Thursday, April 1, 2010

Function Generator

The FunGen Function Generator design utilises the Exar 2206 IC to produce Sine, Triangle and Square waves with adjustable frequency. Its features include:
Output Waveforms: TTL Square Wave and selectable Sine or Triangle Wave
Output Amplitude: Square Wave: TTL Output, Sine/Triangle: 0Vp-p to approximately 6Vp-p.
Output Frequency: 25Hz to over 250kHz 

The design includes a buffered virtual ground circuit provided by an LM741, LM318 or similar Op Amp, which sets a fixed voltage half way between the input voltage and ground. This is then used as the virtual ground for the sine and triangle wave outputs from the "WAVE_OUT" connector, providing an output centred around 0V.

A 74HC04 or 74LS04 Hex Inverter is used to buffer the Square Wave output, decreasing the rise and fall time of the square wave output.

The amplitude and frequency adjustment pots are mounted on the board for easy adjustment. An ON/OFF switch, Waveform selector switch and Frequency range switch are also mounted on the board.


Components Required:
IC1,   XR2206 
IC3,   LM741 or LM318 Op Amp
IC2,   74xx04 Hex Inverter
IC4,   LM7812
IC5,   LM78L05
C1,   100uF (or 10uF) Capacitor
C2,C5,C6,C7,C10,  1uF Capacitor
C3,C4,   0.1uF Capacitor
C8,   0.22uF Capacitor
C9,   2.2nF Capacitor
D1,   1N4001 Diode
R4,   200Ω 1% Resistor
R1,R5,R7,   1kΩ Resistor
R2,R3,R6,   10kΩ Resistor
R8,R9,   100 Ω Resistor (optional)
pot1, pot3,   50kΩ Pot
pot2,   250kΩ Pot
two Sliding Switches
3mm or 5mm LED
two,   Dual Screw Terminal