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Adding midi to an organ pedalboard

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Ok. I have all of my parts (I think). Now I need to start putting the electronics together and I could use some advice as to where to start. Is there a "How to solder" website that you would recommend? I've seem a lot of them from a google search, but who knows if they're any good. Then I need to know which part connects to here and which part connects there.

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Is there a "How to solder" website that you would recommend?

There are a fow excellent soldering tutorials linked from these forums... use the Search :)

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Have a look under "Basics" in the DokuWIKI.

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Just a comment about the switches. I have built lots of Bass pedals, and the reed switches are a nightmare. Ok, they last a long time but they are fiddly and hard to mount to stay in place, the movement is only small (about 3mm) when you press a pedal.

I would recommend microswitches, they mount easily, already have a lever for activating, and last a long time and are sealed.

To be honest though, the old old organ boards had a spring wire on the pedal, and a wire bus bar across all the pedals to be contacted with the spring wire, very crude, but they all still work fine after many many years.

You can spend a lot, only to find it overkill.

good luck though

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I'm glad you mentioned that. I am indeed having difficulty with the reed switches. The magnets I got don't close the circuits unless they touch the switch. I have a few stronger magnets, but they don't close the circuits consistently. Can you tell me which model of microswitches you recommend?

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I use ones like this;

Ebay item number 150230053053 (just put the number in the search). You can also get them with small rollers at the end of the lever.

They're easy to mount. My method is two lengths of 1/8" threaded rod long enough to span all the pedals, a handful of same size nuts and some small corner 'L' brackets. The switches slide along the rods and you can place them anywhere with locking nuts. L brackets slide along the rods and lock with nuts also, to hold the assembly to the base at enough places to keep it all rigid. If you use longer machine screws or bolts to mount the 'L' brackets to the base, you can use locking nuts to hold the bolts to base, then lock the whole assembly on bolts at just the right height. All from any hardware store for $3-4.

hope this gives you some ideas.

Keith

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I forgot to mention, using threaded rods means you can also use one or both as a bus bar if you insulate it from any metal base.

Keith

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Well I can't get to my pedals right now, they're in transit. But here's a couple of diagrams that may help you.

good luck

Keith

switches1.jpg

switches2.jpg

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Ok, I went to a local electronics store and bought a microswitch to test out. It's has the roller on the lever. It seems much more consistent than the magnetic reed switches. I bought a more powerful magnet while I was there too. The magnet is more useful than the other ones I was using, but I still like the microswitch better.

Is the clicking noticeable when you're playing?

I can't tell from your diagram, are you mounting them above or below the pedal? Are you bending the treaded rod assembly to follow the curve of the pedalboard?

Last question, at what point in the pedal's travel should it trigger the switch? The one switch I tried is pretty...micro. It engages about 2/3 or 3/4 of the way down at best. The same store sold some bigger ones I might try.

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The clicking is not really noticable if you play loud. Ok, that's not helpful. Some micro switches are quieter than others, but I've never heard of anyone being bothered by it.

I usually mount the micro switches above or at the rear of the pedals, (normally there's not enough room underneath) and bend the switch levers so that they can be screwed or bolted to the pedal, and mount the switches on a frame made of threaded rods and 'L' brackets.

You have to experiment to find the best place on the pedal to attach the switch, closer to the pivot with produce a small travel, further away, a larger travel.

Another alternative is to attach a small 'Z' shaped bracket to every pedal so that depressing the pedal will 'pull down' on the lever. This is better on some pedals designs.

I think you said you had a 32 note pedal board. They are many different construction methods, maybe yours are pivoted under the bench, so you might be able to mount the micro switches under or at the other end of the pedals, but often the return springs get in the way. I have done it with just an 'L' bracket for each micro switch, but it really depends on how your pedals are designed.

Yes I would bend the threaded rod frame to follow the curve of the board, it's important to have every pedal 'feel' the same.

Ideally, the whole micro switch frame should be able to raise or lower, therefore giving an overall adjustment for the trigger point of the switches. It's a personal thing, as to how far down the pedal should move before it operates the switch, I know there's some debate about it. The best solution is have adjustability, experienced players can move swiftly and lightly, novices seem to want to stomp.

If you describe the pedals  in more detail, a 'best way' will be easier to find.

Keith

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If you describe the pedals  in more detail, a 'best way' will be easier to find.

The pedalboard is concave and radiating. The "toe end" of the pedals have L brackets on the end of each pedal where the bend of each L is at the same level compared to the floor. The "travel" of each pedal is around 7/8ths to 1 inch. The "travel" of the microswitches is approximately 1/2 inch with actuation at around 1/4 inch.

Ideally, I would mount them above or below (they can be wired normally open or normally closed) the level portion of the L brackets so they could all be at the same height. The down side is I would only be able to actuate the switches by pressing the pedal 1/4 or less, or 3/4 of the way down or more due to the limited travel of the microswitch. I'm not sure I want dismiss using the middle range of the pedal travel. To use the middle range I could mount the switches on the underside of the pedals part way between the "heel" and "toe" but each switch would need to be at a different level, or adjustments brackets or blocks would need to be added to each pedal to provide consistency. Alternatively to take advantage of the L brackets that are already there, I could mount the switches on an angle and attach angles (probably cut some right triangles from a 2x4) to the L brackets. That would amplify the travel of the microswitch - larger angles would result in  more pronounced exaggeration of the microswitch. The switches have rollers on them, so they shouldn't have trouble either way.

I went to Home Depot yesterday to look for some treaded rod and came home empty-handed. The holes in the switches are only around 3mm and I couldn't find a rod with a small enough diameter to fit. My back-up plan is to use L brackets or cut some wooden blocks to hold the switches then attach those to a piece of wood or metal. I'm leaning towards wooden blocks because I can make them all different heights and mount the switches underneath the pedals halfway between "heal" and "toe" to allow me to adjust the actuation point anywhere along the full travel of the pedal.

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Re: the threaded rods. If you look for 3mm machine screws that are long enough to mount just 8 switches on (you should find them in a good hardware store), and enough nuts, you will have 4 banks of eight switches, which is the same configuration as the DIN module. You will be able to use one of the machine bolt as a common bar for each group of 8 switches, and make it much clearer to see where you are when wiring them up. Also you might not have to bend the machine screws.

The "toe end" of the pedals have L brackets on the end of each pedal where the bend of each L is at the same level compared to the floor.

I'm not sure what this means, can you try again? Are the L brackets the old contacts or pushers? If they are, why change them for new switches?

An alternative idea;

If the problem is the amount of travel of the pedal being more than the switch, maybe you can mount a switch on the side of each of the pedals, at the toe end, instead. Then you only need something adjustable for them to push down on. Maybe you can re-use the L brackets for this, perhaps fixed to the frame at the toe end.

(they can be wired normally open or normally closed)

Normally open is what you will need for the DIN module.

Keith

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Paul,

Progress is slow because I have little spare time. Almost done with adding switches. Then I've got to put the midibox together.

Anybody know if I can use just the one module and to change channels on the midi IN?: when complete, I'll have two keyboards and a pedalboard. I'll need each of these on a separate midi channel (the actual channel is arbitrary, so long as they are different from each other). My keyboards both default to channel 1 at power on, and I'd rather not have to change them manually every time I sit down. Can I connect the Out of one keyboard to the In of the midibox (pedalboard) and have the midibox change that signal to channel 2, and have it transmit the pedals themselves on channel 3? Then I would plug the pedals into the other keyboard. That keyboard would connect to the computer sending channel 1 for itself, 3 for the pedals, and 2 for the other keyboard. Is that realistic?

I think I remember someone asking how heavy the pedalboard is. I weighed it on my bathroom scale as 82 pounds.

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Question,

I would like to have the LCD visible away from the pedals (near the manuals) so I can see it while playing. I was thinking there are two ways to do this: either have the midi box up there and a long cable (33 to 40 pin) that connects to the switches below, or have the midi box below with the pedals and have a smaller-pin cable going up to connect to the LCD (and possibly midi too).

So here's the real question is what's the best way to do this? I was think about having the midibox up top, but I couldn't find a convenient cable that would handle all of the switches (I'd like to do it with only one cable). So then I thought about enclosing the midibox in the pedal assembly and connecting the wires for the LCD (16), power (2), and midi (5) to a 25-pin cable, like this http://www.directron.com/ieeedb25mm6ft.html. Then in the manual assembly, I would direct the individual wires to their appropriate destination. Would there be any issues with having 6 feet of wires separating the LCD and the midibox? What about having LCD, midi, and power all together in such close quarters for 6 ft?

Alternatively, anyone know of an affordable cable (with corresponding affordable sockets) with enough pins so I could put the midi box up near the manuals? I'd prefer something durable like a parallel printer cable instead of a ribbon cable. What's the minimum number of pins I would need? 33? One for each pedal, and one common ground? The closest thing I could find online was this: http://www.cyberresearch.com/store/data-acquisition-control/pc-computer-cables/CBL_3706M_1751.5.htm, but it's expensive, and I can't find any sockets for sale anywhere.

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I would like to have the LCD visible away from the pedals (near the manuals) so I can see it while playing. I was thinking there are two ways to do this: either have the midi box up there and a long cable (33 to 40 pin) that connects to the switches below, or have the midi box below with the pedals and have a smaller-pin cable going up to connect to the LCD (and possibly midi too).

So here's the real question is what's the best way to do this?

I would put the DIN in with the pedals and connect it to the Core up top with a 5 wire cable. A 6 wire mini-DIN cable used for keyboards and mice is inexpensive.

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To be honest though, the old old organ boards had a spring wire on the pedal, and a wire bus bar across all the pedals to be contacted with the spring wire, very crude, but they all still work fine after many many years.

I was thinking of the same, but many DIY boards recommend using a reed switch, is there any particular reason for that ?.

I find magnetic reed switches are problematic, especially midifying old manuals, can't we use a simple 2 wire contact ?.

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I'm wondering if anyone has tried/considered using photointerruptors?  They do need a power supply. I think the transistor side would be fine with MIDIBox.  The pedal would only need a vane on it to interrupt the beam so you get complete non-contact switching and also adjustment by moving the vane rather than the electronics.

Here is a basic how-to.  In the circuit on this page, the 1k resistor is already present on the DIN board. 

http://www.makingthings.com/teleo/teleo/cookbook/ir_interruptor.htm

Cheers

Graham.

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I find magnetic reed switches are problematic, especially midifying old manuals, can't we use a simple 2 wire contact ?.

Of course you can use a simple contact. Piano wire is good for making your own spring wire. Really the problem is figuring a way to mount whatever you are going to use, micro switches or simple contact wire. You don't want the connecting wires to connect to moving parts i.e. the pedals themselves, as the constant movement will quickly break the wire.

bassman

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A real pipe organ usually draws about 100 mA through a key (or pedal) contact to an inductive load, a solenoid coil. When the contact opens it sparks and that burns off dust and dirt that might settle on the contact. Contacts that switch substantial loads are sometimes termed "wet" contacts. When you are switch for a Midibox DIN, the input draws negligible current without sparking. These are termed dry contacts. It is more difficult to provide reliable dry contacts than wet. If you look at relays, you'll find that there are relays specially made for use in dry contact situations. (Just so I don't mislead anyone, relays don't like inductive loads because the contacts are usually fairly close when open which allows the inductive sparks to do more harm than good.) So you might find that you have to clean spring wire contacts on a regular basis when used as dry contacts. I've never tried it but Stabliant 22 (http://www.micro-tools.com/store/item_detail.aspx?ItemCode=22 might be helpful.

To avoid the moving wire problem, the wire contacts (silver plated phosphor bronze is preferred) are provided on blocks having two or more spring contact wires. One is connected to the common bus the other(s) are connected as signal wires. A shorting bar, a strip of brass with a silver coated edge, is connected to the moving pedal to short together the spring contact wires.

Magnets and reed switches are attractive for pedals because they are less expensive and more reliable than the spring wire contacts IF you can get the magnets aligned correctly with the reed switches. You have to experiment with this because the alignment is not a simple one based on aligning the parts. You have to put the magnet where the magnetic field will interact properly with the reed switch. Reed switches are not good for manuals because the keys are too close together.

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I'm wondering if anyone has tried/considered using photointerruptors? 

I believe the keyboards in Allen Organs use some form of photointerruptor.  I've got a picture on the other PC, I'll see if I can find it.  Ah, here it is:

allen_optical_keying.jpg

My pedalboard uses a different method, the ends of the pedals are painted black and there is a strip of reflective tape near the top.  When the pedal is depressed the tape moves in front of an emitter / detector pair and the pedal movement is sensed.  Works well unless the tape falls off (damhik).

                                                                                                  ---john.

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