[sdiy] simple modules

[John Luciani]

On 2/19/07, gerald stevens <erinys at earthlink.net> wrote:
>
> Hello,
>
> I put up a couple of really simple modules (joystick, AM noise) on my
> webpage:
>
> http://home.earthlink.net/~erinys/tech.htm
>
> I have a question on the joystick module - do you think that I needed the
> output followers? (see schematic) If not, then the circuit is beyond
> simple... even with them it's really simple.

It depends on how much current you plan on drawing from XOUT and YOUT.
Keeping the output followers in the circuit is good design practice allowing
your design to work for a wider range of output currents. I would keep them
in.

>
> One more question - if I want to convert a speaker (current) output to
> line-levels, what is the best way to do this?  At first I figured dropping
> an 8 ohm resistor in place of the speaker and reading the voltage across it
> would work best, but I ended up with a few k ohms.  Since the speaker
> driver is a current source designed for an 8 ohm speaker, why doesn't the
> low resistance work best?

How powerful is the amplifier? How much voltage did you expect to see?
If you put 1W into the resistor you should see 2.8V (P = V^2/R).

(* jcl *)

-- 
http://www.luciani.org