On Tue, 2007-09-18 at 22:33 -0400, Bill Sudbrink wrote:
woodelf wrote:
Bill Sudbrink wrote:
1) The manual calls for a 45 Ohm QUAM speaker.
All I have
are plain old run-of-the-mill 8 Ohm internal PC speakers.
My ignorance of basic electronics shines through...
30 minutes of googling and I'm not sure what QUAM means.
Anyway, can I substitute the speaker? With some modification
to the schematic?
I think B.G. micro has 45 ish ohm speakers.
They tend to be used in intercoms often I think as the microphone
or speaker.
OK, I see 32 Ohm (what's 13 Ohms between friends?)...
the price is right. Are they QUAM?
32 should be fine. You could also stick a load resistor of about 47
ohms in place, and feed the output to an external amplifier.
The main reason for 45 ohms is probably because the speaker driver is
just a simple transistor driven by an IO pin somewhere. If you used and
8 ohm speaker it would draw too much current and fry the tranny (and
possibly pull the 5v rail down as well).
Gordon