A signal generator is handy to have around the lab. It’s perfect for testing inputs on a new hardware design; use it with an oscilloscope to verify the behavior of your circuit. Turn a smartphone into one for less than $15!
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Generate a signal to test a circuit.
Now that you have the signal generator working, try building a simple low-pass filter using a 1k ohm resistor connected to a 0.1 uF capacitor that then connects to ground. Vary the frequency and watch how the signal output between the resistor and capacitor is filtered below 1500 Hz!
Test your speakers.
Try connecting it to a speaker. Adjust the signal level and the type of signal generating (square vs sine). Adjust the frequency. Do you notice any differences? If you want to increase the output to the speaker (gain) adjust the resistor value in the op-amp protection circuit so that the gain is no longer one (unity).
Generate audio tones.
Try generating different frequency tones. What is the minimum frequency you are able to generate? What is the maximum? At what point can you no longer hear the audio being generated?
Troubleshoot a malfunctioning circuit or device.
Try troubleshooting a malfunctioning circuit or device. Disconnect the input of the circuit and connect the signal generator instead. Setup the generator to output the type of signal, frequency and signal level that would normally be input to the device. Now start debugging!
Experiment with a circuit. (signal into an op amp for gain and frequency response measurements)
Try building a high and low pass filter using an op-amp. You can sweep through the different frequencies and record the voltage output every 1 KHz. If you plot the data how does the response look?
For an example of a circuit, visit makezine.com/go/buffercircuit.
This project first appeared in MAKE Volume 36, page 115.
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