LASER DATA COMMUNICATION AND CONTROL SYSTEM.
By using this portion with laser communication, we can control different electrical or electronics equipments with the help of the control signal. In communication circuit we use one dtmf decoder circuit. In that dtmf decoder circuit we use ic 8870 as a dtmf decoder circuit and one ic 7447 as a bcd to seven segment decoder.
We use one another dtmf decoder circuit, ic 8870 decoder and sense the output in the form of the bcd signal from the dtmf decoder circuit.
IN this block diagram we show that how we control the many electrical appliances with the help of the control circuit.
Signal from the op-amp is connected in parallel with the display circuit to the control circuit. Output from the mike amplifier is connected to the 8870 decoder circuit.
Input signal from the op-amp is connected pin no 2 and 3 of the of the 8870 decoder and output is available on the pin no 11,12,13,14 of the ic 8870 . Flash signal is available on the pin no 15 of the ic 8870 and this signal is further switch on the npn transistor. Collector of the npn transistor is connected to the pin no 18 and 19 of the ic 74154. One resistance and capacitor is connected to the pin no 17 and 18 of the ic 8870 is reset the ic 8870. Output of the 8870 is connected to the pin no 22,23,21,20 of the ic 74154. Pin no 12 of the ic 74154 is connected to the negative of the circuit and pin no 24 of the ic is connected to the positive supply of the circuit.. Pin no 18 and 19 of the ic is enable control pin. It means that when we apply a negative voltage to this pin then ic provide a output in decimal form. IC 74154 is basically a bcd to decimal decoder. Output from the decoder is connected is in negative form and we use one inverter circuit to convert this negative output to positive output.. Here we use two ic 4049 as a inverter ic . IC 4049 contains total six inverter inside . Output available on the output of the ic 74154 is total 10 output, so we use total two ic to convert 10 outputs from the decoder.
Pin no 16 is connected to the positive supply and pin no 8 is connected to the negative supply of the circuit.. Output from the ic 4049 is next connected to the d type flip flop circuit to switch on/off any electrical circuit . For this purpose we use ic 4013. Ic 4013 is a flip flop circuit and dual flip flop circuit. In dual flip-flop.
Pin no 14 is the positive supply and pin no 7 is the negative supply. Pin no 3 and pin no 11 is the input clock pulse of the ic 4013. Pin no 1 and pin no 13 is the output pin of q output, we never use a Output from pin no 2 and pin no 12. . when positive data is available on the pin no 1 then pin no 2 is become negative and this time this pin no 2 is connected to the data input pin 5. Now data is available on the pin no 5 is negative and when again we provide a clock pulse then negative data is avaialbel on the pin no 1 and output circuit is connected to the pin no 1 is on and off.
Output available on the output is digital output, so to interface this output to the electrical circuit we require a triac or relay driver circuit.
For this purpose we use one l.e.d and transistor circuit in series to the output of the flip flop. When output is on then flip flop is on and then relay connected to the circuit is automatically and pass the 220 volt to the load circuit and due to this electrical circuit is on.
Main component of this project is laser diode. A laser diode needs a certain value of current, called the threshold current, before it emits laser light. A further increase in this current produces a greater light output. The relationship between output power and current in a laser diode is very linear, once the current is above the threshold, giving a low distortion when the beam is amplitude modulated. For example, the 65Onm 5mW laser diode used in this project has a typical threshold current of 3OmA and produces its full output when the current is raised by approximately 1OmA above the threshold to 4OmA. Further increasing the current will greatly reduce the life of the laser diode, and exceeding the absolute maximum of 8OmA will destroy it instantly. Laser diodes are very fragile and will not survive electrostatic discharges and momentary surges!
Transformer 9v 500mA
LASER he-Ne 5mm
Seven segment display
Capacitors- 0.1microfarad,00.1 microfarad,1000µf,470µf
Cupper clad board