Davo

Something I was mulling over today was a reinterpretation of the keytar and this thread seems to be the right place to do a brain dump. The MBHP seems like just the brain to run it. Suppose we start with a wooden base (I like poplar). Mount four or five octaves on it. The neck would be a hollow aluminum bar bolted just behind the keys and is done so in such a way that it can be easily flipped around to make it left-handed. The neck contains a ribbon controller, expression bar, buttons, dials, and so on much like the Roland AX-7. Screwed over the neck and behind the keys is the control console. Here are a numeric keypad, LCD display, and patch buttons, and perhaps some assignable sliders.

This calls to mind a similar question. Jameco #230535CC is a 25-watt triple output supply for about $24: more or less perfect for a Midibox synth. Since it's regulated, I removed the voltage regulator. I then noticed the voltage drop and decided to omit the rectifier. After all, it's not like I'll be constantly messing with the inside once I get it up and running. Then I noticed that big capacitor. Do I really need that 2200uF there now that filtering is taken care of by the regulated power supply? It's not a big problem now, but when I get to work on my SID machine, considerable useful space will be saved by omitting these eight caps.

This sounds nice, but how would one interface it to a Midibox SID or FM? I'm thinking of building one for my Paia Fatman.

Hmm.. Yesterday I came across this site: http://www.colinfraser.com/m2d/m2d.htm, which details a much simpler way to convert midi to sync-24. All told, it uses a PIC 12F629, an optocoupler, six resistors, one capacitor, and two midi-style jacks.

I've been looking at the Prophet64 setup and I'm wondering where I can get a sync-24 converter. This seems like something a Midibox core module could handle. Anyone here know where to go from this point?

Suppose I have Midiboxes SID and FM, and a Paia Fatman or two in a rack. Together they have a lot more outputs than typical keyboard amps have inputs. The obvious solution would be a simple 12-channel (or so) mixer in a 1U package. The controls would be level, panpot, mute, and a master output level with maybe a headphone output. The output would then go to a guitar amp or two, easily and cheaply available from a pawn shop. I've yet to see an amp intended for keyboards in the local pawn shops. The summing amp circuits discussed when I brought up adding an internal mixer to a synth sounds like a good place to start. Opinions?

Sounds like impatience. Plaster should be cured for at least a day and kept slightly damp after it sets. Mist it lightly, then put plastic over it. It should be very difficult to scratch cured plaster with a fingernail. Here's another idea borrowed from makeup. Foamed latex prosthetics are very realistic, but can be used only once, are costly, and it's a difficult and long process. A much cheaper and easier way is called shell latex. It works well for stage, but looks funny for extreme closeups as in film or TV. For this technique, you omit the inner piece and instead paint liquid latex around the inside of the mold. For fiberglass, do the same thing. Make your model from something that plaster won't stick to. Make a mold as described before. Now paint the inside with resin, let it set, then add resin mixed with fiberglass. You should be able to easily get walls of uniform thickness with no need for alignment.

Very nice! I've had some experience with theatrical makeup, and this looks very similar to how foamed latex prosthesis are made. One thing puzzles me: what was the purpose of spraying the female mold with laquer? Here's an approach that's closer to the foamed latex procedure: This should allow for better control over the thickness of the box's walls. Make a negative of what will be the inside of the box. Avoid undercuts for obvious reasons. Cover this with wax and build it up to form what you want the outside of the box to be. Ladle a thin plaster over the negative, making sure there are no bubbles against it. Build up a layer of, say, 1cm. Then stick it into a box filled with plaster, as you did. Before you do this, bore at least three holes equidistant around the edge of the negative. Insert metal rods into these holes. When you put the inside negative into the plaster, the rods will stick into the wet plaster. These rods will remain in the plaster and slip out of the inside negative. When the plaster is cured, remove the inner negative and as much wax as you can. Put the plaster mold and inner negative into an oven on low to melt out the remaining wax. You will now have a pair of perfectly-fitted male and female molds. The metal rods will make sure the molds stay properly aligned.

Am I too late to bump my order up from 36 to 50 SIFAM knobs?

I was wondering what would be most appropriate for AOUT jacks. TK's FM box has the AOUT signals going out through a DIN of some sort. I think 1/4" jacks might be better for interfacing with seperate modules. Opinions? If I use 1/4" jacks, what should they be labeled? Pitch 1 through 4 and Gate 1 through 4?

So, you just want discrete triggering? Now for soldering and glues: I've never soldered piezo discs before, but I understand it's similar to soldering unwires solar cells. In that case, it's best to use paste flux. Brush some on the device where you want the wire. Put the wire in place and heat with your iron. Make sure the iron has a somewhat heavy load of solder so it wets both the wire and the piezo. Apply more solder if necessary. Epoxy sounds like an ideal choice for gluing the piezos.

Consider building an analogue to an electric guitar. Recall how pickup coils work. Now, here's my drum idea: Start with a ring of tough plastic or graphite. Put a layer or two of leather on top. Now wind a flat coil the same diameter as the drum and put it on the leather. Glue a thin piece of steel to the center of the leather. Add one or two more layers of leather. Top with another ring of tough nonmetallic material. Clamp this sandwich together real tight with nylon bolts and nuts. Striking this drum will cause the steel slug to vibrate within the coil. The induced currents are then run through amplifiers, filters, and other synthy gizmos. Unlike typical on-off electronic drums, this thing will probably make a noise no matter where you hit it. I cooked this up over a long drive today. I haven't built any of this, but I just thought I'd throw it out for someone else to play with. [1] I'm thinking vegetable-tanned leather (the stiff sort that pictures can be carved into). Rawhide might be better. I don't know for sure.

Among arcade game collectors, leaf switches are considered superior to microswitches. A big reason is that they don't add any feedback to the buttons. Find an arcade machine from the 80s. Notice how smooth the buttons feel? Now compare this with a more modern machine. The button has a click to it. If anything else, your leaf switches can be very cheap to replace by making them yourself. They're probably little more than some spring steel coated with something like brass, copper, or nickel riveted to some bakelite. I don't know about plating spring steel, but perfboard and pop rivets should do the trick for putting new switches together.

That'll work fine. Thanks!

I'd like 36 knobs, please.

I've seen round plexiglas rods before. I'm not sure where to get them now, but they seem to be commonly used on venetian blinds. Perhaps you can cannibalize some old curtains and blinds to get rods.

I used a standard tip and used desoldering braid. There's no need to get a solder-sucker if you don't already have one. I have one myself, but I found braid to be easier. Lay the braid over the connections and press the iron to soak up the solder. When that was done, the pins can be lifted very easily with the tip of an exacto knife. Soldering them onto the OPL3 module was another story, but I'm very impressed with the job I did. I started by pressing the chip to the board with a thumb, then lightly pressing the corner pins. There is enough solder left on the pins to hold the chip on. Now to make the permanent connections, carefully approach the pin from the side. This will melt a bit of solder left on the pin and the tin spread on the board, assuming you bought a professionally made board. Now briefly touch the pin where it meets the chip body. Solder will flow down the pin and into the gap between the pin and its pad. Inspect with a magnifying glass. If you have access to a dissecting microscope, use that.

It looks like your corrections did the trick. I've yet to fire this one up yet, however. Still waiting for Jameco.

You might also want to check out the arcade game part suppliers for rotary controllers.

Please post what you have of the resistor list.

I just got some more boards from Smash today. Among them is the OPL3 module. I noticed something odd that nobody else has mentioned: the silkscreen does not agree with the schematics or Smash's part list ???. In particular, find C3 and C4 in the schematic (top middle). Now find them on the board (just right of the LED in the lower left corner). Notice that C3 in the schematic is an electrolytic and C4 is nonpolarized. Now look at the board and see that the roles are reversed. C5 and C6 are also swapped. Some more discrepencies :o: C19, C20, C21 and C22 are shown on the OPL3 module page as being electrolytic, probably 10uF. The schematics, however, show C19 and C21 as being .1uF ceramics. Now looking at the schematic, those capacitors seem to be C31, C32, C33, and C34. In the schematic, C23 is ceramic and sits next to C24, an electrolytic. On the silkscreen, C23 is an electrolytic and is nowhere near C24, which is still electrolytic. In the schematic, R1 is the 220 ohm resistor tied to the LED. On the silkscreen, this resistor is R23. There are assorted other weird number switches. I thought this might have been a bad batch, but I see that this: http://avi.dezines.com/mbhp/images/OPL3R1qv.gif is also incorrect. Would someone please tell me what the correct silkscreen is? I've already soldered the surface-mount parts on and I'd rather not do that again.

Cats typically don't like citrus or garlic smells. That's what many cat-repellents smell like. You might want to try a toned-down electric fence.

I've noticed a new behavior from my cat. Whenever I pull out my synth stuff and start playing around, my cat runs in from wherever she is and plops herself into my lap. She doesn't seem interested in playing with the keyboard or synth.

The object is not elegance, but simply a mono output. Sometime later I'd like to make a simple 1U mixer specifically for synth use. That link looks like a very good place to start. Thanks!

I'm thinking of putting a simple mixer in what will become my SID and FM synths so I can simply plug in an amp and go. This circuit: http://www.musicfromouterspace.com/analogsynth/monomixerpage.html seems appropriate. Comments?