John_W._Couvillon

Shum, Thanks for the detailed explanation. I am satisfied that paralleling outputs on the ULN2803A is acceptable when done within the 8 outputs of a single chip, with careful attention to grounding as stated on other replys. However, I am not so sure that paralleling outputs on different chips is equally ok. This condition is more the problem for me then within a single ship. My pipe organ output relay consists of midipox cores and digital output drivers, driving magnets. Each core supports 128 driver outputs, hence 128 pipes or roughly 2 ranks of pipes. Some of my ranks are incomplete, i.e. the open diapason stops at tenor c, C3 so I would like to play the 8' octave of the Bourdon when the open diapason plays. That means that the 12 pipe magnets of the 8' Bourdon are driven from the open diapason drivers when the open diapason plays, and are driven from the 16' Bourdon drivers when the 16' bourdon plays. So the output drivers of two different DOUT cards are tied together to the magnet coils. Not only are the outputs on different uln2803's, the uln2803's are on different DOUT cards, connected to different Cores. There are 3 cores functioning as mididecoders, and each core supports 4 DOUT cards. A little more info. I use only one 12vdc source for all magnet supplies, and the grounds of all 5vdc ps's are tied together and to the 12vdc- of the magnet PS. Johnc

XPA, Trevor: Problem comes with paralleling between adjacent uln2803's. Not within one uln2803. I agree with your grounding suggestion as that is how my setup is wired, but that has not helped solve the problem Trevor, so you are suggesting to dedicate one 8 output uln2803 per note. So you could drive the note from up to 8 different sources. You could also do one note with 4 outputs, 2 notes per chip, or even 2 outputs, 4 notes per chip depending on how many different ranks would use the same notes. That would keep the paralleling within the uln2803. I must agree, using a diode matrix would be more economical, using all 8 outputs for one note. Johnc

Trevor, Don't quite follow your comment. About the ULN, all 8 of the outputs on each chip drive magnets. Are you suggesting using one 8 channel ULN2803 for each note? Yes, you are correct, jOrgan can do all the unification, and will. Actually though, This is not unification per se. For example, if the 8' octave of the bourdon needs to play as part of the Bourdon and also the tibia, the magnet for each note in the 8' octave must have dual inputs such that if the Bourdon stop is pulled, the 8' octave plays with the Bourdon, or if the 8' tibia stop is pulled, it will also play with the tibia. That means having two ULN2803 outpus driving the same magnet. With jOrgan, the unification is within the full 8' or 16' rank. If I am wrong, someone please step in here. Two alternate approaches come to mind: 1. Do the paralleling at the TTL level inbetween the 74HC595 on the dout chip and the ULN2803. Again, anyone with hardware savey, please jump in here. 2. Do the paralleling with the .ini file in the midio128 by keying the same outputs from different ranks. In the .Ini file, you specify all the midi data necessary to have output on each pin. If you repeat the channel no., note, and message type for each rank that a particular octave must play, it may work. Any comments. Johnc

Hey Doc, Check the attached schematic. This is what I am considering. However, I am concerned. In this arrangement, with no inputs to the ULN 2803, the output is high so the voltage at the magnet connection with the diode will be near 12vdc. with an input to the uln, the output goes to essentially 0vdc, so the full 12vdc drops across the magnet coil. That means that the diode on the other uln has some small voltage on one side( the voltage across the conducting uln) and whatever voltage the uln ouput pin on the other uln has when not conducting. Would it be possible to put a pull up resistor on the ULN ouput pin to lift it to say 5vdc when not conducting to be sure that the diode is off. As a second option for paralleling. Since the outputs from the Din Shift register (74H595) is TTL level, would it work to drive one ULN inputs from two shift register output pins. Anyone who has an opinion please jump in. Johnc

Gentlemen, A theatre pipe organ is highly unified. That means that one or more octaves of pipes can play with more then one rank. This allows for much fewer pipes in the same ranges, and allows for combinations of ranks to create new ranks. In the old days, with mechanical relays it was not a problem to just tie the relay contacts together and to the pipe magnet so any rank could play the note. With the ULN2803 driver chips, there seems to be a problem with this approach which causes failure of the outputs. With two outputs tied ogether, for example, to play middle C7 from the diapason or flute, it is not know when the failure occurs; when one putput is conducting, when one output is conducting and a second begins to conduct, or when an output turns off while the other is still conducting. In any event, The problem really impacts the application of the DOUT configuration with the ULN2803s in place. Would diodes placed between the ULNs output and the tie point eliminate the problem? Does anyone have experience with the ULN2984 8 channel, source drivers? Johnc

eionmidi, check out the link on my reply above to your post concerning douts. The link shows the connections to one ULN chip. I have added some diodes on the schematic to prevent any cross interference when more then one ULN drives the magnet. The diodes are not necessary, normally,and the magnet would be connected to one ULN. Johnc

JIm, You can do it all with the midio128, and yes, all from SMASHTV. There is not one overall kit for the midio128. It consists of a core module, digital in module and digital out modules, each available as a kit from Smash, running the midio128 application software from MBHP. My organ is in transition from a two manual midified console with PC running jOrgan and three ranks of pipe, to a final configuration with features much as you describe, and 5 ranks of pipes. In my view, midibox cores and I/O cares is the way to go on the hardware, and jOrgan is the way to go on the VTO side. jOrgan ver. 3.0 can be programmed to drive SAMS without any problem, although it takes to independent outputs for each SAM, in addition to the stop input contact. Needless to say that adds a great deal of outputs to the unit. Good luck on your project, Johnc

Eion. With 4 cores you could have 128 douts per core which is in excess of 400 outputs. To review. When the cores are daisy chained and midi merger is activated, the incoming midi message will go through all 4 cores. When you setup the .ini files for each core, you define which incoming midimessage will activate each output pin on the douts for each core/dout group. the setup includes the type message, i.e. note on/note off etc., the midi channel and the midi note. So thats message type, midi channel, midi note. You can assign one midi channel to each output pin on core 1, a different channel to the outputs on core 2 and so on. So if dout pin 12 on core 4 was programmed to respond to a note on/note off message on channel 1, with midi note 36, a midi message sent from the pc would pass through cores 1,2,3 without activating any outputs until it reached core 4. With midio128, you can even mix up the channels withing an individual core ini file. As long as there are no duplicates, only one of the dout pins will be activated at a time. if you use all 15 channels with 61 pipes per rank, two ranks per midio128/core you could run 30 ranks of pipes, or a combination of stops, pistons, pipe magnets, swell pedal, etc. This explanation is brief, but hopefully understandable. Good Luck Johnc

dionmidi, You are correct, provided that you have midi connectors on the cores and you have activated the midi merge on the midio128 ini file, and all the PICs have different id numbers. Use short midi cables and daisy chain. The midi in on the first core goes to the midi out on the computer or source device, then the midi out on the first core connects to the midi in on the second core and so on. Works great! I am also in the process of applying SAMS to my organ with the same methodology as you describe. What pc software will you be using? Johnc

Eionmidi, anybody Just happens I have a question concerning driving pipe magnets with the ULN2803 on the DOUT card, so I will add my question to yours. At times, it is desired to drive two or more magnets from one ULN output combining two pipe ranks. In the past, this arrangement has caused problems, as one output conducting and the other output in the high impedence state has caused failure of the output in the high impedence state. Has anyone else experienced this? I propose to put two diodes in the circuit as shown on http://www.esnips.com/doc/d820e2bc-b950-4a22-bbeb-685ec2047d1a/PARALLEL-ULN-OUTPUTS-DRIVING-A-MAGNET. Hope the link works. Any comments, anybody? Johnc

Trevor, Assuming that you PIC came from SMASHTV with MIOS pre-loaded, your next step is to load the application program, probably midio128, and then load the customized .ini file. If your PIC has only the bootloader installed, you will also have to load MIOS. Do remember that the PIC id for your second PIC must be different from the one you will connect too. Johnc

Trevor, There are many who have followed this thread and are interested in your success, in particular your experience with the ULN vs UDN situation. Do you have positive or negative ground, and which driver did you end up using. Don't forget that once you have success with a project roles get reversed. You become the "expert", and those who follow the details wanting to learn, become the "newbies". All of us have projects running, with problems to solve and sometime just reading about how and what others are doing prompts new ideas and solutions. Although we don't hear from many, there is a large group of individuals whose interest lies in "real" pipe organs as well as jOrgan and the other VTO or VCOs. Application of midibox technology is just now taking hold and it is becoming more and more evident that there are other ways to control a pipe organ then with an expensive Peterson relay. Some question I have are: 1. The Utube video was not too clear. What Software are you running on your laptop to provide the midi file that is playing? 2. The adapter interface on the floor with the blinking lights is an ethernet interface, USB adapter, USB to midi? Again, congratulations on your success! johnc

Trevor, Thats great. Congratulations! Johnc

Trevor, Now you have me confused! Can you sketch in the part of the schematic in the console? How are the keyboard contacts wired together? Is it a matrix? On each keyboard, is one side of all the key contacts connected to a common, grounded bus? Is there a power supply in the console? How is it connected? On your rough schematic, you show a line to keys with a (+) next to them. Does your console keyboard simply connect these leads to the +12 vdc side of the supply? Where in the console do the wires to from the stop switches connect? Why do you now think that you have a negative keying system? You need to do a more complete schematic. Its getting difficult to understand what you are dealing with. Johnc

Hey Trevor, Congratulations! Glad it worked. Have you tried tying the output of the driver to your relay? Keep us posted on the results. I'm glad the SMASHTV was able to get into the act, as I can see a need for being able to used either the ULN or the UDN drivers on the DOUT boards. I must admit, I did not know about the UDN driver. Just went with the recommendation on the midibox site. Probably would use the UDN chip if I were starting over. Good luck on the rest of your project. johnc

Trevor, You didn't say which pc board you were using for the DOUT. the DOUT boards I am using are early revision boards that were intended to be used with the resistors. It just so happened that the spacing of the holes was the same as a connector, so SMASHTV figured out how to cut some traces, and add some jumpers to allow installation of the ULN sockets. It worked, but as you say, not pretty. I think that I would lean toward cutting some traces, drilling some extra holes and installing jumpers from point to point on the pc board rather then lifting the pin and soldering to it. Thats my opinion. Without knowing which pc board you have, its hard to comment in detail on what you suggested. Johnc

Ttrevor, Concerning where to connect the 12vdc, Which of the DOUT cards available from Smashtv are you using? Did you substitute the socket for the ULN in lieu of the resistors? Bear in mind that the connections are different for the UDN chip and the DOUT cards made with the option for installing the ULN chip will not work with the UDN without some changes to the card. I have not examined a DOUT to confirm this, but I feel sure that thats the case. This should be checked with Smashtv before installing the UDN chip. Johnc

Trevor, On the ULN2803, the com pin connects to the positive 12 vdc supply and the driver in the chip connects the load connected to the output pin to ground. The common of all of your magnets is connected to 12vdc rather then ground. On the UDN 2981, the common or ground pin connects to ground and the 12vdc supply connects to VS on the chip. In this case, the UDN is switching DC positive voltage to the high side of the magnets. One side of all of the magnets are connected together and to connected to ground. On my system, the console is remote from the pipework and chests, so I use a core with DINS only in the console, and each key toggles the DIN input pins from 5vdc to ground. The ini file for the midio128 with the DINS is set to default, or low active state. If I ground an input pin, a note sounds. On the output side, I have another core with DOUTS in the pipe chamber (35 feet from the console)with midi cable inbetween the two cores. The [iNVERSE_OUTPUTS] in the ini file for the midio128 with the DOUTS is set to default also, or disabled to get active high on the output of the shift register. With a uln2803 connected, an active high to the input pin of the ULN2803, 0 to 5 vdc +/- and the output of the ULN goes to almost 0 volts, connecting one side of the magnet to ground, with 12vdc on the other side of the magnet. If you use the UDN in lieu of the ULN, The active high input to the UDN will produce an active high on the output, 12 vdc. With a magnet connected between the the UDN ouptut and ground, it would see +12vdc +/- and pickup. I have not used the UDN driver, but I suspect that its active high input, active high output. You said that you are getting 5vdc out of the shift register on the DOUT with no input, and 0 vdc ouput with active high input. That tells me that your ini file is set set with [iNVERSE_OUTPUTS] ENABLED, The outputs are low active, or 5vdc normally going to 0 volts with input. It should be set to the default value DISABLED. If I remember your setup, you need +12vdc to your relay to pickup your magnets, Evidently, the stop switches and keyboards on your console are switching +12vdc on and off. To duplicate this, I would think that you have to use the UDNs to provide the 12vdc drive to your relay. Johnc

Treavor, Disconnect the LCD and with the core connected to the midi in on your pc, use midiox to monitor the output of the core. If you get the usual syex string displayed you probably are ok. I don't have an LCD on my cores and rely on midiox to tell me what is going on. If you get nothing, then maybe you have a problem. In any event the next step after loading midio128, you need to configure and load the ".ini" file to configure the system. Go to the wiki and read the procedure on how to do that. The ini file is where you define what incoming midi message will activate each output pin on your dout cards. Johnc

Trevor, Thanks to Sparx I think that you have your solution. Good luck with it. Do come back and let us know how things came out. We like to hear the success stories too! Johnc

Trevor, I see Doc's point, but the cost of the Meder electronics reed relays (SIL05-1A72-71D) in the mouser catalog is $2.30 for an order of 50, $2.43 for an order of 25. The good thing is that the relays will fit directly on the dout pcboard and the contact is good for 1 ampere. See the reed relay example on the ucapps website. I would venture that the reliability of the static relay device would exceed the transistor approach with much less trouble to install, and I would suspect that the final cost would be very close. Good luck, Johnc

Trevor, Go to http://www.uCApps.de, select the midio128 on the left hand list. There is a schematic for connecting relays to the ULN2803. As mentioned earlier, I don't think it will work either thats why I recommended the reed relays. there is also a schematic for driving reed relays. Good luck,' Johnc

QBAS, Your old wiki address http://www.midibox.org/dokuwiki/doku.php?id=qbas does not work. Do you have a new link to the matrix code? I have received core and I/O kits from smashtv and will beginning assembly of the matrix with three keyboards, stops, pistons, etc., etc., and will keep you posted when ready to run the tests you recommended. Thanks, Johnc

Bill, Check out the following website, there are several good circuits to generate servo pulses; http://www.uoguelph.ca~antoon/gadgets/servo2.htm: ........servo3.htm: ......servo4.htm All of these generate pulse trains in the 1 to 2 ms range for compatibility with the typical R/C servos. You should be able to change the frequencies and pulse widths by changing component values. also google NE555 and you will find numerious sites with data concerning 555 nd 556 circuits. Johnc

Midiboxxer, Located data online for the ALPS motorized slide faders. Good stuff. the diagrams show terminals: A and B on what appears to be the motor. Term. 1 on the motor end of the device. Term. T, 2 and 3 on opposite end from motor. I suspect that A and B are for the motor. T is the tap on the slide resistor, Question: Is term. 2 the bottom of the resistor, or is 3 the bottom? Thanks, Johnc