Geoffrey S. Mendelson wrote:
As for the controllers, the question is exactly how "off the shelf" do
they need to be? If you have someone on the project who can figure out
how to add the switching logic and a someone to modify the operating
system for you, discarded iPods would be perfect. There are lots of
them lying in drawers, being too good to throw out and too expensive
to fix (mostly battery replacement).

After I wrote this I was looking through an old magazine and found a
cicruit to take the output of a tape recorder and use it to key
a transmitter. This one used a single transistor and a relay.

I would update it a bit and instead of using a tape recorder, I
would use a small MP3 player. The kind that use a single AAA battery,
and look like a package of chewing gum sticks.

If you modify them to run from external power, will run for almost a day
on a high capacity AA rechargable battery.

If you create an MP3 file with what you want on it at a low enough bit
rate for "telephone" quality, it would run for an hour on 10 megabytes
of memory. E.g. a 256 megabyte unit will run for 25 hours.

Some of them will play the same file over and over, so you can loop
from when you hit the start button until the battery dies.

The cost is low, WalMart's website has them with 1gigbyte of
memory for $25 and I'm sure you can find 64megabyte ones
very cheap, or even used for free. Since they all would have
the same connection, a headphone jack, getting duplicates
would not be a requirement.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
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