Quote:
Originally Posted by geekmaster
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. |
I were not driving it at wrong frequency. No matter if I do
Code:
while true; do echo 0 > ${ac}; usleep 100; echo 1 > ${ac}; usleep 100; done;
or
Code:
while true; do echo 0 > ${ac}; echo 1 > ${ac}; done;
effect is the same. When I connect piezo to the oscillator, it works okay. I suspect there is some capacitor connected to the port in Kindle. If so, it would be hard to get higher frequencies out of the port.
New bad news: while writing this post I discovered I can hear ticks (about 5 per sec) on the piezo while the port is on. Also, I can hear eink updates clearly (try with while true; do eips -f ''; done) and I think wifi too! When I hold enter in the SSH, I can hear background noise.
