gistfile1.txt

Yes, you're on the right track with your proposed circuit design. You'll want to implement a high-pass filter in your conditioning/amplifier circuit to isolate the knock frequency of interest (around 7.6 kHz). This will help eliminate unwanted low-frequency noise that could falsely trigger your knock control system.

Here's an outline of your circuit with the high-pass filter included:

Input protection: Use a TVS diode with a breakdown voltage slightly above the max voltage to protect against voltage spikes.
High-pass filter: Implement a high-pass filter to isolate the knock frequency (around 7.6 kHz). This can be done using a passive RC filter or an active filter with an operational amplifier (op-amp). The choice will depend on your requirements and available components.
Rectifier stage: Use a full-bridge rectifier to convert both positive and negative AC voltage signals into a positive DC voltage.
Amplification stage: Use a non-inverting amplifier with an op-amp to amplify the filtered and rectified signal.
Output protection: Use a 5V Zener diode connected to ground to protect the output from exceeding the 5V limit of the MegaSquirt 2 analog input.
When designing the high-pass filter, you will need to calculate the appropriate component values for the desired cutoff frequency (7.6 kHz). For a passive RC filter, you can use the following formula:

f_c = 1 / (2 * π * R * C)

where f_c is the cutoff frequency, R is the resistor value, and C is the capacitor value. For an active filter, you may need to consult the specific op-amp configuration's design equations.

Once you've designed and built the circuit, test it with a known knock signal to ensure that it functions correctly and provides a reliable connection to the MegaSquirt 2. After successful testing, you can integrate it into your knock control system.