Home Projects Oscillators and timers 1KHz Sinewave Generator

 

 

1KHz Sinewave Generator

source: RED Free Circuit Designs

Simple circuitry, low distortion, battery operated

Variable, low impedance output up to 1V RMS

 


1KHz Sinewave gen. circuit diagram



Parts:

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__________100F  25V Electrolytic Capacitor
C4__________470nF  63V Polyester Capacitor

Q1,Q2_______BC238  25V 100mA NPN Transistors

LP1___________12V  40mA Lamp (See Notes)

J1__________Phono chassis Socket

SW1__________SPST  Slider Switch

B1_____________9V  PP3

Clip for 9V PP3 Battery



Circuit description:

This circuit generates a good 1KHz sinewave using the inverted Wien bridge configuration (C1-R3 & C2-R4). Features a variable output, low distortion and low output impedance in order to obtain good overload capability. A small filament lamp ensures a stable long term output amplitude waveform. Useful to test the Audio Millivoltmeter, Audio Power Meter and other audio circuits published in this site.

Notes:

  • The lamp must be a low current type (12V 40-50mA or 6V 50mA) in order to obtain good long term stability and low distortion.

  • Distortion @ 1V RMS output is 0.15% with a 12V 40mA lamp, raising to 0.5% with a 12V 100mA one.

  • Using a lamp differing from specifications may require a change in R6 value to 220 or 150 Ohms to ensure proper circuit's oscillation.

  • Set R5 to read 1V RMS on an Audio Millivoltmeter connected to the output with R7 fully clockwise, or to view a sinewave of 2.828V Peak-to-Peak on the oscilloscope.

  • With C1,C2 = 100nF the frequency generated is 100Hz and with C1,C2 = 1nF frequency is 10KHz but R5 is needing adjustment.

  • High gain transistors preferred for better performance.

 
 

 

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