Re: Speech board idea...

> This Star Trek/Space Fury/Etc. Speech board has been bothering me since
> those SPO-250 speech chips seem impossible to find. Have any of you tried
> playing with the ISD (Information Storage Devices) Single Chip Voice
> record/playback chips?

        Are these the same ones that they sell at Radio Shack?
 
> The ISD2500 series offers 8KHz sampling with 60 seconds of voice storage.
> "Messages" are addessable under MCU control. Price in singles is about
> $14, which drops to $12 in 10's.
>
> They store sound as roughly 8-bit samples in an EEPROM array, so sound
> quality *should* be pretty good-- and they include antialiasing and
> smoothing filters. The downside is that they need to be "loaded" with the
> samples from an analog source. (Not a HUGE deal really.)
>
> My idea:
>

<snipped the description of your idea>

        One thing I notice about your scheme is that it is redundant. If the PC samples are good enough, why don't you just Hex dump them (The digital sequences) to an EPROM. Run these puppies through a DAC and a continuous-time lowpass filter, and you've got your speech! Use one of Crystal's DACs and your analog signal out will sound as good as your digital data (Had to get my Crystal plug in :) )

        Of course, you need a controller for this whole thing, but I'll bet your PIC will work just fine for that. You just need to clock the data out of the EPROM when you get some sort of enable signal. Which enable signal you get determines the address of the EPROM. You know your sampling frequency when you make the digital dumps from your PC.

        Probably the reason why you didn't think of this in the first place was cost....you assumed that DACs cost more than those Voice Record/Playback ICs, but I'm not sure that that's true.

        Look into it....Other than than that, your idea sounds pretty cool. Maybe people will actually start buying those Radio Shack chips now (Those seem like the only Radio Shack "special" items that have been around for years!)

Joe
Received on Wed Jun 25 13:30:45 1997