Duggle

To get a handle on what might be possible with this chip its best to consult the datasheet: '>http://www.funet.fi/pub/msx/mirrors/msx2.com/vortexion/YMF262.PDF Naturally modulation can be done in software, but only within the limits of the resolution of the parameter, and also at a rate that the PIC can update all parameters. This is more in the mS rather than uS so that software envelopes and LFO's are possible but useful audio frequency modulation in software most likely not. cheers

hi, LED's in the multiplexed displays such as the MIDIbox LC LED rings and level meters do get reverse bias (this means they see a reverse voltage as the display matrix is scanned). However it would be about 4V max, because there will be a voltage drop on the outputs of the Dout drivers. The rated voltage on the LED is likely to be a conservative figure therefor its highly unlikely to be a problem. cheers

Of course. But this is just free form experimentation, something that can be setup (and deconstructed) in 5 minutes. Some peoples PC's take more than 5 mins just to boot up ;)

if you would like to use a physically smaller cap to privide ths same "smoothing " effect, do this: With the positive side of the cap still connected to Ain, wire a resistor between the wiper of the pot and Ain. This will lengthen the time constant. Time constant can easily be calculated as R*C (in ohms and farads). Basically if you scale the resitor up by a factor of 1000 then you can scale the cap *down* by a factor of 1000 and have the same response! With a 10uF cap try say 22kohm resistor.

Just contribute in a way that brings you satisfaction. That way at least one (and probably more) people will be happy! For many of us who tinker a little deeper "than just building a box", we had no midibox (or maybe not even midi) as a context for our learning. Yet we did, and thats because electronics is inherently fascinating. Especially when there is another creative agenda (for us, music) driving it. What I'm saying is that doesnt matter what the application is when learning the art. When the art starts to jell in the mind then it can be applied very fruitfully. What I'm saying is there are other places (very many places) that deal with the art of PIC assembler or basic electronics. If you feel moved to create a wholly midibox context for learning basic electronics and programming then go for it, but I think it may actually service a very small subset of the people that visit this place. One approach that could be taken (that gets used frequently on the internet) is to make a document containing links to sites all over the web that each contribute towards the body of knowledge with a few sentences that direct the user as to why the resource is useful. This kind of contribution is most welcome at the WIKI and would be a handy way of documenting your jouney as you go. cheers

500mcd would be >30 times brighter than what youve tried. The really intense ones tend to have a narrow projection angle which might not be so good if these are for a backlight. I reckon 100 to 150mcd with 60degree view angle ( or similar) might be worth a try.

no, but there are gazillions of 5V and 12V supplies courtesy of the computer industry, and very cheap if you look in the surplus and secondhand/ recycled market. Then simply use a three terminal regulator (7809) to provide 9V from the 12V rail. If its a low power circuit (which I suppose is what your talking about re SID) then a 12VDC plug pack could feed 5V and 9V regulator ICs.

latency issues with airbourne fireworks must play havoch with tight rhythms, I would suppose.

Hi Nikolai, Those mouser linear power supplies are an extremely expensive solution (and heavy). Better to source a surplus or second hand computer smps. (extremely cheap!) cheers

hi, its at www.uCApps.de look under MBHP core module. Its in pdf format and very clear and understandable. cheers

hi, its a brilliant product concept, probably unique (up until now, that is) and for that reason I expect that one of these switches costs as much as parts for a whole midibox costs. ;) One complaint I would have, is that it is not possible to read the state of the switch over I2C. You can read the serial number of each switch but not wether it is pressed. To do this you need another interface to monitor the switch contacts. Also the application shows multplexed clock and data lines, requiring many I/O's. It seems that there is no software unit address as there is with other kinds of I2C devices.(see MIOS bankstick for example of this, you can have multiple eeproms attached to the same I2C bus). It would have been better if each keyswitch had a unique address fixed at manufacture time. This way it would be possible to wire as many switches as you want with a single four wire bus:+5V,0V,CLK,DAT. So to summerise: Fantastic concept :D unfortunate digital interface implementation :-/ may be expensive ??? cheers!

quick answer is no, the monolithic ceramics mounted *close* across the output of voltage regulator ICs perform filtering at very high frequencies which is essential for long term stability of the voltage regulator. Electrolytic capacitors "dry out" over time (measured in months and years) resulting deteriorated high frequency performance (although they can still hold a charge and are still useful for low frequencies). Yes, parallel "ideal" capacitors add, but real capacitors are never "ideal" and the importance of resistance, inductance and leakage resistance depends on the specific application.

mb, did you do this test with Mackie Control or Generic Remote protocol? There are threads on both Mackie and Cubase forums talking about "flashing disco lights" with cubase and Mackie Conttrol protocol. It also seems that Steinberg fixed it with SX3.

I'm not sure how midi tracks relate to the control surface. They have a meter which is triggered by velocity in Cubase. If a channel strip in the control surface is controlling a midi track then I guess the LED meter would move accordingly.

hi, I'm still trying to work out answers to these questions but I think I can be certain about this. The cubase mackie control documentation mentions a mode whereby the metering is displayed on the LCD. This implies that the level meter info is fed to the control surface in mackie control mode, it is simply a case of displaying it. The mackie HUI has a LED meter for each track but I think the MIDIbox LC in mackie mode uses the Mackie Control protocol (not mackie HUI). cheers

While there are certainly penty of these chips on old cards in recycler's wharehouses etc, the handling involved increases the price. The idea that tubes of these chips exist as surplus stock in component resellers inventories is interesting. Maybe they exist elsewhere, as well?

hi, Info on the tascam site indicates that the FW-1884 has both Mackie HUI and Mackie control modes, giving it Steinberg (amongst others) compatability. The protocol document is the FW-1884 native mode protocol. Unfortunately Cubase does not have native mode support for this console, otherwise it would be worth thinking about implementing a "FW-1884 clone" as it seems to be a fully featured unit. cheers

hi, I'm planning a future project and I've been searching posts and a few questions are still unresolved (in my head): Is the Mackie mode of midibox LC like a) Mackie HUI? b) Mackie Control? c) Mackie Control universal? I am trying to understand the capabilities of the protocol and its implementation in MB LC. Does the Mackie protocol exist in documentation? Are there any implications of making a double/triple version of MBLC (16 or 24 MF's) for use with Mackie mode? The Mackie control has a 9th Fader, so is there a way of dealing with this (say encoder?) I hope this isn't covering 'old ground' too much.. Anyhow, thanks for any comments. cheers

hi, I think to mount the DIN externally with fewer wires to connect is the way to go also. Of course the remote DIN will be the last in the chain of DIN's. My advice would be to use a cable with a ground sheild which should be the case with a midi cable. Second, be very carefull with the pinning of the connector to make sure the midibox ground ends up connected to the sheild of the cable. Also make sure that the pin designations result in the situation that if a MIDI device accidentally gets connected to this expansion port it does not damage the device be it a MIDI out or MIDI in. This can be acheived by looking at the core as typical circuit (for MIDI out and MIDI in) and trace what would get connected to what in the event that you or someone else should accidentally connect it to your expansion port. Just make sure that what results could not damage anything. Also I would connect a few decoupling capacitors (100nF mono ceramic) across the 5V rail of the DIN board. This is simply standard electronic engineering practice especially important when the DIN board is a much greater distance from the core than it normally would be. It may also provide some static protection my reducing the power rail impedance when the the box is disconnected. Just a few easy precautions to take, like I said standard practice, and you'll be fine. cheers

hi all, Don't forget to include the effect of LED forward voltage drop in your current calculation. It means that less current is drawn than what you have indicated. typical values: standard red: 1.2 to 1.5V hi intesity red: 2.0V blue, white:3.2 to 4.0V So for a standard led (probably what your using S_R): (5-1.5)/220 = 0.016 = 16mA I had another look at the schematic. Mobius' suggestion is ideal: All "clip" leds are sourced through R28 which is driven through D4. Therefor you should replicate the line which connects the annodes of the "clip" leds. Do this by connecting another resistor (call it R28a ) to driver output of D4 (IC side of R28), the other side of this resitor is the common anode line of the row of your extra "clip" leds. There will be virtually no interaction between the two sets of leds in this configuration. This means you can have different led types and brightness settings. I suggest a high intensity 3mm led for your local "clip" indicator. With 330R for R28a this means (5-2)/330 = 0.009 = 9mA 16+9=25mA total for output D4 (within spec!). I agree that setting and balancing the percieved brightness is subjective and needs to be experimented with once you have it built. After all there are only 12 (+1) resistors that set the brightness for the entire row of meters. I am building an LC over my holiday season and I think this is an interesting idea to incorporate. Another I idea is to have a meter with fewer leds (say 4) by coupling the cathode common lines with diodes. this would have the interesting effect of modulating the brightness of the leading led segment as the input level changes! cheers

hi, the thing to do when running leds off a common source is for each led that is in parallel to have its own resistor. This stops one from being brighter than the other. The only problem would be that these "clipping" leds would be duller than the rest on the meter. solution: use a high intensity led for both the "clipping" leds, each with their own resistor wired in series. You will need to experiment with the resistor value to match the relative brightness with rest of the meter. My experience with high intensity leds is that they are many,many times brighter than standard leds. cheers

hi Jack, great link. Its seems FPGA for DIY really is here! This technology really fills a gap where h/w interfacing requirements and speed proclude uControllers. Also the softcore processor is really interesting. It seems the device necessary to support it may be a bit expensive at the moment. There are some really affordable starter kits there. cheers

More info and data sheet here: http://members.chello.nl/h.otten/vortexion.htm see YMF262 and datasheet.

This family of chips OPL3 etc were on all of the "Soundblaster compatable" soundcards right up until the SB AWE. This means early to right through to late 1990's. There were many millions produced. These should be easy to find at second hand computer markets and cheap.

Those old yamaha FM chips are mad! especially if you write to the registers at high speed with mutating values! They have plenty of multi timbral polyphony for big sounds as well.