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JOHN D SMITH
Junior Member
United Kingdom
9 Posts |
 Posted - 26/11/2007 : 6:37:33 PM
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Hello fellow organ builders I am in the process of building my own
"FREELANCE" concert organ which opperates on MIDI, I am using a standard 64 output MTP-8 unit from Mr Wale I have just completed midifing a 41 note 12 bass Scandalli accordian (handed down to me by my late Father) it plays great also I have two ranks of 61 pipes (ex church organ) I have just started building a rank of 61 reed pipes .
my problem is as all these have seperate solonoids for each respective note I am worried about getting very close to the max output power of the ICs I am a bit of a novice re electronics has anyone out there got any info on a transistor curcuit to give me an output of 1 or 2 amps , I am running 15 volts
appreciate any help thanks J D
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Jim Bryan
Senior Member
USA
15 Posts |
Posted - 27/11/2007 : 09:24:33 AM
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I am also interested in this circuit.
Thank You
Jim |
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Chris Blanchard
Advanced Member
France
27 Posts |
Posted - 03/12/2007 : 10:19:12 AM
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Hello John !
If I well understand you want to drive more than 200 pipes and reeds with only one midi card ? Of course you can add circuits to get more amps but what is the interest to make playing all the sorts of pipes/reeds the same music ? You'll have the same limitation as with a book or roll ! If you put 4 JW midi cards you obtain 256 outputs on 4 midi channels (or more if you want) so you can drive each solenoid separately. If you want them to play the same at a moment you can,and if you want them to play different voices you can also ! And no more circuit needed ! For exemple my midi accordion has got 2 JW MTP8 cards (one for each hand). Try to listen this : http://www.blog4ever.com/fichierss/69227070425091442.mp3
Organ and accordion play together (one midi card for organ and 2 for accordion)
Best regards
Chris |
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JOHN D SMITH
Junior Member
United Kingdom
9 Posts |
Posted - 04/12/2007 : 09:57:57 AM
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Thanks for your help Chris my setup is at the moment at the "experimental" stage and I have already blown two output ICs mainly through trying different solonoids etc and also I have aquired a solonoid for thumping the bass drum that pulls 700 ma on 12v
I understand what you mean about splitting the midi up into different channels and will certainly do that as funds allow
thanks again J D. |
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aobg
Forum Administrator
United Kingdom
254 Posts |
Posted - 21/12/2007 : 04:06:21 AM
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Sorry for my delay in answering some of your postings and emails, this is my busiest time of the year.
I have set out 3 diagrams for you 1 for 12 volt, 1 for 15 volt, and one for 24 volt, now I have not tried them myself but have done this kind of circuit many time over the last 25 years or so working in the trade.
Now please take care. If you get this wrong you can damage your j-Omega Electronics board.
Will get round to test all the diagrams soon but I do expect them to function perfectly.
I know I should test before posting them but it will be weeks before I get chance and as this post as been waiting for a response from me or someone I thought I better post something now.
For you that would like to research how one arrives at the resistance and what kind of transistor to use this link may help
http://www.kpsec.freeuk.com/trancirc.htm
I can try to simplify it all for you but as there is a good example on calculating what components to use for this kind of diagram I thought It might be better to direct you there. Have a good look around this website there is load’s of diagrams that may be of some use in the organ world.
http://www.kpsec.freeuk.com/index.htm
This website as some useful diagrams on PSU’s
http://www.aaroncake.net/circuits/index.asp
Please note that the diode polarity and your PSU in/to your wind chest may need to be reversed.
Yours Phil Radford AOBG website & forums administrator. |
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Chris Blanchard
Advanced Member
France
27 Posts |
Posted - 31/12/2007 : 07:26:19 AM
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Hello Phil
I'm interested by circuit for I 've got a few "big" solenoids, but, it seems to me that on JW cards the common is positive and not negative as show on your draw, is'nt it?
Happy new year to everybody !
Chris |
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JOHN D SMITH
Junior Member
United Kingdom
9 Posts |
Posted - 13/01/2008 : 5:44:12 PM
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THANKS Phil
I have built this curcuit and it works ok my bass drum solonoid on 15 volts pulls 1.15 amps I mounted the transistor on a heat sink and it runs cool
Chris,s point about polarity is not realy a problem with a solonoid that is accesable you just turn the diodes round.
I seem to remember from my tec coll days that you can feed a npn transistor through a pnp one not sure how to do this I will experiment (away from my JW board) and post the results.
Thanks again its great to comunicate with fellow enthusiasts
JDS |
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aobg
Forum Administrator
United Kingdom
254 Posts |
Posted - 14/01/2008 : 03:54:39 AM
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Hi J.D.
If you need the NPN diagram let me know.
Yours Phil Radford AOBG website & forums administrator. |
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aobg
Forum Administrator
United Kingdom
254 Posts |
Posted - 14/01/2008 : 04:21:11 AM
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Hi Chris.
The outputs of the JW cards are positive so a PnP transistor will need to be used.
This will switch on the load on when the JW card output is low (0V).
Will post more on this if needed but I am trying to be brief on the above has I don’t want to over complicate anyone understanding of the j-Omega Electronics board.
Yours Phil Radford AOBG website & forums administrator. |
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john smith
Advanced Member
United Kingdom
30 Posts |
Posted - 08/02/2008 : 11:12:25 AM
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Driving multiple pipes in MIDI organs. I can offer 2 tried and tested methods as working in my Juliana 98 key for a few years now. The organ uses separate solenoids /pallet magnets for each rank of pipes.
First of all remember that the higher the voltage the more current will be drawn. I use 90 ohm coils on 15/16 volts higher voltages will also cause these smaller solenoids and coils to overheat.
I drive one or even two rank of pipes from the direct outputs of the Wale board this covers melody accompaniment and counter melody, also bass pipes with 60 ohm solenoids. For the 25 melody outputs I have added a simple two transistor circuit which gives another 1 amp capability, this should be enough for all but the very biggest organ. I just built these on vero board, the transistors shown (from Rapid electronics) are very small, cheap and do not require heat sinks, the actual type numbers are not essential just similar specs. For the percussion outputs small relays are used as I have various solenoids some taking a couple of amps. It would not be a bad idea to fit relays on all the melody outputs at least these are fairly bomb proof which is not a bad thing when you are adding things to the organ later. Always fit a low amp fuse before you even switch on for the first time, many seem to remember the fuse when only after something has blown up. All you need now is the circuit, badly drawn but this is not any circuit its a John Smith one , so you know it works !!
And your worth it !!
Driving multiple pipes in MIDI organs. I can offer 2 tried and tested methods as working in my Juliana 98 key for a few years now. The organ uses separate solenoids /pallet magnets for each rank of pipes.
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windchest
Advanced Member
United Kingdom
29 Posts |
Posted - 09/03/2008 : 6:33:45 PM
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Phil,
I'm sure the outputs of the JW cards are Negative !! Pull down.
I used some small relays on the 2 rank - 3 stop pipe organ thats on my website.
These work fine as can be heard if you look at the soundfile page.
Cheers chris www.smallpipeorgans.com
Chris |
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windchest
Advanced Member
United Kingdom
29 Posts |
Posted - 24/10/2008 : 5:37:09 PM
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Phil,
I need the NPN diagram for the above.
Cheers - Chris.
Chris |
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Topic |
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CURCUIT REQUIRED