Repro Cromemco joysticks...
Gordon JC Pearce
gordonjcp at gjcp.net
Wed Sep 19 02:23:19 CDT 2007
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).
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