Sine Wave Generator (1KHz Frequency)

This is iKHz sine wave generator circuit built based on configuration of inverted Wien bridge (see C1-R3 & C2-R4). R5 and R7 used for output amplutide setting. Set R5 to read 1V RMS on an Audio Millivoltmeter connected to the output with R7 rotated fully clockwise, or to view a sinewave of 2.828V Peak-to-Peak amplitude on the oscilloscope.

Component list:

R1____________5K6  1/4W Resistor
R2____________1K8  1/4W Resistor
R3,R4________15K   1/4W Resistors
R5__________500R   1/2W Trimmer Cermet
R6__________330R   1/4W Resistor
R7__________470R   Linear Potentiometer

C1,C2________10nF  63V Polyester Capacitors
C3__________100µF  25V Electrolytic Capacitor
C4__________470nF  63V Polyester Capacitor

Q1,Q2_______BC238  25V 100mA NPN Transistors
LP1___________12V  40mA Filament Lamp Bulb (See Notes)
J1__________Phono chassis Socket
SW1__________SPST  Slider Switch
B1_____________9V  PP3
Clip for 9V PP3 Battery

Notes:

• The bulb must be a low current type (12V 40-50mA or 6V 50mA) in order to obtain good long term stability and low distortion.
• Using a bulb differing from specifications may require a change of R6 value to 220 or 150 Ohms to ensure proper circuit's oscillation.
• With C1, C2 = 100nF the frequency generated is 100Hz and with C1, C2 = 1nF frequency is 10KHz but R5 requires adjustment.
• High gain transistors are preferred for better performance.