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Author Topic: Powering Solenoids from Axon  (Read 1241 times)

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Offline agorilleTopic starter

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Powering Solenoids from Axon
« on: March 04, 2011, 01:45:08 PM »
Hi, I'm a total novice when it comes to electronics. I understand mechanics and programming, but otherwise I have no idea what I'm doing.

I'm working on a project which powers eight pull solenoids http://www.allelectronics.com/make-a-store/item/SOL-58/24_VDC_PULL-TYPE_SOLENOID/-/1.html from the Axon micro controller. I don't know what type of voltage regulators, MOSFETs, or transistors to use and in what type of schematic.

I'm assuming I'll need two different types of batteries, one 12v to power the solenoids (they don't need to pull back very much), and one 6v (which I already have) for the Axon.

Can someone help me decide what else I need? Any help is much appreciated.

Offline Soeren

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Re: Powering Solenoids from Axon
« Reply #1 on: March 04, 2011, 03:55:24 PM »
Hi,

I'm assuming I'll need two different types of batteries, one 12v to power the solenoids (they don't need to pull back very much), and one 6v (which I already have) for the Axon.
If it's true that they can run acceptably at 12V (and that's a big if) and if they only need a short pull with some force (and then need less force to hold them), it can actually be run from 6V with a fairly simple circuit.

@24V they need around 120mA, so a transistor like the BC337 will do nicely (or a 2N2222 if that's easier to get a hold on). Further you need 2 or 3 resistors (depending on whether the solenoids can be powered while the controller is off?) and a diode to protect the transistor.

If you decide to go with a 12V battery, you can use a voltage regulator (preferably a switch mode regulator) to drive the controller.

I can draw you a schematic on the drivers if you can read it?

Why not go with weaker solenoids (and made for 12V) if that's what you need?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Billy

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Re: Powering Solenoids from Axon
« Reply #2 on: March 04, 2011, 04:01:31 PM »
Can someone help me decide what else I need? Any help is much appreciated.

The electronics required depend on how you are going to drive it so please answer a couple questions:
Are you going to turn them on and off, or PWM the coil?
If PWM, what frequency?
Are you sure you can get by with 12V drive? They are rated 24v.
How often will you activate them and for how long?

Coils are 3.3 Ohm. Thats 'bout 3.5 amps at 12V. That's a lot of power, you'll need a low impedance power source.

Offline agorilleTopic starter

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Re: Powering Solenoids from Axon
« Reply #3 on: March 04, 2011, 04:19:50 PM »
Are you going to turn them on and off, or PWM the coil?
If PWM, what frequency?

I was thinking PWM, though I'm not sure what frequency. Turning them on and off might be easier, I don't really know.

Are you sure you can get by with 12V drive? They are rated 24v.
How often will you activate them and for how long?

I don't know if I can actually get by with the 12V. I plan on using them for about 1 ms about 30 times over the course of a minute. I'm more interested in the released spring action than the pull. I realize that these are far from high quality solenoids and that there's a high likely hood of them overheating. I just happened to have them and thought I could use them.

@24V they need around 120mA, so a transistor like the BC337 will do nicely (or a 2N2222 if that's easier to get a hold on). Further you need 2 or 3 resistors (depending on whether the solenoids can be powered while the controller is off?) and a diode to protect the transistor.
...

Why not go with weaker solenoids (and made for 12V) if that's what you need?

Would this be feasible? I'd like to use these ones because I already have them, but if you think I'd be better of getting another type I could do that.

I can draw you a schematic on the drivers if you can read it?

I'm pretty sure I'd be able to read it. Thanks!

Offline agorilleTopic starter

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Re: Powering Solenoids from Axon
« Reply #4 on: March 04, 2011, 04:31:44 PM »
If it's true that they can run acceptably at 12V (and that's a big if) and if they only need a short pull with some force (and then need less force to hold them), it can actually be run from 6V with a fairly simple circuit


This would actually probably be optimal. I'm trying to keep things as simple as possible, seeing as I don't really know what I'm doing.

Offline Soeren

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Re: Powering Solenoids from Axon
« Reply #5 on: March 04, 2011, 05:04:09 PM »
Hi,

Oh, that's what happen when you watch a movie while commenting here...
Don't know how I arrived at 120mA    :-[

It's actually 7.3A worst case (@ 24V) and a whopping 175W - Even if used for only 30x 1ms a minute, I'd find some other types (preferably 6V types) if it was me, as it will make the supply more expensive and bulkier.

1ms is probably not enough time to move the mass of that solenoid all the way!
The lighter the mass to pull the better.

What is it for and what should it drive (in terms of weight/force)?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline agorilleTopic starter

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Re: Powering Solenoids from Axon
« Reply #6 on: March 04, 2011, 06:26:06 PM »
Oh ok yeah. I guess that makes sense. I'm actually using them for a musical instrument. It's sort of like a player piano, only a xylophone instead. I only need the solenoids to move enough to create a tone out of the xylophone. (I'm an art student and this is part of a sculpture that has to make sound)

Offline Soeren

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Re: Powering Solenoids from Axon
« Reply #7 on: March 04, 2011, 07:46:59 PM »
Hi,

I'm actually using them for a musical instrument. It's sort of like a player piano, only a xylophone instead. I only need the solenoids to move enough to create a tone out of the xylophone. (I'm an art student and this is part of a sculpture that has to make sound)
Then the solenoids are way overkill. If my childhood memories ain't too faded, I'd think about 1..2 ounce of force should be more than plenty.

And 1 ms is way too short for a note to be heard (it's only one period of a 1kHz signal). I'd recommend far smaller solenoids or you could use mini servos (I've seen some of the cheapest at $2.50), which would do fine in that application - and they can be driven directly from an Axon (I or II).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline agorilleTopic starter

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Re: Powering Solenoids from Axon
« Reply #8 on: March 04, 2011, 08:46:32 PM »
Would something like this work? http://www.electromechanicsonline.com/product.asp?pid=930

Thanks for all your help

Offline Soeren

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Re: Powering Solenoids from Axon
« Reply #9 on: March 05, 2011, 12:11:07 PM »
Hi,

They are too weak. They have too little movement contra power (and they are hugely expensive - about twice that of a reasonable quality full size servo).
You could use pull type as well as push type, it's just about how you mount them.
If you measure the exact push needed, you can make a better choice.

I'd guess this solenoid is suitable and at roughly a tenth the price.

As a side note. Usually, when playing you won't press the "buttons" like a solenoid will, so mini-servos might give a more realistic sound.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline agorilleTopic starter

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Re: Powering Solenoids from Axon
« Reply #10 on: March 05, 2011, 11:17:27 PM »
Thanks so much! Because it's a sculpture, the aesthetics are as important, if not more important than the functionality, which is why I was thinking solenoids, but yeah servos would probably be better sound-wise. And I hadn't looked closely at the price of the ones I posted. WAY too expensive.

I can work on measuring the exact push needed.. my tests weren't very exact.

Thanks again!

Offline Soeren

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Re: Powering Solenoids from Axon
« Reply #11 on: March 06, 2011, 10:00:53 AM »
Hi,

Because it's a sculpture, the aesthetics are as important, if not more important than the functionality,

Sevos can be placed in a convenient place and connected via thin metal wire if needs be.

which is why I was thinking solenoids, but yeah servos would probably be better sound-wise.

Servos aren't silent either, but I think they'll be better anyway and they can be used with a much more realistic "attack profile".


And I hadn't looked closely at the price of the ones I posted. WAY too expensive.

These Turnigy TG9e servos are both small, fast and cheap at $1.99 and they have ample strength.

Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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