I have 2 circuits of my own design I need to find the signal to noise ratio for but I'm not quite sure how to go about it.
Both circuits are guitar effects. One circuit is a cascaded 2 op amp circuit with an RC filter between op amps and 2 diodes as a voltage swing limiter to ground to clip the inputted signal. The other circuit is a negative feedback arrangement using 2 op amps with a RL and RC filter.
I have the noise data for the op amps but I don't know how to take into consideration the filters, diodes and negative feedback.
I thought I could try measuring the output signal with no inputted signal. There was a noise signal there but the oscilloscope was reading a voltage of 220mV and an incoherent signal. The 220mV also changed as I changed the V/div on the scope from 75mV to about 300mV. For a circuit that only has input signal levels of a few hundred milivolts, something like 220mV seems awfully high?
What's the correct way of working out the SNR?
Both circuits are guitar effects. One circuit is a cascaded 2 op amp circuit with an RC filter between op amps and 2 diodes as a voltage swing limiter to ground to clip the inputted signal. The other circuit is a negative feedback arrangement using 2 op amps with a RL and RC filter.
I have the noise data for the op amps but I don't know how to take into consideration the filters, diodes and negative feedback.
I thought I could try measuring the output signal with no inputted signal. There was a noise signal there but the oscilloscope was reading a voltage of 220mV and an incoherent signal. The 220mV also changed as I changed the V/div on the scope from 75mV to about 300mV. For a circuit that only has input signal levels of a few hundred milivolts, something like 220mV seems awfully high?
What's the correct way of working out the SNR?