Home Chapter 11 BS2 Amplifying sound
BS2 Amplifying sound

Now try experimenting by playing with different numbers and see if you can find both a patterned sound and a complex random sound in one program.

Now see if you can create a sense of chatter in the work, which sounds like electronic creatures communicating.

There are many other possibilities for working with sound and your BS2. You can use an output of your BS2 to drive a stereo jack as input into a stereo to amplify your compositions. You can use a small relay like those found at Radio Shack to open and close connections on a CD player in order to control when the music plays. You can also use a stereo plug as an output from the stamp and input it into a stereo for a loud sound.

For an exciting community of experimental musical instruments and instrument makers visit http://www.windworld.com and be sure to check out the links page.

Outputting Sound

DTMFOUT and FREQOUT are the two codes used to output sounds with the Basic Stamp. DTMF generates dual-tone, multifrequency tones, which are what you hear when you push your touchtone telephone buttons. The telephone is a network where both machines and humans share the same lines to transmit information, and dual tones are used because it is almost impossible for humans to produce dual tones vocally and mistrigger the phone unless you are a tuvan throat singer.

An audio amplifier circuit can be used to make the most of these two commands. Radio Shack sells a small unit that can be removed from its plastic case and the output from the stamp or other sounds can be interfaced to this though the fidelity will not be very high. This is Model: 277-1008.

You can also use computer powered speakers (that is they have an amplifier built in) to amplify your sounds, though you must make sure they are powered externally. Absolutely DO NOT try to drive a speaker directly from any Stamp pin as you will fry your Stamp.

You can also interface your Stamp to MIDI. 

MIDI, or musical instrument digital interface, is an industry standard that lets computers and musical instruments talk to each other. The BS2 can also be interfaced to MIDI signals and a MIDI plug, however, if the BS2 is processing while MIDI is coming in the data will be lost. This is due to the fact that the BS2 does not support buffered serial communication, so it is not suited to simultaneously receive and transmit MIDI signals.