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Old 10-09-2011, 06:50 PM
Longhair Longhair is offline
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Default Output Question

I am working on a project similar to Mel's iPatch but with 6 relay boards instead of 4. The goal is to have "X" combinations of different switch arrangements between the 12 relays.

Is the MSA-R limited to only 8 outputs?

If so, would the MD24 MIDI Decoder work in the same way?
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  #2  
Old 10-11-2011, 09:03 PM
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John John is offline
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Hi Longhair,

Yes, the MSA has 8 outputs / unit, but you can chain two units together for 16 outputs. There is a MIDI chain wiring diagram in the MSA hardware user manual.

The MD24 does have 24 outputs, but they are not able to directly supply enough current to control most relays of the type you'd be using for signal switching. So if you go with the MD24, you'd need to add your own relay coil driver circuitry (something like a ULN2803 would work nicely).

Another thing--the MD24 does not have the same firmware functionality as the MSA, so you'd want to review the firmware user manual first, to make sure it will do what you need. If it doesn't, please add a feature request here:

http://forum.highlyliquid.com/showthread.php?t=561

Let me know if I answered your questions or not.
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Old 10-12-2011, 10:05 AM
Longhair Longhair is offline
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Hi John,

I've been working with my schematic in the simulator some more and tied everything together so it is more realistic than before. I have exactly 8 on/off points - perfect number for the MSA-R that I have floating around here somewhere.

I have a total of 17 relays now and I was wondering if I would have enough power from the MSA-R to be able to switch them all on at the same time (very worse case scenario).

Here are the specs from ebay:

Quote:
Input control signal voltage:
0V - 0.5V Low stage (relay is OFF),
0.5V 2.5V (unknown state).
2.5V - 20V High state (relay is ON).

Input control signal high state current:
2.5V: 0.1mA
3.3V: 0.18mA
5V: 0.35mA
12V: 1.1mA
20V: 1.9mA
Here is my on/off points (0-7) to number of relays connected

0 - 1 Relay
1 - 2 Relays
2 - 1 Relay
3 - 2 Relays
4 - 4 Relays
5 - 4 Relays
6 - 1 Relay
7 - 2 Relays
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Old 10-14-2011, 04:39 PM
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John John is offline
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Yes, you should be fine using the MSA-R for this. You can see the MSA-R output electrical specs in the hardware user manual.

The currents you'd like to control (~1mA) are well below the MSA-R maximum (500mA).
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