user7061: I've been teaching a blind student how to program and build electronics with Arduino. So far I've substituted LED's with piezo buzzers with excellent results. We are getting to the point where more complicated output is required and braille displays are excessively expensive. 
I've found these micro solenoids on eBay.

They are 5 volts and small enough to place on a grid to create display. Could I substitute these on a regular LED grid and run it via conventional shift register or MAX7219 methods?
Here is the link to the micro solenoids.

user14649: Yes the power requirements are a lot more than LEDs but theres a trick with solenoids which is each solenoid output would be PWM rather than DC.
You could experiment with different frequencies/duties but I reckon start with a 100-200Hz pulse at around 25-50% duty. Can drop your power down by at least a 1/4 or less. 
This is obviously a bit more complex than a simple off or on. But solenoids have no problem with holding their magnetic field with a pulse and its recommended to avoid overheating the coil.
Edit: so there are 2 ways to approach it that I see. Either dedicate 1 pin on your micro for each solenoid which would go through a driver (with diode protection) and setup a PWM routine to pulse each output. or..
use a matrix approach with an oscillator on each solenoid. Meaning you would just switch the oscillator on and off
The first approach is more code intensive and would be limited by the micro.
The second is more hardware intensive limited by the components you have.
Also to make sure they retract a short reverse polarity pulse would do that.

7061: <p>I've been teaching a blind student how to program and build electronics with Arduino. So far I've substituted LED's with piezo buzzers with excellent results. We are getting to the point where more complicated output is required and braille displays are excessively expensive. 
I've found these micro solenoids on eBay.
<a href="https://i.stack.imgur.com/wxNg7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wxNg7.jpg" alt="micro solenoids "></a></p>

<p>They are 5 volts and small enough to place on a grid to create display. Could I substitute these on a regular LED grid and run it via conventional shift register or MAX7219 methods?</p>

<p>Here is the link to the <a href="http://m.ebay.com/itm/2pcs-x-DC-5v-6V-inhaled-Type-Push-Pull-Solenoid-Electromagnet-DC-Micro-Solenoid-/331680100757?nav=SEARCH" rel="nofollow noreferrer">micro solenoids</a>.</p>
 14649: <p>Yes the power requirements are a lot more than LEDs but theres a trick with solenoids which is each solenoid output would be PWM rather than DC.</p>

<p>You could experiment with different frequencies/duties but I reckon start with a 100-200Hz pulse at around 25-50% duty. Can drop your power down by at least a 1/4 or less. </p>

<p>This is obviously a bit more complex than a simple off or on. But solenoids have no problem with holding their magnetic field with a pulse and its recommended to avoid overheating the coil.</p>

<p>Edit: so there are 2 ways to approach it that I see. Either dedicate 1 pin on your micro for each solenoid which would go through a driver (with diode protection) and setup a PWM routine to pulse each output. or..
use a matrix approach with an oscillator on each solenoid. Meaning you would just switch the oscillator on and off</p>

<p>The first approach is more code intensive and would be limited by the micro.
The second is more hardware intensive limited by the components you have.</p>

<p>Also to make sure they retract a short reverse polarity pulse would do that.</p>
