SparkFun Forums

[mzoran]

Is it possible to play music with the SFE COM-07950( CEM-1203 )? I've been able to play simple square waves but sin waves and arbitrary waveforms don't seem to work. Is this beyond the limitations of this device?

Here is my setup:

( PWM Output) ( Low Pass Filter ) ( OP-AMP for Buffering)
PIC18f2550(CCP1) - 580Ohm resistor - LM358(Voltage Follower) - CEM
| |
0.1uF Cap |
| |
GND GND

When the CEM is disconnected I can see on the oscilloscope that the output is indeed a sin wave of the correct frequency., but when the CEM is connected the waves all have the top cut off like the signal is saturating.

The ultimate goal is to be able to play arbitrary sampled music and sound effects.

If this device can't do it, does anybody know of a small speaker that's of comparable size that can play arbitrary sound. Searching on Digikey is sometimes a crapshoot.

[mzoran]

Looks like something formated my diagram. The resistor and cap are configured as a simple low pass RC circuit with the op-amp as a unity gain buffer. One terminal of the CEM(+) is connected directly to the op-amp output and the negative terminal is connected to GND.

Thanks much.

[jasonharper]

That buzzer is a resonant device, intended only for producing tones near its rated frequency of 2048 Hz. Other notes are going to drop off in amplitude as you get further from that frequency.

For arbitrary sounds in a small size, a piezo speaker is probably what you want, but I don't know any specific part numbers to recommend.