Thread: Accessory port
View Single Post
Old 07-29-2012, 11:24 AM   #4
geekmaster
Carpe diem, c'est la vie.
geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.geekmaster ought to be getting tired of karma fortunes by now.
 
geekmaster's Avatar
 
Posts: 6,433
Karma: 10773668
Join Date: Nov 2011
Location: Multiverse 6627A
Device: K1 to PW3
Quote:
Originally Posted by mmatej View Post
Thanks for the karma! I think it could not be used as input port (also, I am not going to try it - there is currently no easy HW "unbrick"). While I was playing with the port, I've also tried to connect it to the piezo speaker and no way it could power speaker directly (even a piezo). I almost couldn't hear it (and with increasing freq -> decreasing volume).

Maybe next time.
Piezo earphones can be heard quite loudly driven by a germanium diode (1N34A or quivalent, as used in old "crystal set radios"). Perhaps your piezo speaker element wants 5 volts?

I would think that anything that can power an LED could surely drive earphones.

Also, piezo "speakers" are very frequency sensitive, with a small range of resonant frequencies. They work great as "beepers", but are very poor for general sound output. I would use cheap (dollar store) headphones or earbuds for testing...

EDIT: You were probably driving the piezo speaker at a frequency too low for it. They are not good at delivering low frequencies from such a small surface area (unless you use many of them in a phased array). They are GREAT at ultrasonic frequencies though.

Last edited by geekmaster; 07-29-2012 at 11:37 AM.
geekmaster is offline   Reply With Quote