1kHz Ultra Low Distortion Oscillator Module for Arduino Projects

This is an extreamly low distortion 1 kHz oscillator module for Arduino controlled projects.

The module will be used in my ref. signal source design.

Supplies

Main parts:

Opamps: LT1115 - LT1638 - OPA2134

FET: 2N4391

The BurrBrown OPA2134 is critical for the distortion specification.

To get 1kHz very precise C1, C2, R2, R7 must be selected very carefull.

Step 1:

The measured specification of the module:

Frequency:           1036 Hz (before using selected parts for C1, C2, R2, R7)

Signal level:          1000 mV rms / 0dB

Distortion:             0.0003% / - 111dB

Signal/noise:          - 91.1 dB

Step 2: The Circuit

The design is based on a state variable oscillator.

(Ref.: http://vkaudiotest.co.uk/ --- BUT this link is no longer active and I have not been able to find the original circuit designer).

The circuit diagram: there are 3 main circuits. The state variable oscillator, full wave rectifier and the precision signal stabilization circuit.

Step 3: PCB Design

The PCB layout for the module is based on my prefered dimensions for modules. The modules will be build in a standard Hammond box.

Step 4: Whats Next

This is the project where the 1khz module is used.

More to come of the design of the complete test equipment.

The intention on the test equipment: Testing of audio equipment