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John_W._Couvillon

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Everything posted by John_W._Couvillon

  1. Duggle, Back to our original discussiion of the position of ULN outputs and initialization of the shift registers on startup, If stops are on when the organ is turned on, they are immediately cancelled when jOrgan come on. Boot sequence is midibox cores, ubuntu, the soundengine, then jOrgan, and lastly the disposition. jOrgan sends out a note off message to all off magnets, whether they are on or not. My 12 volt power supply is a converted computer PS which is only rated for 10 amperes at 12vdc, and if it is on during boot up, it immediately trips out when the jOrgan disposition b
  2. Duggle, Pete, Take a look at the attached sketch. As long as the only point of connection between the two loops is the new ground lug that i show on the DOUT pcb, the high current loop involving the 12vdc PS, magnet coil and driver on the ULN and the 5vdc loop though the I/o cabling should remain separate. When the ULN conducts the voltage from pin 9 (gnd) to any of the output pins drops to less then 1 volt and the current from pin 9 to any one of the output pin goes up to 200 - 300ma. Pin 9 on the ULN must be connected to pin 8 on the 595 which is at ground plane potential, however the c
  3. Duggle. The current path as you describe it is accurate! Looking at the two main devices, the 8bit core and LPC -- The 8bit core uses a wall wart, but the core has its own rectifier and regulator, the -5v side being grounded to the core ground plane. The LPC accepts 5vdc fromt he USB connectiion, but also has its own power supply, with grounded negative. Each train of I/O is powered through the 5/c i/o cable interconnecting the DINS snd DOUTs. if there were no ULN2803 drivers there would be no need for additional 12vdc PSU, or additional common ground point. Adding the ULN Drivers on t
  4. Pete, you are correct on the J1/j2 issue of not continuing some of the DIN wiring past j2. Since i did not intend any DINS beyond that point, and since all bu the SI and SO pins on j2 are duplicated for Dout and DIN I used only a 5 pin connector. Also involved in this project are quite a few old DIN4X and DOUT4X boards which have been around since i built my first Virtual instrument with revision 0 of SMASHTV pcbs. The DOUT4X I am having the problem with is a modified DOUT which pre-dates SMASH's revision of the board to accept the ULN2803, just guessing i would say 2003 or so. So thi
  5. Duggle, That sounds good, but would require a total new PCB design with new PCB's for 64 sams, not to mention the cost of the nchannel mosfets, even in a quantity of 100. There is one commercial line of driver boards using the 74HC595 which drives simple 2n222 single transistor drivers. thats 128 transistors, but they are cheap. for the time being, SMASH TV's pcbs are the best value going. My current problem (different thread) deals with grounding issues when using a 12vdc PS for the SAMS magnets. The 28ga ribbon cable ground conductor that loops through the DOUT4X pcbs was never in
  6. Pete, The ic's involved with the proximity issue are on the DOUT4X that is down stream from the two matrix boards. you say floating input pins, but the only input pins feeding into the LPC are in the 4 matricies, (three keyboards and SAMS reed contacts) inputs. could it be an open circuit in one of the Matricies. I haven't noticed any notes not playing, or pistons not working. Would a lose connection or bad solder joint on an input pin on the 595 shift register cause what we are seeing? i'll touch my soldering iron to all the input pins on the 595's tomorrow. All the other inputs of wh
  7. pete, As of today, all SAMS work with the jOrgan either by picking with the mouse on the desktop, or by using a piston, with exception of the last addition to the DOUT train that is connected to the LPC. specifically it drives all but 3 of the SAMS on the pedal. This particular DOUT4X is the one where i am only useing 16 douts, Two uln2803s are not installed. Without the last DOUT4x plugged in to the 5/c LPC chain, everything works. When I plug in the last DOUT4X, initially the SAMS tied to it are not responding to the screen picks or pistons. now the strange part, if I put my finger
  8. Duggle, Ok, i see your point. i am probably miss interpreting the notes on the max ratings table (motorola Datasheet) it says MAXImUM RATING (Ta=25deg, C, and rating apply to any on device in the package, unless otherwise noted) Below the table it says: Do not exceed maximum current limit per driver. If you are running SAMS with 30 -40 ohm coils, thats 300 - 400ma each, connecting 4 sams to one 2803 means there is a possibility that a gen cancel will cause 4 off coils to be energized at the same time, for .5 sec. if i understand you accurately, it is allowable to have all
  9. Duggle, The 5841 appears to contain the equivalent of both the 74hc595 and the uln2803. From an application point of view, using the 5841 the DOUT4X would need only 4 ic's on the pcb rather then 8. Actually the 5841 is used on a popular brand of SAMS driver. Look closely at the datasheet, only one of the 8 outputs can carry the 500ma at a time. The ic cannot carry all 8 outputs at capacity.
  10. Pete, As for the pin10 spike, it could be a problem as i assumed wrongly that there was minimum current flow, and the connectiion from the pin to 12vdc is no more then 26-28ga. As for the SAMS, i am using the sAMS extension in jorgan which utilizes the reed switch on the SAM in the time delay process where by the pulse to the magnet lasts for only 500 ms (adjustable). I have not noticed any problem therein. Srr the attached block diagram Organ block Diagram - Ground.bmp
  11. Is it possible to substitute a MIC5841 8bit Serial-input latched Driver for the 74HC696/ULN2803 pair in the typical combo for driving magnets, excluding the current DOUT pcb design.. The 5841 will allow 4 outputs on (200ma @12vdc) at 70 deg. c ambient for an 86% duty cycle, , or 100% duty cycle for 3 outputs on at 70 deg. c ambient. In an application using one 8 bit driver package to serve 4 SAMS ( 4 on magnets and 4 off magnets) where max condition would be 4 outputs at capacity per 8 bit driver. As i understand the ULN2803 spec, only one of the 8 outputs can be at capacity at the same
  12. Pete, TK, Please feel free to move this thread to Design concepts or someother topic. I will install the revised grounding including the LPC and the core 8, test it then report back. if you have more thoughts in the meantime, please post them. i am in the late stages of construction on the console, and i hate to remove working systems, with the allways preasent possibility of inserting new issues. In general though, IMHO, I have implemented the DIN, DOUT. and matrix IO cards within the posted guidelines. How should I have done it to avoid this problem, including the grounding issue?
  13. Pete, You are just full of good news! but tell me more, Please you said: "Something else that worries me is that you have a DIO-Matrix board between the LPC17 and your Dout chain. It so happens that just before reading the Din chain, the shift registers are loaded with the RC strobe signal. This same signal also strobes the Dout shift registers into the output holding registers. So when the outputs are changed to the SAM's, the input shift registers are being loaded at the same time. Could there be noise getting into the Din chain of the matrix board?" Ok - So what is the solutiion
  14. Pete, Thanks for the explanations. Finding a place on the LPC to connect a ground pad is difficult - any suggestions? Bare in mind that all the pcb's are firmly attached to a back plane. An underlying problem that may be connected is that when the J1/j2 jumper is plugged in to the last DOUT4x, multiple SAMS begin turning on and off randomly. Johnc
  15. Pete, Currently, the LPC is USB powered from the Artisan sound engine computer which is running jorgan. The SE computer boots up in linux ubuntu which takes a 10-15 seconds after powwer is applied, After Ubuntu is loaded jorgan auto boots up in to the disposition. since the Soundengine, 12vdc supply,, 5vdc supply for the core 8 all come on at the same time as the computer, I would have to say that the 12vdc is applied long before the shift register chain is innitialized. this is definitely something that is new to me. since I have a core 8 with DOUTS driving SAMS also i suspect the sa
  16. Thorsten, Questiion: The order of MIO and DOUT PCBs cards and jumpers is LPC to matrix pcbs first in line then the 3 DOUT4X PCBs, Using ribbon cable and connectors makes the Vs terminals inaccessible. Can I just drill a hole in the ground plane on the DOUTS, install a pin connector with soldered ground lead? Question: with the core 8 Dout Chain, Is only one connectiion from Vs on J1 of the first DOUT to the system ground sufficient. The existing interconnecting jumpers are 24Ga copper, 0.5 inch long, soldered, J2 to J1 inbetween each card. Would it harm to install a larger ga ground
  17. Thorsten, Forum, Currently, I have active, an LPC-17 running 4 (8x8) matricies, 3 scaning keyboards, one scanning pistons, and 10 additional dout stages in 3 DOUT4x pcbs. The 10 stages of DOUT drive various SAMS on the console which operate at 12vdc from a stand alone 12 volt powersupply. The LPC is USB powered from a PC running jorgan. in additiion, there is an 8bit core, fully loaded, 4 DIN4X and 4 DOUT4x connected to the LPC router, and powered by a 9vdc wall wart. I am running midio128 Ver. 3 my concern revolves around the power supply interconnection on the ground side. All of t
  18. Kpete, Great stuff! I knew that there must be something out there! Thanks! Johnc
  19. Pete, Technobreath; yes you are correct, however I have added several DOUTs to the two matix pcbs that are feed by my LPC17. the ULN2803's feed the magnets on 32 SAMS and overheat for no apparent , obvious ,reason. Now i have a pile of ULN's and don't know if they are good or bad. I hesitate to plug a questionable chip into a working circuit. Yes the ULN's are cheap, but just the same. Thanks Johnc
  20. Forum, I'm having circuit problems in the new matrix pcb. Replacing the chips after each test is getting expensive. Does anyone know of a test rig, DIY or commercial that could be used to checkon the viability of a ULN2803. thanks.
  21. CSC, So you have the 220 ohm resistors in parallel with the diodes? Do you have a schematic of your circuitry? Thanks, johnc
  22. Thanks for the input. The DIN is an older one and I don't think that it has bypas caps. I'll check it out.
  23. Midio128, ver. 3, LPC17, using three matrices for keyboard encoding. In connecting the DOUT through the keyboard contact and diode to the DIN, the series 220ohm resistor usually on the DOUT has been eliminated. with this arrangement, I seem to be losing DIN 74HC165 chips. Pressing a key brings the correct note, plus others. Changing the DIN chips corrects the problem. Am I just paranoid, or is there an inherent problem with the circuit arrangement? Johnc
  24. Tim, no Sweat. you do a great job. I particularly like the LPC board. it is a super board, and works great for me. I am involved with several pipe organ situations involving electronic components by Syndyne, Artisan and others, and don't find any of them superior to the midibox modules. The LPC has the capability of toping any of them with a bit more custom programming especially in the Combination action area. With that code added to the midio128 ver 3., you could compete with any of the commercial products. Keep up the good work. Johnc
  25. hi Tim, So you are ahead of the game. Thats great! no offense intended. Please forgive if i offended you. So the box connectors can fit with the off the shelf pcb's, with as you say some shaving. We did that with fitting the ULN2803 chips on the DOUT card as you remember. I am still using those modified DOUT4X pcbs. not the most attractive, but they work. I well understand your point about costs, etc., but I also remember the revisied pcbs to add the ULN chips to the DOUT cards. The adjustment doesn't technically change the card, but lowers the probability that the connectors go on back
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