a multiplier of 0.2.  If the note we’re playing is 2000 hertz (Hz), then the trill might be jumping between 1600Hz and 2400Hz.  And, the rate of the jumping (the rate of the trill) is set by LFO Rate (roughly once/second to 2000 times/s.)  In combination, you can get a low throbbing beat, or fingernails across a chalkboard.

The VCF, (Voltage Controlled Filter or Voltage Controlled Cut-off) is used with the LFO to limit the frequency of the sound that the LFO makes.  If you look at the Triangle and Square wave shapes, you can see that they make sharp, abrupt changes.  This represents high frequency noise being added to our sound out.  Sometimes we want this noise and sometimes we don’t.  The Mark II has a pressure-sensitive button for controlling VCF.  The harder you press the button, the more high frequency noise gets passed by the filter into our output sound (essentially it’s bypassing the Cutoff control).  The VCF button is instant on, instant off, and adds high frequency components as long as you hold the button down, regardless of what the rest of the sound envelope is doing.

The Mark II adds one more pressure-sensitive button, the LFO.  The LFO button acts as a pitch bender for the ceramic strip, from roughly (0.1 to 0.2 of the note being played). The full amount of the pitch bend depends on the Pitch Env. setting.

When we take the entire waveform produced by the ceramic strip setting, the LFO and the VCF circuits, we have lots of sounds consisting of low-, mid- and high-frequency parts.  We use the Pitch Envelope control to boost the sound amplitude over time, as a triangle envelope.  Depending on the other control settings, Pitch Env. can have no effect at all, or it may soften the output sound a small but noticeable amount. The main impact Pitch Env. has is on the range of bending you get when pushing the VCF button, and the height of the AD envelop for the Attack and Decay controls.
Cutoff

The Cutoff control acts as another filter, limiting the top frequency of the sound out from the Pitch Envelope circuit. That is, it’s a low frequency pass filter. And, it gets bypassed depending on how hard you press the LFO button.
Resonance

We can argue that Resonance adds a “ringing” sound at the Cutoff frequency. Essentially, it boosts the amplitude of frequencies in the waveform from the Pitch circuit that are closest to the Cutoff frequency. This effectively adds high frequency sine waves to the  sound you’re creating, giving you more of a bell or “chirp” effect.

I’ll repeat it here – the Tuning control on the back of the box HAS A MAJOR IMPACT on the kinds of sounds you can get.  If you don’t mind modding the Mark II, rip out the speaker and put the Tuning control in its place. If you already have this kit in your hands, you’ll immediately understand why I say this.

Now, if you look at the Otona no Kagaku videos, you should have a better understanding of what each of the controls are doing.  If you freeze frame any given video, you may be able to see the control knob settings (the “patch settings”).  However, the first couple videos are accompanied by a patch chart.

If you want, you can add a keyboard pattern to the ceramic strip.

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Gakken Instructional Videos

Synth Brass

(Brass patch)

Bell Cricket

(Bell Cricket patch)

Synth Bass Techno


Dog and Cat Voices

Otona no Kagaku newsletter #150


Otona no Kagaku newsletter #150 arrived in my mailbox last Friday. The main news, of course, is on the upcoming release of the latest kit, the Delta Twister. The subjects covered this time are: The Twister, the development of a new 2-cylinder steam engine, and an upcoming car show exhibit.

1) The futuristic “Delta Twister“, with its triangular wings (delta) and flapping action (twist) is about to come out. Weighing between 6 and 9 grams, it will have two forms of motive power – the rubber band, and an electric motor. 2,940 yen ($35 USD), and a May 17 release date.

Specs:
Length: 39 cm
Width: 40 cm
Height: 4.5 cm
Weight: With rubber band: 6g; with Motor: 9g
Wing Shape: Delta Wing
Wing Area: 7.3dm2
Center of Gravity Position: 15 cm from the nose
Body Materials: Carbon Fiber
Wing Material: 8 micron low-profile film
Wing Flap Rate: 1.5 to 6 Times/Second
Flight Speed: Rubber Band: 1.5m/s; Motor: 2m/s
Range: 10-30 meters

Youtube Videos: Outdoor and Indoor.

2) Hot on the heels of the Delta Twister, the editorial department is in the middle of developing yet another engine. You may remember the steam car from Kit #7. This time, kit #35 is going to be a 2-cylinder version. An alcohol lamp will heat the boiler, producing the steam to drive the engine. With 2 cylinders, this kit will be much faster/more powerful than #7 was. An external drive rod will turn a pulley for powering other items. No price set yet, though the tentative release will be at the end of July.

3) Le Volant Car Show
Gakken publishes the “Le Volant” car specialty magazine, which is hosting a road show on May 13 in Yokohama. On top of this, Otona no Kagaku is going to have live demonstrations of the Udar synthesizer every other half hour (10:30, 12:30, etc.), alternating with a demonstration of something they’re calling the “ocarina” (no idea if this is a plain flute-type ocarina, or a new electronic toy).

Location: Yokohama Red Brick Warehouse
Udar Event Fee: Free
Check the above link for details

SX-150 Mark II


I’ve been holding off from getting the SX-150 Mark II because of the 7,350 yen ($90 USD) price tag.  However, I did get a bit of a windfall from some piecework recently, and given how hard it was getting to the bookstore on crutches from the school I work at, I figured that I’d kill two birds with one stone – buying the Jansen DVD and the Mark II at the same time.

(The original SX-150.)

The Mark II is an enhancement of the SX-150, also known as the Synthesizer Chronicles special kit. The original “Chronicle” was a kit that you had to assemble, and included the mook.  Variable controls were for LFO Rate, Attack, Decay, Pitch Envelope and Cutoff.  The three switches were for Resonance ON/OFF, LFO Wave (square or triangle) and Power (Off, Low Volume and High Volume).  The External Source jack allowed you to drive the kit from a voltage source instead of the resistive strip. The build-in speaker was very tinny and thin, so using the Output jack to drive mono headphones or run audio to a mixer was a much better choice.  The good part of the kit was that it was cheap – 3,360 yen, and that made it easy to justify modding it.

(Mark II. It’s about 6″x4″x1″)

The Mark II builds on the original, replacing the Resonance switch with a variable control, and adding an LFO Depth control.  The power switch has been changed to Off, On and Gate; where Gate disables the Attack and Decay controls.  The External Source jack has been relabeled as “Line In”, but probably works the same way.  Finally there are two new pressure-sensitive push button switches: VCF Modulation and LFO Modulation.  The tiny built-in speaker is still mostly pointless – you’re better off plugging headphones into the Output jack instead.  The Output audio is pretty rich and clear in comparison.  Now, this is not a kit; basically you just get a small box that contains the Mark II, a sheet of silvery labels for customizing the knobs, and a foldout sheet with warnings (don’t play the Mark II in the shower, and don’t leave it in your car with the windows rolled up in the summer) and brief descriptions of what each of the controls do. It’s the same descriptions found in the highlights page on the website.

The one thing I really do miss from the Synthesizer Chronicles mook is the suggested list of control presets (patches) for making different kinds of instrument sounds.  You’re kind of left on your own this time.  Although, the Otona no Kagaku site does have a selection of youtube videos demonstrating the use of each of the controls.  One of the first things they did was to draw a piano keyboard layout on a piece of paper and tape it next to the resistive strip, which makes it easier to figure out where to put the stylus to play any given tune.


(Tuning control is at the top right.)

Right out of the box, the Mark II was really high-pitched, with a limited frequency range.  Initially, I thought it was because of the control knob settings and I was resigned to spending time trying to figure out how to get bass sounds.  But, I decided to look over the instruction sheet first, and immediately noticed that there’s one additional control on the bottom of the case, marked “Tuning”.  This is the control that adjusts the frequency range for the resistive strip, and is so incredibly powerful that I’m stunned that they didn’t put it on the top of the case with the other knobs.  If you intend to use the Mark II in live performances, and there’s no reason not to mod it to do so, then you’ll REALLY want to get to Tuning without having to turn the box upside down.  Gakken should have left out the speaker and put the Tuning control in its place.

Given the price of the synth, the construction of the two modulation switches is rather cheesy.  There’s no real force feedback, you have to listen closely depending on the waveform. being produced, to tell if the LFO Modulation button is even doing anything. The amount of pitch bending you get is dependent on a very small range of pressure on the switch.  The VCF Modulation is much louder and easier to sense, but still has a narrow pressure range.

Because Tuning has such a big impact on the final sound of the synth, in combination with the other controls there’s a relatively steep learning curve.  I expect to be kept entertained with it for a few weeks just trying to see what sounds I can get from it.  After that, I’ll want to replace the resistive strip with something a bit easier to control consistently, make the Tuning control more accessible, and see what Line In does.  If you’re in Japan, get this kit, it’s a good introduction to monophonic analog synthesizers.  Otherwise, the import markup makes it less attractive, unless you’re a professional musician and want something unusual to add to your tool set.

Note: If you want to hear the kit, check out the Otona no Kagaku youtube videos.