TheAncientOne
-
Posts
726 -
Joined
-
Last visited
-
Days Won
2
Content Type
Profiles
Forums
Blogs
Gallery
Posts posted by TheAncientOne
-
-
I've just come across this thread, and seen a few of the ideas.
First thought: MIDI is a current loop interface, specified at 5mA loop current, though often running a bit higher to give leeway for differing opto isolator input LEDs. The voltage is not really the issue.
Changing the input of the 9090 is a bodge, it works fine with other sequencers - you will only get the same problem with other devices, especially those using older optos like the CNY series.
The simplest solution to me, would be to reduce the value of the output resistors in the sequencer. Since there will always be a 220R in the input circuit of the target MIDI device, dropping the resistors at the sequencer end to 100R or 68R would get closer to the spec, and the max, shorted output current from the sequencer , (in case of a bad lead) would still be a fairly safe 16 - 25 mA. (standard short circuit current on 5V would be a round 11ma).
Oh, and if anybody is thinking of termination impedance matching: try to remember this is low KHz speed, not RF, and the lower output impedance would actually help keep the pulses square....
(added 05/11/2017)
The latest MIDI spec, (CA-033) MIDI 1.0 Electrical Specification Update [2014], suggests 33 Ohms from pin 4 to the 3.3 V rail, and 10 Ohms from the device output to pin 5. This makes for a short circuit current of 76mA, which I consider too high for safety on a microprocessor output. I think it's good practise to use an output buffer: if you are working live, a spare buffer chip can be kept in the toolkit. A spare micro module is not so easy.
Just a few thoughts anyway
Mike
-
2
-
-
I was looking at something similar, though in a more industrial design. I wanted to do 'voice cards', as eurocards, and plug them into a backplane, allowing me to break out I2C for an AOUT NG and have space for a set of my 2044 filter cards.
I intended to make a 'dumb' control surface, in a separate desktop case, and use proper CAN buffer chips to allow a longer cable between the sections. As a mark 1 version I was going to use the spare MB 6582 base board card I have to house the 4 voice PICs and their SIDs. I also thought about having separate illuminated buttons for wave selection etc., to avoid stepping through options in live use.
For now, I am still learning how to drive my MB6582, so this went on the back burner.
-
Despite being the 'Bulk buyer' and rare parts miner for this project, I didn't start building mine until last month! I did build an Adafruit kit; I got to the top of the list just after I started the bulk buys, and so got the kit and built it so I could test programmed processors, and check parts differences. I had a long layoff from electronic music work in general, due to a lot of problems in other parts of my world, but recently got back down to it.
Amusingly, following a comment above, I have just finished my MB6582, (from Wilba's original boards), bar some ventilation holes in the case, and outputs for the MBCV-NG board to drive the 2044 external filter boards.
The x0xen will be next - I've built up the power boards, and am just waiting for some multi-turn trimmers for the PSU setting - having built an Oakley TM3030, I can say with all certainty that they make setting that 5.333 Volts much easier. I am currently trying to find a local paint sprayer - i want to do the PT-10 case in silver to match the panels.
I'll blog some details when I get a few minutes.
I think I get the 'wooden spoon' prize for assembly time here!
-
I'm interested in the Tabularasa board, I'm in the UK, any idea on postage? Thanks.
Mike
-
Thanks very much Jerome - my boards were waiting when I got back yesterday. They look superb!
-
I'm with the other guys here - don't worry about my boards; have a good Christmas, and post after the rush is over.
Thanks for all your hard work.
Mike
-
No, it's not too late. Thank you very much.
When I'm back in the workshop next week, I will update the logo. It's a simple panel - I will colour print it on card, cut out the display window, then laminate it in a heavy duty 'pocket'. It will be stuck to the alloy under panel with double sided tape, (the industrial kind).
I'm still wallowing about getting the 40 column display software sorted, so it is a few weeks off being complete.
I'll post a revision once I've got it done.
Thanks again
Mike
-
Really nice work - and it's certainly made me think about using Pokono myself.
I have to do the same thing with paths for my local plasma cutting service, and they give me a better price since they don't have to re-work my CAD drawings.
-
This is a panel design mock up for a small MBSID. I had some good quality buttons, free, but in a nasty green shade. A friend suggested a blue panel, then a Ukrainian visitor said it looked like an old Russian aircraft panel, sadly he'd gone home when I though to try doing the panel in Cyrillic letters.
The display is a small format 2x40 I got a few of on ebay, by accident, (too small for a sequencer); they nicely match the buttons, so got the job. I know Thorsten did code for this format so I thought it would be a bit different.
Panel will be ink jet printed, laminated in a heavy duty film, then stuck on with High bond tape.
If anyone can correct my attempts at Russian, using bits from the the forum and an on line lexicon, I'd be glad of the help.
Any other comments welcome before I start cutting the metal.
-
An idea. Why not have a rectangular hole in the back of the case, that an 'L' shaped panel will slide into. Have back plates cut for whichever core you have, A bit like the optional sound modules for some keyboards.
-
Wow. Thanks Thorsten, that is fantastic.
I'll get on with the the CAN bus interfaces, since hardware is more of my bag anyway.
-
Hi Folks
Quite a long time since I did any serious electronics for myself; the outside world got a bit 'messy'. It's good to be back getting on with my own stuff.
I've just done the final assembly work for my MB6582, (which must give me the 'wooden spoon' prize for slowest build from the Wilba's original board bulk buy), and been doing some thinking.
I'd like to build another one for live use, with bigger, more solid control, and preferably putting the actual SID part of the unit in a 19" rack module, and having a thin, but more solid control surface near my keyboards. I bought a seond base PCB for just this reason.
What I would like to ask the programmers amongst us is this: if I put another PIC in the control surface, and used 'proper' CAN bus tranceiver chips to get the longer cable run, could I still control the four PICs in the base unit, or would I have to sacrifice one channel pair, leaving the PIC in the control surface as a 'dummy'?
Apologies in advance here - I may have asked this before, a long time ago, but can't remember when and where.
-
Thanks, I have replied in the other forum.
According to that forum, Doug says you got your refund, on the 24th of July. Is that true? If so, it might be a courtesy to post the fact that the issue has been resolved, here.
-
Just blown away by this, Hawkeye, and very salutary lesson on just how far emulated/sampled pianos still have to go, the richness and density of the sound is beautiful.
A very refreshing change too.
Brilliant.
I think I have to steal your SMD LED's idea. It gives such a good layout, and might help in my search for some buttons that my fumbly fingers can work more easily.
In fact, a though for the future - on a lot of PCB's it would be easy to use a 'combo' type pad for SMT/close pin capacitors etc. 0805 100n SMT caps are cheap and easy to fit and can make for a smoother layout. I'll do a post in a more suitable section once I've done a bit more thinking.
-
I looked into the datasheet: http://www.reichelt.de/index.html?;ACTION=7;LA=3;OPEN=0;INDEX=0;FILENAME=C200%252Ftaster.pdf;SID=11TVLbZ38AAAIAAG9MIgIec1e46ae3eb4fc2fe4e011f269170227
Indeed, the footprint doesn't match exactly with the PCB.
Instead of 0.3/0.2 it has 0.256/0.177 (resp. 6.5 / 4.5 mm -> seems that this button is optimized for metric measure system)
I don't find this so dramatic, but for the perfectionists it would be interesting to know if there are buttons with 0.3/0.2 footprint?
Best Regards, Thorsten.
It seems as if 6.5/4.5 is the industry standard for 6x6 switches. I can find a few with the vertical spacing right, (listed as 5mm), Closer fit, but not checked but they all seem too wide, (I'll have to get a few and check). My conclusion is that the KiCAD library item is simply wrong, or for an obscure make of switch. The footprint Wilba used for the MB-6582 is perfect.
The only ones I could find that should fit directly are the C&K KSA and KSL series. The advantage is that these are high quality switches, and you can buy caps for them, the disadvantage is the cost, the price from Digikey being £21.08 for 50, plus VAT. Digikey switches
This reminds me of the actuator fitting problem on the 12x12 switches - Limor Fried used a US standard for the x0xb0x, meaning you have to buy the button caps and buttons from a US supplier, when the Euro/Japanese standard is a little bit bigger, (and has a wider range of caps too!).
One bit of good news for UK builders. Rapid has The standard tact switches at both 9.5mm and 13mm height for less than £0.02 each: Tact Switches at Rapid
Another source of confusion for these is that some suppliers quote the height above the PCB, and some quote an actuator length! Rapid seem to quote overall height above the board, so choose depending on what you make your panel from.
They also have SIL sockets for mounting the LPC module. Rapid SIL sockets page
In fact, you can get most of the sequencer parts in one hit, from Rapid, and qualify for free delivery.
Edited to add Digikey reference and general tidying.
I'm guessing that a small bulk order from Digikey might get the switches to about £25 for 50, delivered in Europe, (this is just guessing at postage and palypal fees). If 8 more people want a pack of 50 (gives a couple of spares), I'll do it, though I need to check for fit, first. There is another option involving a low profile version with an actuator cap, though these come out a little more pricey - I'll do some checking, to make sure they are a possible.
-
I just picked up a slightly used Korg Kontrol 49, (the one with the full size keys). I've very happy with it, though the action is very much in the synth /organ style, not at all piano like, though it has programmable velocity curves, (it had pretty well programmable everything!). It work well with what I'm trying to do, though I am looking for a second hand Fatar 88 notes weighted keyboard for soemthign more paino like, later on.
-
Very nice piece Hawk - really enjoyed it.
-
Hi all.
Let me know if you have some Digitast's to sell (or if you know where to buy some).
My priorities:
1x Double-width (34mm), without led, black, C&K / ITT / Shadow
Alphanum wide 17mm black caps (C&K, ITT, Shadow)
2-led (or 2-holes) narrow caps+switches (13mm), any color, any brand
Labelled caps (arrows, symbols), any color, C&K / ITT/ Shadow
I'm also interested in buying batches.
RS have some - they're now made by C&K, not ITT. The problem is that RS want a stupid price, (in my opinion). RS Digitast page
The makers are here: C&K site they might have a lead to stockists.
Hope this helps
-
I can't see any practical point for adding D5, either.
I agree that dropping something like 10V on the 5V reg is not too good an idea; I just tend to use 2 transformers if the 5V rail is going to be drawing a lot of current. A slightly more involved solution is to pre-regulate with a small switch mode circuit, it doesn't have to be that accurate, and will generate far less heat.
One thing no-one seems to do for this type of gear, is fit some kind of 'power fault shut-down'. I 'll try and do some details when I have time, but on my MB6582 power supply I will be fitting a 'crowbar' to the important rails, (this is a circuit that shorts out the power supply with a big thyristor if it goes over voltage); those SIDs are way tp precious to risk a PSU accident killing them. An having ground open an olld C64 supply, there is no way i'd trust one, long term, especially not with 2 disparate rails 'stacked'.
+1 on the protection diodes.
-
Heya Prof, got any of these?
NE566
CEM3394
XR2206
XR4739
Thanks,
-Steve
I'll hvae a look. I know I can't help on the CEM's, though I do have about 12 CEM 3372's (data sheet). I only have enough XR2206's for my own use for the Thomas Henry XR VCO. I can let you have 1 or maybe 2 566's. The XR4739 is the same as the RC4739. It's a not-very-special dual low(ish) noise op amp. The only problem is the pinout. If you're using original boards then you need the original chip. If new I'd go for NE5534. Fairchild did a ua4739, which is an uncompensated version, and will need a couple of small caps adding.
A couple of tricks you probably alredy know are shown here substituting techniques. I tend to use a variant on the 'dead bug' style, on a 14 pin header and plug that in, allowing a change for the real thing if I get lucky.
I'll get back to you later when I've had a look.
-
Digging through my parts cupboard to find an what I thought were a couple of AY8910's I found a few more, so they're up for sale. They are 'pulls' from working arcade machine boards, from a time when I used to repair them.
3 off AY8910 [1 of 4 SOLD]
SOLD [2 off AY8912]
£2.50 each, carriage from the UK at cost.
PS If anyone needs any odd old chips, drop me a line. I've found everything from AMD bit-slice processor parts to Zilog Z8's, (and Z80, and even a Z8000).
-
I knew I'd kept some 8910's for synth making from my days repairing arcade machines. I set out on an expedition into the back of my storage cupboards tonight, and finally found the big box of old chips. Wow! I did keep some weird stuff. All flavours of Z80, 6510's, 286 flat packs, about 50 6116 2K RAM chips, what seems like a tin of every EPROM ever made, (really: I found 2 1702's), and finally the sound chips. I found 7 AY8910's so far, marked 'pulls from working boards', and a couple of 8912's. I've put some on the fleamarket, since I won't need them all.
Oh, and if anyone needs any other odd chips, drop me a memo, I might just have them, for instance if you have a pressing need for some MBM93419 64x9 bit bipolar static RAM - for your 1970's supercomputer or logic analyser, I have at least 10 of them!
-
Perhaps better in the "Tips and Tricks" section, but here are a couple of Perspex leaflets in PDF.
Working with Perpex - material specs
Working with Perspex - technical
There are quite a few other material data and working sheets here
-
Still for grabs
I'm definitely interested. I'm in the UK. Do you want to drop me a note of the shipping cost, and we can then work something out?
sammichsid - any way to create/edit SID files or extract their sounds?
in MIDIbox SID
Posted
Massively late to the party, but I have just been playing with the ASID player driving my MB6582, whilst laid up following a leg injury.
I got the massive SID tunes archive from
https://hvsc.de/
I noticedthat many will play fine via ASID under Windows 10, some only did the initial loop, this is probably because they are aimed at devices that directly drive the SID chip, not via SYSEX.
I wanted to get at the 'Stardust' tune from the musc for David Whittaker's legendary 'Lazy Jones', (yes, the one made famous by Zombie Ntion using it in their track 'Kernkraft 400').
I decided I needed a SID file editor, and I found this thread in the process, so I thought I'd share the one I found, here.
It looks a bit old fashioned, but works OK so far under windows 10. It is also available in PERL/TK script too.
https://www.transbyte.org/SID/SIDedit_download.html
It needs a SIDplayer and a hex editor to go with it. There are emulators etc available from the HVSC site, linked above.
Hope this is of use to people.
Wish me luck with the fileediting, this is all new territory to me
Mike