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Old 05-19-2013, 02:16 AM
Praxisaxis Praxisaxis is offline
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Default Noob questions about triggering solenoids

Hi,
I’m beginning a project where, essentially, three or four solenoids are triggered by MIDI, using one of the Highly Liquid interfaces. I am new to most aspects of setting this up.

I’m aware that many other people have made the same device.

I have a bunch of questions I hope you can help with (I’m sure these are “standard”).

* What sort of power should the solenoids be? I’m hoping to use them to actuate small wooden or metal levers to strike small hand-made percussion instruments. Would a 12 volt solenoid do the trick? I’ve mucked around with 12 volt solenoids, and they seem to have plenty of torque… but am I right?

* Please tell me if I’m thinking about this correctly:

1) The solenoid is powered by its own power supply (e.g. 12 volt DC), and its voltage is switched on and off by a transistor which is triggered by the 5 volts supplied by the Highly Liquid device).

2) I understand that because of their inductance, solenoids will push current back when switched off, and this can be problematic. Therefore, you need a diode to go in parallel with the solenoid, to dissipate the current when the solenoid goes off.

* Are there any other components needed in the above arrangement?

* I still can’t “mentally picture” the circuit. Are there any schematics for what I’m thinking of doing?

* How do I establish a) what transistor I am to use, and b) what diode I am to use?

* Are there any other issues I should be aware of in order to achieve what I’m aiming for?

* Noob question: What are “terminal blocks” in the MSA-T kit? I’m happy to solder one up myself (have done soldering before), but I don’t know what the terminal blocks are for.

Thanks in advance,

-
Tom
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  #2  
Old 05-19-2013, 10:44 PM
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John John is offline
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Hi Tom, welcome to the forum.

Quote:
Originally Posted by Praxisaxis View Post
Hi,
I’m beginning a project where, essentially, three or four solenoids are triggered by MIDI, using one of the Highly Liquid interfaces. I am new to most aspects of setting this up.

I’m aware that many other people have made the same device.

I have a bunch of questions I hope you can help with (I’m sure these are “standard”).

* What sort of power should the solenoids be? I’m hoping to use them to actuate small wooden or metal levers to strike small hand-made percussion instruments. Would a 12 volt solenoid do the trick? I’ve mucked around with 12 volt solenoids, and they seem to have plenty of torque… but am I right?
The voltage rating for the solenoid won't tell you too much about the force of the push/pull. You'll have to check the datasheet for the force rating. It's very likely that you will be able to find a 12V solenoid that works well for your application.

Quote:
* Please tell me if I’m thinking about this correctly:

1) The solenoid is powered by its own power supply (e.g. 12 volt DC), and its voltage is switched on and off by a transistor which is triggered by the 5 volts supplied by the Highly Liquid device).
Yes. If you have an MD24, for example, you can wire as shown in this example:

http://forum.highlyliquid.com/showthread.php?t=3

(The diagram shows a 9VDC power supply and 9VDC solenoid, but it would work equally well with a 12VDC power supply and 12VDC solenoid.)

The MSA-T has the transistors built-in, so you can wire the solenoid directly to the MSA-T. For example:

http://forum.highlyliquid.com/showthread.php?t=985

(The diagram shows relay coils being driven by the MSA-T, but the same arrangement works for solenoids.)

Be sure to review the MSA-T hardware manual and compare the output current limits to the current draw of your solenoid.

Quote:
2) I understand that because of their inductance, solenoids will push current back when switched off, and this can be problematic. Therefore, you need a diode to go in parallel with the solenoid, to dissipate the current when the solenoid goes off.
Yes. Something like 1N4004 will work fine for that purpose.

Quote:
* Are there any other components needed in the above arrangement?
Not really. You may find additional forum threads that have some project photos that will help make it a little more "real". But ultimately it will not be too complicated to set up.

Quote:
* I still can’t “mentally picture” the circuit. Are there any schematics for what I’m thinking of doing?
Let me know if you have questions about the schematics in the threads linked above.

Quote:
* How do I establish a) what transistor I am to use, and b) what diode I am to use?
The MSA-T uses the TIP122. This is commonly available. Again, check the current rating of your solenoid and compare it to the current rating for whatever transistor you decide to use.

Quote:
* Are there any other issues I should be aware of in order to achieve what I’m aiming for?
Check out these pages for some excellent background info for your exact application. All the issues you have mentioned are addressed on these pages:

http://electronicsclub.info/transistorcircuits.htm

http://electronicsclub.info/transistors.htm

Quote:
* Noob question: What are “terminal blocks” in the MSA-T kit? I’m happy to solder one up myself (have done soldering before), but I don’t know what the terminal blocks are for.
Terminal blocks allow you to connect your wires to the board without having to solder. Instead, you insert the wire end and tighten with a screwdriver. This is useful if you need to make changes to your wiring.

I hope this helps. Please let me know if I can provide more information.
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  #3  
Old 05-20-2013, 01:46 AM
Praxisaxis Praxisaxis is offline
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Wow, thanks John. That answers all my questions 100% . This now appears to be a relatively straight-forward project! Thank you so much for your help.


One additional question:

The kits like the MD24 receive MIDI information which requires no special coding: i.e. If I were to plug in a MIDI keyboard, with its channel set to 1, I could fire off signals by playing a key; or alternatively I could send signals from, say, a piano roll in a DAW, with its channels/patching set appropriately.

Am I understanding this correctly?

Thank you again, much appreciated.
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  #4  
Old 05-20-2013, 02:28 AM
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John John is offline
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Quote:
Originally Posted by Praxisaxis View Post
The kits like the MD24 receive MIDI information which requires no special coding: i.e. If I were to plug in a MIDI keyboard, with its channel set to 1, I could fire off signals by playing a key; or alternatively I could send signals from, say, a piano roll in a DAW, with its channels/patching set appropriately.

Am I understanding this correctly?
Yes. All of the products respond to standard MIDI notes.
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