Unusual project, need an unusual solenoid

[bradleybj09]

Hi everyone,
I'm building my own stop action magnets for a pipe organ.
The actual action is effectively just a rod that will activate a reed switch when in the 'drawn' position, and deactivate in the 'pushed' position. I have that all under control.

The difficult part is that the whole array of knobs can be activated electronically instead of manually. The usual way this is accomplished is by having a push-pull double solenoid. Basically, just two solenoids on the same armature. I've seen a thousand push/pull solenoids that are spring activated, and latching solenoids that use a permanent magnet (and spring), but I honestly just need a double-magnet solenoid. I saw a picture of one, once, but I can't find it again and couldn't find it attached to a product anywhere. Does anybody know of such a thing? My other options is just building my own solenoids from scratch, but that's been troublesome just to find the right parts, organize, etc.
Thanks!

Edit - these are bistable solenoids, but I have a lot of trouble finding what I actually need. I get a lot of latching solenoids when I look for bistable.
Second edit - I'd love a half-inch to inch stroke. I don't really know how to quantify the force needed, but enough to move a wooden rod in a felted hole. Rod size is unimportant.

 

[KeepItSimpleStupid]

With that kind of stroke. I;d be thinking lubercated air. A double acting air cylinder. There is a 4-way valve to activate. Some have the ability to adjust the rates. You might also have to filter the oil laden discharge air.

 

[Visitor]

How about a car lock actuator solenoid? A pulse with one polarity pushes it out. A pulse with reversed polarity pulls it in. Travel is about an inch.

 

[rjenkinsgb]

How about RC servos? they are cheap and absolutely controllable with a small microcontroller.
(Or you can control each one with a 555 timer and a pot or relay contacts).

Use an arm on the servo that sits in a slot/notch or between two pegs, so in the neutral position the stop can move end to end before the servo arm gets to the end of the slot.

By briefly running the servo to one side or the other, it could push the stop in or out.

You can get small ones for under a pound each - eg.
**broken link removed**

 

[alec_t]

I'm no organist, but it seems rather tortuous to have electronically-operated solenoids which move rods and magnets to operate reed switches. Couldn't you simply use electronically-operated switches (transistors) across the reed switch contacts?

 

[dr pepper]

They make rotary solenoids that might be able to do the job, they tend to be pricey, although you might find some surplus.

 

[bradleybj09]

alec_t the primary function of the drawknobs is to be pushed or pulled by hand. The solenoid simply mimics that action. It could all happen simply inside the computer, and the primary use of this software is to connect to a touchscreen. But, that looks bad, this'll be in my living room, and I want it to be a functional instrument as well as a architectural/design piece.

dr pepper are the rotary solenoids able to do linear actuation? I still want to be faithful to the design of an organ and have actual pull/push drawknobs.

rjenkinsgb I'll check that out, I know little about servos.

Visitor honestly, I can't believe I didn't run across an actual product for a car lock solenoid the whole time I've been looking. I know that solenoids are in use in car locks, but one commercially for sale never showed up. I'm unfortunately limited by the board I need to interface with (12V, solenoid-in, solenoid-out, and state), so I'd have to to some circuitry work to get this to place nice with that. Also, I'd have to disassemble it and use parts, because I need access to both ends of the armature.

 

[Visitor]

I came across one of the lock solenoids at a thrift store and bought it for a buck or two. I was kind of surprised how well it worked and amazed to see them for around five bucks on ebay. The reverse-polarity operating scheme is a bit different but the zero-current-draw to maintain position has some interesting possibilities.

 

[Pommie]

You might want to look at model railway point motors.

Mike.

 

[KeepItSimpleStupid]

It's basically a motor driven rack and pinion. It really doesn't maintain position.

 

[Pommie]

It's basically a motor driven rack and pinion. It really doesn't maintain position.

What is?

Mike.

 

[Mickster]

What is?

Mike.

The universal door lock/unlock solenoid, sorry, actuator.
EDIT: correction.

 

[KeepItSimpleStupid]

The reverse-polarity operating scheme is a bit different but the zero-current-draw to maintain position has some interesting possibilities.

I took that line.

and added my line.

It's basically a motor driven rack and pinion. It really doesn't maintain position.

You were "supposed" to be smart enough to infer the connection, sorry. I have a splitting migraine so I probably should; not be posting.
"It" should have been referred to by name.

if you pull on the end of the actuator, it will move. It sure beets a beefy solenoid that I used for power door locks.

Mickster nailed it.

 

[KeepItSimpleStupid]

Comments:

RC Servos have a rest position and must be continually pulsed. It's usually configured to be +- some degrees.

Rotary solenoids are really strong. I've used two types.

1. For continuous operation, you have to reduce the power after activaton. I used a passive circuit. This was a shutter to a fiber light and plenty of cooling was available in the housing,

2. The other was a dual thingy and more like a rotary motor with two coils for each direction. It wasn't my design.

In a plain solenoid application, I had to "slow" the activation because it was a shutter next to a 1mm thick optic filter that cost about $800 .00 USD. I used a ready made PWM controller for motors with "slow start".

There are solenoid or injector driver IC's that pulse and reduce the power.

For the auto door lock, you have to move it and probably go in constant current mode and continue with the force you need tomaintian position.

 

[Visitor]

....For the auto door lock, you have to move it and probably go in constant current mode and continue with the force you need tomaintian position....

Guess you've never seen how stops on an organ work. They are easily-moved sliders (finger tip pressure) that move in or out roughly an inch. When you push them to the desired position with a finger, they stay put. The slight friction of the mechanism holds them in place. So in this case, with the electric door lock mechanism, there is no need for anything beyond a pulse to move it in or out.

 

[Pommie]

This is what a point motor looks like,

Kinda fits the opening description exactly. Not sure if the stroke is big enough but larger scales are available. And only $5.

Mike.

 

[dr pepper]

Apologies, I was under the impression you were controling the plungers on the pipes, not the draw knobs.

 

[alec_t]

Be aware that car door lock actuators come in various flavours. Some are the rack-and-pinion type and others are the worm-drive type.
Since you need to be able to manually over-ride the draw-bar actuator, avoid worm-drive mechanisms.

 

[Musicmanager]

You don't say where in the world you are but the usual supplier of drawstop solenoids in the UK is Kimber-Allen UK ltd in Swanley, Kent, the price of the things however, may be another matter.

In the early days of conversion from pneumatic to electro-pneumatic and then entirely electronic a variety of applications were tried, some reasonably successful, some not so. You might find **broken link removed** of some interest.

Have a look at this .. .. .. .

That is a typical pneumatic action for a drawstop, very dated and time limited. For many years it was common to see everything from poppet down removed and replaced with a single solenoid on one side and a pair of counteracting springs on the other; the outer tip of the pivot was in touch with a microswitch.

Another thought is that many churches are removing pipe organs because of the expensive upkeep; they often appear on Ebay - you may be lucky and find an abundance of the K-A solenoids going for peanuts.

S

 

[bradleybj09]

Pommie - that motor looks interesting, I'll check it out.
Musicmanager - yep, K-A, Syndene (I'm in the US and they're the modern standard for us), Peterson, and more. I just don't want to spend $50 a pop for a hundred units. I've seen a few full consoles on ebay, but never in the volume that I'm looking for. This is a totally ground up Hauptwerk project.

My partner is a proper electrical engineer unlike me, and while exploring purchasable options, we've also been experimenting making our own from scratch. We've got a 3d printer and some willpower, and a lot of magnet wire and different things to experiment for armatures / tubes. This is getting more promising, but I am going to look more into a couple of the options here.

Thanks for your help everyone