Linear motion solenoid to push a switch

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electroRF

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Hi,

I'd like to have a linear-motion solenoid to push the PC of a switch for ~6 seconds to switch it off, and then additional shorter press to turn it on, as sometimes the PC gets stuck.

The solenoid will be controlled via a micro-processor's digital I/O pin.

Would it be possible to find a 5V solenoid which its current could be provided by the digital I/O pin of the micro-processor?

Could you please recommend on such 5V solenoid to turn off/on a PC via its Power Switch?
 
food for though, why use something mechanical, when you could use an electronic switch to "switch" something electrical??
 
electroRF said:
The solenoid will be controlled via a micro-processor's digital I/O pin.

Would it be possible to find a 5V solenoid which its current could be provided by the digital I/O pin of the micro-processor?
Click to expand...
There is too little power in a digital I/O pin. You need at least a one transistor amplifier.
Look at 'servo motors' for RC and robots. Most work from 6V batteries and may work at 5V. The control line can be driven from a I/O pin. Most are 1/4 or 1/2 of a circle. Some are linear.
 
A read relay could be connected in parallel with the existing switch and should be able to be driven by an output. Note that if this is a pic then two outputs can be paralleled to provide 50mA sink current.

Mike.
 
you mean connect the relay to switch off / on the mains' power that feeds the PC?

this is not recommended, it could harm the PC.

I wanna use the Power button and simulate a human finger.
 
electroRF said:
you mean connect the relay to switch off / on the mains' power that feeds the PC?

this is not recommended, it could harm the PC.

I wanna use the Power button and simulate a human finger.
Click to expand...
No, connect the relay in parallel with the power button.

Mike.
 
but I don't want to disassemble the PC's button.

I wanna be able to put it in front of the PC's button, just like a human finger.
 
electroRF said:
but I don't want to disassemble the PC's button.

I wanna be able to put it in front of the PC's button, just like a human finger.
Click to expand...

You don't have to disassemble anything. This question comes up every now and then and the best way to simulate remotely pressing and holding the power button is to place a set of contacts in parallel with the front panel button. Actually a very small inexpensive relay would work just fine. The computer case has a collection of wires that go from the front panel to the motherboard. The motherboard header has pins that mate with the front panel connector(s). The button is normally labeled PWR. All you need to do is at some point tap into the two wires hat run to the power button.

Believe me this will be much simpler and more effective than trying to do this with a solenoid. Just make sure that your PC is OK with a hard shutdown as that is what I believe you get when the power button is held in to force a shutdown.

Ron
 
hi Ron,
I got you.

You see, in order to "tap" into the two wires that run to the power button, i need to disassemble the case of the PC.

Then, I need to either expose these wires and solder mine in parallel, or just solder it to some exposed pins.

Then, I'll need to somehow close the case and keep the relay soldered to the wires.

That is what I'd like to avoid.
 

Yes, I agree. However, using a solenoid while it sounds simple really isn't that simple to do. This type solenoid may be a good start. The only problems are mounting it to the case and it will protrude from the case. Next is driving it from a micro controller might require using a transistor depending on the coil current needed. There are plenty of solenoids out there used in robotics and such, you don't need much force. With a 5 volt coil it can get touchy as to needed current. Me? I would just open the case and take the other route but if a solenoid is what you want then look for units like I linked to. Hopefully mounting won't be difficult. I don't know any good sources in Portugal.


Would it be possible to find a 5V solenoid which its current could be provided by the digital I/O pin of the micro-processor?
Click to expand...

Micro controllers just don't source much current, try a few robotics sites for finding a solenoid that runs off 5 volts beyond what I linked to. You might be able to hack one out of an old CD or DVD drive but not sure if those are 5V or 12V and I think 12V.

Ron
 
Hi Ron,
Thank you very much.

As for the Solenoid - I actually saw earlier the one you linked to.
It has 4.5mm throw - does it mean that its arm could reach 4.5mm from its initial location?
If so, you think that 4.5mm are enough for PC button?

As for the Solenoid driver, I don't think it'd be a problem - all it takes is connect a GPIO to a BJT's base, and the BJT will switch on/off the solenoid.
 
Yes, the throw on a linear solenoid is the amount of travel the shaft has. My guess is that depending on the PC that 4.5mm should be enough. When designing the mount just a matter of allowing some pressure already applied to the switch. like a little pre-load.

Ron
 
Instead of a solenoid you could use an RC servo. Probably similar price, and more controllable than a solenoid (which would thump the switch hard).
 
How about wake on LAN much easier and nicer, RJ45 from a pic with Ethernet, no need to cut wires or try and mount solenoids.
 
alec_t said:
Instead of a solenoid you could use an RC servo. Probably similar price, and more controllable than a solenoid (which would thump the switch hard).
Click to expand...

Hi Alec

How would you design the HW of the RC Servo Motor to be able to simulate a "finger" to press a button?
 
Standard RC servos come with an output arm which rotates through at least 90 degrees. The arm end could push the button.
 
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