- Jan 1, 1970
I have a couple of 10sec sound recorder boards from toys that I wish
to connect to a single speaker. At the moment I have a breadboard with
a 16F84 PIC powering each board seperately via transistors before
triggering its PLAY connection, waiting a specified time period for
the sound to play then shutting it down. The problem is that the
boards have their own speaker connections running back to a gob-top
chip and if I have them both connected to an 8ohm 0.25 watt speaker
the playback sound is degraded. Connected seperately to the speaker
they're fine but with even only one wire from either of the other
boards speaker connections hooked up then the sound degrades powered
up or not.
The only way I can think of to solve this is a couple of PIC
controlled 5V DPDT relays, one for each pair of speaker wires. That
seems messy and though small the relays make an audiable click
especially when mounted.
Can anyone suggest another hopefully less complicated way to stop this
Any help is always appreciated.
The problem is likely because the low impedance output of the unuised
recorder is essentially shorting the speaker. One possible simple
solution (if you can tolerate a small volume degradation) is to put a
8-ohm resistor is series with each output. This will attenuate the
signal at the speaker (because of the divider from the in-use device,
and the 8-ohm shunt of the unused device), but should maintain the