# output devices ## speaker ### coil, magnet, cup <iframe width="560" height="315" src="https://www.youtube.com/embed/36O36D3s9W0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> <iframe width="560" height="315" src="https://www.youtube.com/embed/2ij685XOYbg" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> ## led arrays, double sided ![](http://fab.cba.mit.edu/classes/863.18/Harvard/people/victoria/images/week_09/blue.jpg) ![](http://fab.cba.mit.edu/classes/863.18/Harvard/people/victoria/images/week_09/rivets.jpg) ![](http://fab.cba.mit.edu/classes/863.18/Harvard/people/victoria/images/week_09/traces.jpg) ![](http://fab.cba.mit.edu/classes/863.18/Harvard/people/victoria/images/week_09/components.jpg)