Davo
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Posts posted by Davo
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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.
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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.
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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.
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That'll work fine. Thanks!
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I'd like 36 knobs, please.
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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.
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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.
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It looks like your corrections did the trick. I've yet to fire this one up yet, however. Still waiting for Jameco.
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You might also want to check out the arcade game part suppliers for rotary controllers.
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Please post what you have of the resistor list.
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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.
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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.
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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.
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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!
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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?
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BTW, that was "Borne Identity". "Johnny Mnemonic" was about data smuggling and the Yakuza.
Davo
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According to ucapps.de and SmashTV's site, some 2.7 nanofarad (2700 picofarad) capacitors are called for. However, it looks like SmashTV is linking to a Mouser page for 2.7 picofarad caps. Which is the correct value?
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For those who didn't know already, you can use toner transfer paper (the wet kind) to make decals.
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So this is back to the earlier discussion of resistor ladders controlled by a DOUT module?
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Sorry if this has been asked before, but what's so special about the max525 chip? I perused Jameco and found the following DACs that I think might be suitable to build a lower-cost AOUT. Would someone who knows better please check this out?
DAC1222LCN (#14980) 12-bit $9.95
7109CPL (#43764) 12-bit $7.49
TLC5615CP (#239425) 10-bit $3.49
IMHO, this lower-cost AOUT module ought to be able to support more than just two 16-bit outputs at once. Or at least have an extended version of the 2-output one.
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FWIW, 62256 SRAMs are fairly easy to find on Ebay. A few months ago I bought around 60 of them for an unrelated homebrew project. They're almost always pulls, but they work well and the price is good.
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A big problem with that thing on Ebay is that DD 3.5" disks are rather difficult to find now and the device most likely uses a weird format that isn't readable anywhere besides that device. The MBSEQ has code that looks like it could be tweaked to do what I'm talking about. Data could be dumped to and from a bankstick.
Davo
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It occured to me that the midibox core should be able to handle capturing keyboard setup dumps (ie, from a Roland AX-7). I guess the MBSEQ provides something like this, but I'm not sure.
Davo
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It might still be salvagable for a more experienced solderer. For me, I'd solder some bare buswire to the broken stubs (even if they're flush, this should work). Plug the chip into a high-quality machined-contact socket, then solder the buswire pins to their respective holes. Add a little epoxy to make sure it never comes out and you're good as new (sort of).
AOUT jacks
in MIDIbox FM
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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?