Self Powered Sine to Square wave Converter. Circuit Diagram: Components: Theory: R1 1M 1/4W Resistor R2 100K Linear Potentiometer The capacitor C3 blocks any voltage due to the voltage doubler C1,C2 100µF 25V Electrolytic Capacitors circuit hence allowing only AC signal to pass through C3 10nF 63V Polyester Capacitor D1,D2 1N4148 75V 150mA Diodes IC1 4069 Hex Inverter IC. Introduction: . The Self powered Sine to Square wave converter is intended to High Input Impedance. provide good square waves converting a sine wave picked up from an existing generator. Its main feature consists in the fact that no power source is needed, thus it can be simply connected between a The above schematic is with reference to ICA. This amplifies the sine wave generator and the device under test. input signal. The value R1=10M is replaced by 1M according to the amplification required. The resistor R1 also limits the gain of the inverter. Working: The above circuit converts a sine wave input into a square wave IC4069 Hex Inverter: with requirement of no power source. A voltage doubler is formed by capacitors C1,C2 and diodes D1 and D2. The circuit makes use of a Hex Inverter 4069 IC which is powered by the voltage doubler. The ICA amplifies the input sine wave, other inverters included in IC1 squaring the signal and delivering an output wave of marks/space ratio and good rise and fall times through the entire 20Hz-20KHz range. The output square wave amplitude is proportional to input amplitude. Working of Voltage Doubler Circuit: During the Positive half cycle of the input signal, diode D1 is reverse biased, diode D2 is forward biased and the input voltage charges the capacitor C2 up to peak rectified voltage (Vin) Vc2=Vin--------1. During the negative half cycle of the input signal, diode D2 is The circuit makes use of IC 4069 Hex Inverter of type CD4069UBE. reverse and D1 is forward biased. Diode D1 is ideally short during It consists of six CMOS inverter circuits. this half cycle. By KVL, we get, The driving voltages Vdd and Vss required for the working of the Vin+Vc2-Vc1=0--------2. MOSfet is given by the voltage across the capacitor C2 as shown in But Vc2=Vin. the circuit diagram. Hence Vc1=2Vin Applications: In today's modern world, a square timing signal is the most basic signal required in a number of applications. Be it a basic 8085 microprocessor or the modern day Pentium 4 processor all require a timing square wave pulse. As we all know, no natural oscillator can produce a square wave. All oscillators produce sine waves. Thus we require converting these sine waves into square waves before using. Schematic of one inverter Limitations: Features of CD4069UBE: Standardized Symmetrical output characteristics. Minimum sine wave input amplitude needed for good performance 100% tested for quiescent current at 20V. is 750mV RMS Maximum input current of 1μAat 18Vover full package temperature range; 100nA at 18Vand 25ºC. Applications: Logic Inversion. Pulse shaping. Oscillators. High input impedance amplifiers. The supply voltage range should be between 3V to 18V for maximum reliability. Maximum Ratings: D.C. supply voltage range referenced to Vss -0.5V to +20V terminal. Input voltage range(All inputs) -0.5V to Vdd+20V D.C. input current, any one input +10mA Operating temperature range(TA) -55ºC to +125ºC Storage temperature range(Tstg) -65ºC to +150ºC Lead temperature(During soldering) +265ºC At a distance of (1.59 + 0.79mm.)from case to 10s max Troubleshooting: 1) Unlike the given circuit, the actual circuit needs high value for capacitor C2, because the IC consumes more current due to which capacitor cannot retain the charges stored in it and starts discharging. This eventually reduces the amplitude of the square wave in the output up to zero as the capacitor gets completely discharged. To rectify this up to some extent, we connected a capacitor of 100μF in parallel with C2 thus a total capacitance of 200μF is used in the circuit 2) The potentiometer should be set at maximum value to obtain a clear square wave output.
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