I have a 9V battery powered circuit that we use to help kids learn about the brain. Students place two pins into a living cockroach leg, and my circuit amplifies the electrical "spikes" in the leg. A photo of the finished product (without a cockroach leg)
It works, but the speaker is not nearly loud enough. I am trying to debug it carefully to see what the outputs of each of the stages are. I am suspecting there might be a DC offset that is being amplified, and clipping the signal. I only have a Tektronix oscilliscope that plugs into the wall. When I hook up the probe to the circuit with a leg on it, it distorts the signal badly.
Are there tips to see what is happening within the circuit? Also, any kind suggestions for improvement would be very much appreciated. Schematic is attached.
Thank you, Greg
It works, but the speaker is not nearly loud enough. I am trying to debug it carefully to see what the outputs of each of the stages are. I am suspecting there might be a DC offset that is being amplified, and clipping the signal. I only have a Tektronix oscilliscope that plugs into the wall. When I hook up the probe to the circuit with a leg on it, it distorts the signal badly.
Are there tips to see what is happening within the circuit? Also, any kind suggestions for improvement would be very much appreciated. Schematic is attached.
Thank you, Greg
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