I'm working through Experiment 11 of Make: Electronics (1st edition since I bought a component kit that matches that edition).

I have the circuit configured below, but I'm not sure that the loudspeaker is doing what it's supposed to do. The book describes the sound as an "insect buzz". What I'm hearing is more of a "tick tick tick".

What really makes me think this is wrong is when I read Step 4:

If you wanted to use this audio signal as some kind of an alarm, a steady droning noise is not very satisfactory. A pulsing output would be a much better attention-getter.

The sound I'm getting already sounds more like a pulsing output and less like a steady droning noise!

Here's a video of it where you can hear the sound. https://youtu.be/Mv8m_5eydJs

Can someone tell me if that's right? Or is my speaker connected wrong or malfunctioning?

(I did have a hard time connecting the wire to the speaker's terminals. I had to use alligator clips and I'm worried something might be touching the housing of the speaker)

Update: I forgot to post the diagram Experiment 11 Diagram

  • 1
    \$\begingroup\$ That is not correct. It is likely either a connection problem or maybe the voltage fed into the speaker is too low of a frequency. How are you driving the speaker? \$\endgroup\$ Commented Apr 9, 2021 at 3:26
  • \$\begingroup\$ Good for a metronome, and very slow relaxation pulse oscillator. Show all details, power, ground circuit, layout. Voltages on schematic...Watch out for positive feedback. \$\endgroup\$ Commented Apr 9, 2021 at 3:38

1 Answer 1


You probably have one of the resistors or capacitors substituted for a value that's about 1000 times too high.

  • \$\begingroup\$ That was it. I had a 2.2μF capacitor as C2 instead of a 0.0047μF. Thanks! \$\endgroup\$ Commented Apr 11, 2021 at 15:50

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