Phatline

e-organ, Key-switches to Ground > but Dout Gives +5V how to reverse?

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I am trying to midifcate my electronic organ.

The Organ itself gives the loudest sound when feeding it with Keypresses on "Groundlevel".

But a HC595 gives me +5V. - How to manage that.

 

Any idea?

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Inversion in software?

0 -> 1

1 -> 0

Done!

 

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na...  i have tried that already...

i inverted my code ----- but then all Voices where sounding a bit (@but all Voices get 5V > means "please no sound"), also the Voice Chip was getting warmer....

i thenplayed arround out with a 4MOhm Poti a resistance in series with a DOUT-pin, and find that a 1Mohm Resistor kills the sounding, but when i then activate a voice (means deactavate a DOUT-Pin >  Midibox = 0V) the Played Volume/Gain is a about 1/4 of the loudness  - when i connect it to ground directly...

 

maybe i need some circuit around the HC595?

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Phatline,

Can you  elaborate on your electronic organ; type, electronic encoders, etc.  when you say "midificate"  thats not quite enough for objective understanding. some interpretations could be:

1.  you strip out all existing internal electronics and install key switch encoders DINs, a midibox core device  (core 8, Lpc17, etc.) runnning midio128 or other. using a pc for relay operations.

2.  You only want to  force the existing organ to play by, in effect, forcing keys down electrically rather then by finger.

I assume "kepresses on ground level" means the contact actuated by the keypress is grounded on one side such that the input to the key encoder goes to ground.

How are you attempting to midify the existing system?  Are you trying to parallel the two systems by signal input from the key switch contacts, or, are you trying to force the voltage on the key switch input to the existing system.

As I read your words, it sounds like you are attempting the later, applying a short across the key switch contact by having the output pin of the 595 go from 5vdc to 0.  I would think that the suggestion to invert the action of the dout  ( reverse the output voltage swing from  high output when on, to low output when on).

As a alternate you could add ULN2003's or ULN2803s  (/quad. drivers) for all outputs on the douts, and parallel the output contact of the uln with the keyswitch contact.  With 0vdc at the output pin of the 595, the voltage of the output on the uln would be supply (cold be 5vdc) with 5vdc out of the 595, the ULN output would go to zero.  This could work provided it doesn't screw up the existing key switch encoders.

You could also drive small relays with the 595 with a relay contact shorting the keypress contacts.

Again, what are you trying to do overall?

sorry I can't be more helpful!

Johnc

 

 

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first thankz for replay...

 

1. Make the Organ a midi-soundmodule - means: play sounds via Midi

* i dont want to remote the Soundregisters - i will do that orginal on the device

* that means i Remove all "Gate"-Cables and rewire it via Digital-out-shift-registers

* integrate my trigger-melody software, and a midilooper

for 1 - no problem, except the Ground thing > 0V of the Shiftregister is not Ground enough...may it be the impedance i dont know. ;) i played around with potentiometers, and i got a impedance that worked, but with that the "high"-state is not high enough ... maybe the ULM will do the job!

 

2. Recable the orginal Keyboard with 3xDINX4Modules....

how ever in the meantime i got a "CRUMAR 198 Sustain" and this device needs +15V @ Gate Input.... a BC549 do the job for organ sounds...a extra10uF and 1K resistors gates the Fade-out sounds (Piano sounds)

the crumar sounds better and it costs me nothing except petrol...

 

but its good that you write about the ULM.

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I am trying to midifcate my electronic organ.

The Organ itself gives the loudest sound when feeding it with Keypresses on "Groundlevel".

But a HC595 gives me +5V. - How to manage that.

 

Any idea?

Do you try transistor switching yet? with npn ?

As John say you can use darlington array !

Zam

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That's what I was thinking, it will totally depend on your actual organ as to what solution would work, but the ULN driver chip is an easy hardware fix for inverted gates. As a bonus, you can supply the chip with a higher voltage and it will act as a level shifter if you need say 15 V for S-trig.

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a uln2803 for S-Trig... yes that makes the job

large.S-Trig-Module-2.JPG.355222bb1dbc2a

 

 

any idea for a transistor array for a V-Trig 15V? for my other organ?

@the moment i use BC337...by the way the Caps  make the Piano-Trggers, while the standart output of the BC337 make the Hold-Organ-Trigger

large.55d501d1ddfac_Gates-BC33715V.JPG.f

Edited by Phatline

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any idea for a transistor array for a V-Trig 15V? for my other organ?

ULN2803 :)

check the datasheet

Zam

 

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checked the datasheet... i tryed 1K Resistors to 15V on the output but with that i got in "low Mode" 1,5V.... high 15V.... but i need 0V @low?

a little bit info pleas- thankz

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There are quite a few ways to level shift for gates. It can be done very simply with transistors or the ULN chip as suggested, but you might have to invert the gates in software. It seems a little strange that the low side doesn't swing to 0V, but I'm not too familiar with the chip.

7407 is a hex buffer with open collector outputs, so you can pull up to any voltage you need with the appropriate protection resistor. If you search, I have a PCB design on this forum.

I know Altitude and the MIDIALF use CD4504s. I still haven't tested my newer circuit with 4427 dual MOSFET drivers but that should be okay too. More ideas here:

https://www.muffwiggler.com/forum/viewtopic.php?t=135374

 

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checked the datasheet... i tryed 1K Resistors to 15V on the output but with that i got in "low Mode" 1,5V.... high 15V.... but i need 0V @low?

a little bit info pleas- thankz

mmm!

Do you share the same 0v (ground) ref at both side ? or is you output floating ?

Aslo 1.5V sound like two diode voltage drop, like a darlington... should be a coincidence...

Zam

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yes it shares the same ground

anyway i realized via BC549 Transistors.

DOUT-PIN>10K>Base

+15V>1K>Collector

Ground>Emitter

the whole thing x44 = 500mA... seems the 1K is a bit low ;).... 500mA is not much but.... enough to screw my Powersupply with dry elkos.....

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Do you try with lower base limiting resistor value ? Look little hi to me but I don't do the math...

And as you say load maybe too low?

As a start try to swap the two value

Zam

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