A question about Experiment 11 in Make: Electronics (2nd edition)

Question

I have been trying to complete Experiment #11 in the Make Electronics Book, second edition. I was able to get the oscillator working with the lights, but have not been able to get the speaker working. I have tried multiple speakers, etc. I bought the kit so I think the components are probably correct.

Any way to test each part of the circuit? It seems the voltage fluctuates during the oscillation so it makes it tougher to troubleshoot.

jw0752 · Answer

Hi David, Unless I am missing something your assembly looks good. What size capacitors are you using in the astable multivibrator circuit. Once possibility is that the oscillation is above the frequency range of the speaker. Have you tested the speaker by briefly putting a 1.5 volt battery across it to see if it clicks? You could go back to the LED set up to see if that is still working. If it is then install the speaker again without changing the capacitors. Instead of a flashing LED you should hear a click, click, click in the speaker. If you can get that working gradually decrease the size of the caps to hear the clicking increase in frequency. The best part of this exercise is that it is not working which will force you to solve the problem and in the course you will learn more than if it had worked the first time around. Keep up the good work, the fun is really in beating the challenge of things that don't work as expected. Also if you do solve the problem please get back to me as now I am interested, John

david_brehm · Answer

Success! I rebuilt the circuit again on a second breadboard and got it to work. Then I went back to the original breadboard and found a bad transistor. I have been making a lot of progress in learning about electronics -- fixed my first vintage receiver. Thank you so much for your help and guidance. David Brehm

A question about Experiment 11 in Make: Electronics (2nd edition)

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