Experiment 17: The astable mode of the 555 timer

Last weekend I had a chance to continue with the next experiment. Make:Electronics suggests to set it up on the same breadboard that still has experiment 16 on it. This is for later experiments when the 555 timers will be chained. Again this is an easy experiment although I almost forgot all important connection between pin 6 (threshold) to pin 2 (trigger). Instead of one pulse in the monostable mode a stream of pulses is generated. The loudspeaker that is connected to the pin 3 (output) generates a (faint) tone. According to the book it is 1,5KHz (this equals to 1500 pulses per second).

Overview of breadboard with on top experiment 16 (with led and potentiometer) and beneath it experiment 17 with the speaker on the side

Close-up of experiment 17 (bottom IC)