This is a revised version of the analog delay circuit.
You can cascade four identical circuits (for a total of 8 opamps) to obtain a fixed 0.5 msec delay up to 6 or 7 kHz.
This revision has several improvements over the previous circuits, including:
- The basic building block ia a 4th order section instead of a 7th order section, so the resulting response is less affected by component tolerances
- The building block topology has unity gain and does not need a gain recovery stage at the end, therefore being less noisy
- The capacitors are all of the same value, and less different resistor values are needed, therefore making the build easier and less prone to error
In any case this circuit requires precision components, 1% metalfilm resistors and 5% or better capacitors. Failing to do so will result in dips/peaks in the amplitude response which will accumulate if several cascaded stages are used.
