basic recordings. As shown in Figure 5-13, click on “Start,” then “Programs,” then “Accessories,” then “Entertainment,” and finally on the program called “Sound Recorder.”
This sound recording program is as basic as it gets, but will be more than enough to record whatever horrific yelps, screams, or barks you want to use to wake your slumbering pals up in a hurry. You can even add a bit of echo, or slow the sound down to make it sound like it came spewing from an evil demon by lowering the pitch of the recording. The sound recorder program will open a tiny window with a few options such as record, effects and file functions. Go ahead and click on the record button as shown in Figure 5-14 to start recording sound from your microphone.
Any sound heard by the microphone will be translated into a wave shape in the little sound recording window as shown in Figure 5-14, as I cackle and grumble into my microphone, reciting my favorite lines from the Evil Deadtrilogies for later playback. If your microphone is properly connected and your volume control set to monitor the correct input, then you should see a nice saturated wave file as you speak into the microphone at a moderate level. If something isn’t connected correctly, then your PC’s hard disk drive is probably laying on the other side of your room in a large plume of smoke as the rest of the computer incinerates in a huge red fireball. No seriously, unless you are in the wrong input
plug, everything should be working fine, but if there is no modulation in the sound recorders window, simply try the other input lugs until you see something. If that does not help, re-check the record input control to ensure that the microphone input is selected and cranked up. Practice making the most terrible sounds you possibly can, maybe throwing in a bit of echo, or a pitch drop to mess things up to the max, and then save one of the sounds using the “Save” commands on the menu bar. Save the file to a place on your hard disk that is easy to find, since we are now going to run the scheduling tool to trigger it. As shown in Figure 5-15, the path to the built-in “task scheduler” is a long one, but I assure you that every version of Windows has one of these applications, and it will let you run any program, sound or video file that your mouse can click on, and it will do it at any time you tell it to.
On XP, the program is called “Scheduled Tasks,” and will bring up a new window like the one
Project 18—Computer Audio Nightmare
Figure 5-13 Running the basic operating system sound record program
shown in Figure 5-16. All you have to do in order to schedule the sound to play at some specific time is to click on “Add Scheduled Task,” then
“Browse,” and then locate the sound file you have just saved, and click on it. In Figure 5-16, I have selected the file “FBI-Raid.wav” as the sound file that will be blasted through the house at wee hours of the night on volume levels that will make it sound as though it were really happening.
Normally, the task scheduler would be used to trigger an application, but you can choose a sound file due to the fact that your operating system will spawn whatever program is associated with the sound file to play it back. Basically, whatever happens when you click on any file with your mouse pointer is what will happen if you choose it as the target for the task
scheduler program. The only step left is to set the time you want the event to happen as shown in Figure 5-17.
You can set the event to occur only once (recommended), or at any given interval if you like, and then the actual time is entered in the last box as shown in Figure 5-17. Once you select a time, press “Next,” and the task will be set to run as long as your PC is powered up when the chosen time comes around. You might want to choose a time such as 1 minute from now just to test your volume and make sure the sound is going to trigger properly, as you can always reschedule the event again by right clicking on it and entering another time. Now your PC is ready to scare the wits out of your buddy in the middle of the night—a true computer audio nightmare indeed!
Project 18—Computer Audio Nightmare
Project 18—Computer Audio Nightmare
Figure 5-16 Scheduling a sound file for later playback
If you have ever had a furry little critter invade your home, then you are probably familiar with the aggravating sounds that the little rodents make in your walls at night as they scurry about. Well, this little device will closely simulate the same sound a mouse or rat would make in a wall, and will only operate at night, so it’s very difficult to track down. Even the light of a flashlight will make the device go silent, so your unsuspecting victim’s rodent hunting expedition will likely fail. This project uses a 555 timer set up as an oscillator that drives its output into a small open-core electromagnet in order to vibrate a tiny permanent magnet floating inside the coil. The result is a random sound resembling the sounds that a small animal would make as it gnaws at wood or some other hard material. For this project, you will need some thin, enameled, copper wire to wind an open core coil. This copper wire can be found in any small transformer, toy motor, solenoid, relay and many other small electromagnet devices. You can also purchase spools of this wire at many hobby shops for a few dollars. The exact size of the wire is not all that important. Figure 5-18 shows some copper
wire I salvaged from an old solenoid and a tiny square magnet taken from a magnetic name plate of some sort. The magnet only needs to be the size of an aspirin, or even a fragment of another larger magnet since its only job is to rattle around a bit.
To wind the coil, find a cylindrical object slightly larger than the magnet with a smooth surface so you can wind the coil and then slide if off easily when completed. For my magnet, an AA battery was the perfect size, and would allow the wound coil to be slid off without any trouble. You will want at least 150 turns in your coil, and if you have a lot of wire, use 200 or more turns. This may seem like a lot of wire, but 150 turns is only about 20 feet of wire, and it takes less than a minute to make the entire coil. Wind the wire tightly, and leave at least 6 inches at both ends so you can make the connection to your circuit board. Figure 5-19 shows the completely wound 150 turn coil ready to be slid from the battery used as a form.
Be careful when you remove the coil from the form, as it may tend to unravel once the form is no longer holding it tightly together. As shown in Figure 5-20, a few turns around each side of the coil using some of the leftover copper wire will hold the unit together so you can handle it without it unwrapping. Now you can test your coil and magnet by placing the magnet into the center of