General Engineering Terms
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P" "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Sinewave Oscillator

A circuit designed to output a sine wave. This particular design uses an operational amplifier.

This circuit, using a minimum amount of parts generates a 10Hz sine wave [based on the component values shown]. The active components are generic devices and may be substituted as required. The passive component values set the frequency and should only be changed if a different frequency is desired. The component out lines or package styles are completely irrelevant to the design. Also see a Cosine Oscillator.

Wein-Bridge SineWave Oscillator circuit
Sinewave Osc

Component Description

The active components used in this circuit are basically general purpose low power parts. The example part numbers could easily be replaced by similar to substitute parts. The zener diode is selected for the maximum voltage level of the output, so any substitute part should use the same zener voltage. However the passive parts set the frequency of operation and should not be substituted. Although any package style could be used, as long as the final value remains the same. The FET is used as a feedback path. The voltage applied to the Gate causes the Drain/Source current to vary which reduces the effective resistance of the 500k resistor in parallel with it.

LM101: General purpose operational amplifier. The most common package style was an 8-pin DIP Package, or 16 pin chip.
Companies making Operational Amplifier ICs.

2N3069: Low Power Field Effect Transistor [N-Channel FET], in a TO-18 Package. Manufacturer Solitron Devices.
Companies making Field Effect Transistors [FET devices].

1N914: Fast switching diode in a DO-35 Case [Through-Hole].
Companies making Diodes [Switching and Reference Diodes].

LM103: Reference diode / Zener diode with voltages between 3.0 and 3.9 volts depending on the dash number appended to the part number.

Circuit Recommendation

In the event that the output from the Op Amp is off-set from the desired voltage level, the output may be shifted using an OpAmp Off-Set Null Adjustment.

No bypass capacitors are shown connected to the voltage supply of the Op Amp, but power supply bypassing should always be used. Low inductance capacitors placed near the body of the device and close to the supply leads is recommended. Short traces between the device and capacitor is also desired. A standard value of 0.01uF should provide adequate filtering of the power line and reduce any noise reaching the device over the power line.

Wien Bridge Oscillator

The sinewave oscillator to the right is another example of a Wien bridge oscillator. This example uses an LM107 operational amplifier and component values to produce a 70Hz sine wave.

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