audiometer

Testing and Discussion

Testing of the circuit is carried out on the completion of each part of the circuit. Firstly the vco was tested then the phase detector and low pass filter along with the subtractor. Graphs and tables will be provided over the next few pages to demonstrate exactly how each part of the circuit was tested. Two main types of equipment were used while testing; these were an oscilloscope and a multimeter. To test the circuit negative voltages were required in some parts of the circuit. How these were obtained will be shown in diagram form.


Voltage controlled oscillator

The vco was built in three separate parts to facilitate testing. The first part constructed was the comparator circuit with three 1k resistors. A 0 to 6 volt line was feed into two of the inputs of the comparators as shown below.
The 1K resistors drop the voltage of the Vcc from 6v too 4v and 2v at points A and B respectively, due to Kirchoff’s potential divider rule, “ VR = (R/Rt)*Vs...