Wilba
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Posts posted by Wilba
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Technically not a V2 wish, but TK, can you do a build of MBSID v1 for PIC18F4620? I was thinking that some people starting an MBSID now can buy a PIC18F4620 now, instead of having to upgrading later, and those with an MBSID already can upgrade their PICs now. I know some of us ;) can just recompile it with different settings, but perhaps you can do an official build that uses IIC MIDI as it will be used in V2.
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Everything I learned about power supplies comes from the net, or this forum, which had links to stuff on the net. Keywords: rectifier, regulator, filter capacitor
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After playing with 22nF on my 8580s and 6582s, I tend to like them better than 6.8nF, the only downside is I need to tweak the cutoff for the preset patches (and the depth of any envelope or LFO that modulates cutoff). I haven't tried anything higher though.
I put machine pin sockets in the filter capacitor holes so I can swap them around, and I've thought about a manual switch, and even contemplated a software controlled switch too... there's a couple of spare outputs on the shift register which could be used to drive a 4066.
As I said before, the only downside to switching over to 22nF is having to tweak all the existing patches to make them sound the same... which really isn't that much effort (especially if you have a four SID setup and can compare SIDs with different capacitors). It would be nice if 22nF became the new default (it's also the HardSID default, btw), perhaps as part of the MBSID v2, each patch can store what capacitors should be used (hint to user to flick a manual switch, or firmware can drive an electronic switch).
I'm going to run some tests with a 4066 and see if it works... :-)
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This has been explained elsewhere on the forums, but cos I'm in a benevolent mood I'll explain it again ;D
An AC voltage rating of 9v means the actual voltage will be peaking higher than +9v and lower than -9v, 9v is measured as the RMS (root mean squared). Rectifiying will turn it into a series of peaks higher than +9v, then a capacitor will average it out to a slightly lumpy 12v DC, and then the 7809 will regulate it to a very flat 9v DC.
So in general, 9v AC means it's equivalent power (i.e. you can convert it) to 9v DC.
In the optimised PSU design, the 9v DC output of the 7809 is actually 9v above the 5v DC, observe the ground of the 7809 is on the +5v DC, so it will regulate to 9v above the 5v, thus 14v DC. This is then further regulated down to 12v or 9v by a regulator on the SID PCB (7809 or 7812 or 78L09 or 78L12).
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Thanks for that pseudo-eBay feedback!
The cheap shipping is because it's charged as a letter, not a parcel.
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c0nsumer: I'm interested to know who's doing the PCB manufacture, especially your prototype ones, as I have a need to get some made. I'm thinking of using BatchPCB, but I'd like to shop around first.
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I am on a campaign to steer everyone away from Futurlec:
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You can work around the DOS limitiation in Windows by removing the protection on the COM ports... I had to do this to get IC-Prog working under XP. What I used was called TOTALIO... google found this: http://www.satellite-calculations.com/Satellite/dvb2000/how_to_install_totalio.htm
Futurlec handled my PCB order quite well, and even threw in extras which I didn't pay for (i.e. the extras left over when they did multiple copies on one bigger board). I think I am more annoyed that I HAVE to stop using them, as I really did like the range and price and now need to shop around more. Bugger.
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In the past I have suggested Futurlec was a good place to get PICs, other chips and parts you can't find in your local electronics store. Yes, they have great prices, and cheap shipping anywhere, but my last order has been a complete disaster and they now ignore my emails completely.
I ordered six "High Quality P.C.B. Mounting 6.5mm Jack" and four "6.5mm Stereo Plug to 3.5mm Stereo Socket" (among other things). The first package arrived weeks late, and was missing the jacks, although I was charged for them. After emailing, I was told they would send replacements. Weeks later, the replacements came, but only two, not six, and they weren't the "high quality" ones with chrome mounting nut, just the cheap plastic variety. I emailed again, I got a new package which contained four more sockets, still the cheap plastic variety, and one even slightly different, with a gold ring at the end.
After I emailed to complain again, I was completely ignored.
I then discover the stereo adapters, while having a 6.5mm stereo plug, actually have a 3.5mm MONO socket! This was causing me so much grief as I was trying to work out why the line in on my Audigy sound card was only recording mono! Again, my complaints have been ignored completely.
I really wish I could keep using Futurlec, as they really do have cheap parts that I can't get cheaper elsewhere, and every other order I made with them was great, but on principle I won't deal with them ever again.
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I think there are cheaper, new-old-stock chips out there, you just have to shop around.
I know you've probably factored in shipping costs, wire transfer, etc. but I think I got a much cheaper quote, like under US$5 per chip. If you want, I can dig it up for you...
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It wasn't really a suggestion... I'm no audio electronics expert at all, only quoting the SID datasheet. Perhaps someone else can suggest whether a ground plane would be better, i.e. even less noisy.
I was hoping that your experience with this PCB design would help me in my own, so I could decide whether to join the SID's ground to a ground plane or use an explicit track.
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I think this was already proposed by someone and TK said it was a lot of programming effort.
MIOS can handle two displays nicely (just add 0x80 to cursor position to write to second display), but more than two involves a lot of MIOS_LCD_TypeSet calls sprinkled everywhere.
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Good work...
It looks like the ground isn't connected to the pins... are you intending to use wires under the PCB? If so, it's a good idea, as I believe you get less noise if the SID's ground is connected directly back to the ground of the 7809 or 7812 (as per SID datasheet). I'd be interested to know what ground wiring produces the least noise (i.e. how you wire SID's ground, audio out ground, the mini-amp circuit ground, etc.)
Also, a direct connection of the +5v supply to the 7805 is recommended by the SID datasheet, maybe you should put the track from C4 straight up to C28 instead of joining the +5v track connected to the shift registers.
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That makes two of us. I heard those 6582a's and I instantly wanted some :)
So did I. Now I have too many. ;)
This topic really interests me because I really want to tweak the filter caps on the 6582... so my earlier comment about the 6582 sounding the same as the 8580 is not based on Razmo's demos, it's on first hand experience. To my ear, when both have 6.8 nF caps, they appear to have the same cutoff frequency.
I just did a very, very quick test: with the 6582 and 8580 both using 6.8nF capacitors, and a simple pulse waveform, and lowpass filter, I get the same sound out of both. If I increase the 8580's capacitors to ~22nF, I need to change its cutoff CC to be 20 higher than the 6582's cutoff to get the same sound, i.e. CC=60 on the 6582/6.8nF is the same as CC=80 on the 8580/22nF. I'm not really proving anything scientifically here, but I'm pretty confident that a 6582/6.8nF does not have the same cutoff range as an 8580/22nF. I also stick by my earlier statement that a 6582/6.8nF has the same cutoff range as an 8580/6.8nF. All the filter-modulating patches sound the same.
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The E thing is scientific notation (exponential), where the E represents "times 10 to the power of"
Oh, that E... doh! :-[
Remember that equation is taken from the 6582 data sheet. It does apparently not apply to the 8580. As hardly noone has ever seen one of those SIDs i don't think it's relevant.
I think it is relevant. Depending on which theory you believe, the 6582 is either an 8580 prototype, or a new revision of the 8580... what I know for sure is that the 6582 has a filter that works and sounds the same as the 8580, at least in my MBSID with 6.8nF ceramic caps and by my untrained ear. I should try some 22nF capacitors too, but I'm not sure what I should be listening out for, or how to measure the difference, or how much the frequency mapping between the CC value and the actual SID registers masks the real difference.
Interesting to note is that this equation together with the suggested 6.8 nF (all from the 6582 data sheet) gives about the same frequency range as the 8580 does with the recommended cap for that SID (22 nF).
Can you explain that a bit more?
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Pixels that are "on" are lit, this is PLED, there's no polarizing filter or anything, imagine an array of tiny square LEDs. The interface is standard HD44780, and there's nothing in the specs to invert it, not that I'd want to...
Even though it's totally new tech, it has a bit of old school charm, like an Apple II monochrome monitor.
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Thanks Nattgris! That's the sort of testing I'd like to do, if I had an oscilloscope (and more understanding of how filters work!)
FYI, the 6.8nF (6800pF) value appears in this datasheet:
http://www.joogn.de/b/6582.pdf
Under the pin descriptions for the filter capacitor pins...
... Normal operation of the Filter over the audio range (aproximately 20 Hz - 12 KHz) is accomplished with a value of 6800pF for C1 and C2. .... larger values of C1 and C2 could be chosen to provide more control over the bass frequencies of the Filter. The approximate maximum Cutoff Frequency of the Filter is given by:FCmax = 8.2E - 5/C
Wheren C is the capacitor value. The range of the Filter extends approximately 9 octaves below the maximum Cutoff Frequency.
Maybe someone can explain that formula to me...
I am also curious to know how the capacitors affect the filter, and would like to hear about any more tests you do!
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This is my usual logo. I designed the logo about twenty years ago, the fancy background more recently courtesy of Photoshop. Looks a lot better in its original size.
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The specs say over 10000 hours. I suppose that is a bit short... a little over a year if on 24 hours a day. Maybe my MBSID needs a screensaver! ;D
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PLED displays are the best.
at even ridiculous viewing angles too...
if only they made them in 2x40 :'(
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Good news, the supplier is replacing the 6 dead chips, so if they are tested to work perfectly I can offer these for sale. They'll be shipped air mail, so it will be a bit of a delay.
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Can all those who are getting some of these chips please read their private messages?
I am ready to ship them, but I need your PayPal email addresses to send requests for payment, and your postal addresses.
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You only need one wire, to connect the MIDI output of the master Core with the MIDI input of the slave Cores. It is NOT a typical "daisy chain"... you DO NOT want to connect the MIDI output of the slave Cores to the MIDI input of the master Core!
I use a chain of wire lengths joined together with the crimp pins that go inside a single row header connector. In this context, you don't need that black plastic header connector, as there is only one connection and you can just push the single female pin onto the male pin on the PCB. Cut three lengths of wire and join them together in a chain using the female crimp pins (two crimp pins in the middle will crimp onto two wire ends).
I also use this "chain" idea for my power wires, using two or four pin header connectors.
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Nintendo used gyroscopes and technology from Analog Devices for their revolutionary controller, and this kind of device can have *A LOT* interesting uses in the music world.
I disagree. If there really was a lot of interest in the music world, there would be more people playing theremins or using theremin-to-MIDI controllers, which have been around for ages.
My focus now has shifted to ribbon controllers instead, for the simple reason that for music, at least, some tactile feedback is better than none... ever tried actually playing a theremin?
MIDIbox SID V2 wishlist
in MIDIbox SID
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I know the 452 and 4620 are pin compatible, but I would have thought they'd have some subtle differences in code. Now where did I put that PIC programmer... it's been so long since I needed it, thanks to uploads via MIDI ;D