well i’m really not sure about being in the right section here…
i’d like (in the future when i’ll have some working modules) put some of them (like SID, SEQ, FM, AY…)together in one keyboard, preferably DIY.
i’ve seen the question for a MB based midikeyboard answered several times with the advice to go for a cheap one (e.g. ebay) and put in there the needed MB hardware (because it’s cheaper than doing it with MB)
on the other hand there’s QBAS’ scan matrix, even with velocity (would be a good occasion to learn a lot).
furthermore some people have built some very nice keyboard controllers (Futureman, reboot).
i know i could just buy a doepfer CTM64 for ~EUR99.- but this wouldn’t be DIY.
so my question: is it really so hard to do for a beginner and will it really be much much more expensive than slaughtering an old DX or CZ that it would outweigh the fun of building my own? (it’s no problem if it takes months…)
I´m still in the process of doing that. But since there are some other projects to manage - this one had to wait. My MB-Sid should get a 37 key-keyboard and a pitch and modulation wheel. And some more controls because it´s a little bit underdressed
This is the material I want to work with for the keyboard:
A Dr Boehm three-octave keyboard (have shortened a 49 keyboard by 12 keys-coz they were partly broken).
A Fatar pitch and modulation wheel.
A MB-core with 18F452
Yesterday I´ve started some attempts to run the shortened octave with a fatar electronic without velocity. But I need to change my circuit first and have to add an inverter to the diode-matrix. Because my veroboardselfbuildpcb has open and close contacts for make and break instead of close and close ones like an original fatar keyboard.
Ok- I could also use the fatar electronic - but than I wouldn´t learn anything! I will only use it to get the compatibility to modern matrix keyboards.
i’d like to use a keyboard i once salvaged from an old 70ies Philips Philicorda. one side has a pcb with the resistors. the other side has for every key 5 or 6 very thin brazen tongues which open (each tongue) a contact and then close another as long as a key is pressed. it has 10 or 11 parallel contact rails (metal bars surrounded with sth like rubber with graphite)
KEY DOWN
||
||
1st bar O /
2nd bar O BRASS TONGUE
:
:
i do not know the exact number of contacts for i’m not at home atm (therefore the sketch instead a pic). but it’s even possible that some contacts close faster than others (hope).
when i replace those graphite-rubber bars with 1.5qmm solid copper wires (easy to do, the bars run through plastic holes) i could switch e.g. sth to ground by pressing a key. that should work, i used the same (just reduced to 2 oct) for a CV keyboard, the copper wire works fine.
anyway i’d prefer such a solution to buying that doepfer controller, as you say, i would not learn anything…
(when i’m there again i’ll make a pic of the keyboard)
An analog keyboard might not be the best solution there is - maybe you should try getting a matrix keyboard of the same size, they provide velocity sensing and sometimes even aftertouch.
i noticed you deleted your former posts, but trying to bookmark your thread i found out i had it already there.
the way you built your keyboard reminds me a lot of how mine functions too, it’s a shame that i do not have a photo right now. i’m very interested in how you solve the problems.
lucem: very interesting video, again ;) i don’t know much about the fatar until now and which features they provide (will have a look at them). but i always thought every key to have 2 tactile switches arranged in a scan matrix to get the velocity from.
as far as i can see there should be no big difference to mine (after replacing the strange graphite sticks with a copper wire) except that i can have more switches that way; given, that some close reliably faster than others, which i’ll have to find out.
but even if this is not happening without further mods i just could position one copper wire a bit higher (should even work with hot glue).
but of course it may easily be that i’m missing something important here. but if it is possible i’d like to do it myself rather than buying a prefab keyboard controller.
i’ll try to find & learn more about scan matrices in the next time, especially about QBAS’ and see which exact project i will actually need for this…
Seems I misread your previous post somehow, I was really convinced you had one of those really old-style analog resistor-ladder keyboards…
no no you were right, i just removed the resistor ladder. i shortened it to 2 oct and made a little cv keyboard. the resistor ladder had been substituted by trimmers (spindeltrimmer) because of the non linear behaviour of the vco (it was meant for a tube synth).
but today i had my father take me some pics of the keyboard i’m planning to use (i’ll have to wait a few hours to be able to put them here because i’m still in some other mass upload) and it turned out to be a bit different to the one i had used for the cv keyboard back then:
this one has no graphite bars, just again several brass wires per key (which i already disconnected from their resistor ladder pcb) as well as “some 4 or 5 wires that come out from the side”.
so i assume there must be some switches already integrated in that keyboard (i took apart 2 old philips organs actually). and i think i’ll have to wait till i’m there to take some measurements to see how those keys work.
I´ve deleted the posts because my statement that the fatar electronic “definitifly doesn´t work” wasn´t correct - it had partially to do with the order of the contacts at the micromatch adapter.
I must wait for the inverters from farnell before I can say more. I need some other parts from them too for din and dout modules for my sid and for the connection of the keyboard-scan-matrix. I will do the order at the weekend.
But I think if you don´t have 88 keys instead 37 or 49 it won´t be a problem to code a delay into the core´s fimware that will solve this problem and doesn´t touch the playability.
As I see in the pictures of your keyboard you have more than one pair of “Sammelschienen” so if you don´t have to build them up it could be simpler to work with close/close double contacts.
But the fixing of the diodes on a breadboard and/or the “freeairwiring” could bring you some “funny problems”.
sammelschienen: i’m curious to see how these keys function because there are actually no bars (sammelschienen). when i’m at home i’ll also post a pic of the other small cv kbd which has them.
the brass wires on the picture don’t move, i have cut them off a resistor ladder pcb that went all along the whole length of the keyboard.
and if it is possible to use that kbd i intend to wire them just as they are now on veroboard and do all necessary scan matrix connections (diodes etc) on that board.
so i hope that i will be able to use it.
at the moment i think that i might keep it even if it is not possible to obtain velocity response with this one.
upps - thought because of the parallelity of the wires that there must be more than one pair of Ruhesammelschiene=Sleepingbar? 8) und Arbeitssammelschiene=Workingbar? 8)
This is the way it works in Boehm-analog-organs from the seventies:
KEY DOWN
||
||
1st bar O /
2nd bar O || 1 BRASS TONGUE to frequency divider 1
3rd bar O /
4th bar O || 2 BRASS TONGUE to frequency divider 2
yes that’s how i expected it. the other kbd has it that way. the bars are in the front of the keyboard and the pcb on the back. and i thought this one would be the same, but as i got the photos i was surprised that there are no bars at all.
perhaps this one was from the 2nd organ and it has a different technique ???
i think i’ll have to wait until i can measure it to see how (or if) it is working.
after studying qbas´ sm_16x16_vel, it seems to be easier without the fatar-electronic and to connect a core with an adapted-scan-matrix to the keyboard, because inverting of the signal in the software is less time sensitive :D than doing it in hardware (finding right inverters, adding 5V to the scan-pcb etc.).
Did you had a look at the sourcecode? I´m not sure where to change it for an 8 by 8 matrix and where to insert the inverting for the Rueteilsammelschiene/sleepingpartbar.
I think there is not such a great difference as you can see in the gif it is like 16 switches organised as 8 pairs but one of each pair opens and the other closes when active.
… it could be simpler to work with close/close double contacts.
are there any special switches for scan matrices (close/close double contacts) which e.g. provide exactly the same distance between the contacts or is it recommended to use pairs of the well known tactile switches, mounted on breadboard?
I think most of the more modern keyboards have contacts that are made of rubber (like in simple modern computer-keyboards) with a distance of ca. 7-15 mm between one pair, take a look here –>
I have two old keyboard with bars organised in 8th or 9th as scan-matrix (Crumar Bit Mmk and Dynacord ADS-K) the ADS-K has a very good velocity-response and is halfweighted - never seen a better plastic-keybed - they both have a distance of 2 mm between the bars.
i also have a philicorda i want to midify. i found it on my work a few days ago. i have built a mb-sid before, but i have no clue where to start on this project. the philicorda is in good physical shape, but is non-working. i still havent had the time to open it up.
anyhow.. im watching this thread wioth great interest. if im getting this to work someday, my plan is to expand my sid to 8 chips and house it in the philicorda casing. btw. mine only has one “row” of keys and is quite compact.
