| Author | Message | ||
     yo_tyler |
i have an old (compaq cotura 4/25...4M of ram 25mhz) laptop without a mic or speakers, is it possible ,with some software and/or hardware to send the sound through the serial or paralell port? | ||
| Simon Quellen Field (Sfield) |
The answer is yes, but you will probably have to build it yourself. The trouble and expense will probably not be justified over just upgrading to a new computer. Unless you write a device driver that mimics a sound card, the standard software for playing music and speach will not work with your setup, and you will have to write that software as well. If you have those skills, you can trade your efforts for a new computer. | ||
| mark |
I did this years ago using the printer port (Connected to the 8 data lines), here's how:  The idea is that using your own computer program (example: in qbasic' the command is (out &h378,xxx) where xxx is the 8 bit number in binary to turn on each of the data pins 0 being all off 255 being all on) you turn on and off the pins the more you turn on the more voltage appears on the output. The capacitor makes sure that only rapidly changing voltages go through, (but if you wanted a fixed dc votage level from 0-5v you could remove the capacitor). | ||
| mark |
(The capacitor goes on the output, and the resistor values 1R=470ohm 2R Approx twice that) | ||
| yo_tyler |
mark, thx for your post, but how do i get sound via this "thing" above? ps: i use QBasic and just learning C++. | ||
| Simon Quellen Field (Sfield) |
Note that your original question was about using a serial port, and this project uses a parallel port. The D0, D1, etc are pins on the parallel port. These are pins 2 through 9 respectively. See here for a picture. The symbol on the bottom right is called "ground", and on the parallel port pins 18 through 25 are all connected to ground, so you can use any or all of them (suggestion: use pin 25). The speaker is connected to ground on one side, and to the place on the schematic marked with a little circle and triangle on the other side. The problem with this kind of circuit is that it depends on the computer being able to send data to the parallel port on a predictable and reliable schedule. But the program you are going to write is running along with other programs and services, and will not always be able to update the parallel port at the right time. This will lead to noise in the output. In the old days before modern operating systems, people used DOS which didn't do much when your program was running, allowing the program to more reliably schedule the parallel port updates. | ||
| Michael Fincham Unregistered guest |
There's a driver for Windows 95 and/or Windows 3.1 that'll drive this, Google for "covox speech thing" I believe. |
