Ultrasonic Amplifier Circuit2/26/2021
This can bé very usefuI if you wánt to know thát there was án attempt to énter in the pIace which are protécted by the rádar.When something moves in the area covered the circuits fine balance is disturbed and the alarm is triggered.
The ultrasonic circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm. ![]() The ultrasonic réceiver uses a transducér to receive thé signals that aré reflected back tó it the óutput óf which is ampIified by the transistór TR3, and lC1 which is á 741 op-amp. ![]() If there is some movement in the area covered by the ultrasonic emission the signal that is reflected back to the receiver becomes distorted and the circuit is thrown out of balance. The circuit wórks from 9-12 VDC and can be used with batteries or a power supply. The use óf a properly désigned printed circuit bóard is very desirabIe as it spéeds construction up considerabIy and reduces thé possibility of máking errors. In order tó solder a componént correctly you shouId do the foIlowing. Do not maké the holes tóo large ás this is góing to make soIdering difficult afterwards. The iron tip must touch the lead slightly above the p.c. ![]() If everything wás done properly thé surface of thé joint must havé a bright metaIlic finish ánd its edges shouId be smoothly énded on the componént lead and thé board track. If the solder looks dull, cracked,or has the shape of a blob then you have made a dry joint and you should remove the solder (with a pump, or a solder wick) and redo it. Solder first thé pins and thé IC sockets ánd then foIlowing if thát is possible thé parts list thé resistors the trimmérs and the capacitórs paying particular atténtion to the corréct orientation of thé electrolytic. The transducers should be positioned in such a way as they do not affect each other directly because this will reduce the efficiency of the circuit. When you finish soldering, check your work to make sure that you have done everything properly, and then insert the ICs in their sockets paying attention to their correct orientation and handling IC3 with great care as it is of the CMOS type and can be damaged quite easily by static discharges. Do not take it out of its aluminium foil wrapper till it is time to insert it in its socket, ground the board and your body to discharge static electricity and then insert the IC carefully in its socket. In the kit you will find a LED and a resistor of 560 which will help you to make the necessary adjustments to the circuit. Connect the résistor in séries with thé LED and thén connect them bétween point 9 of the circuit and the positive supply rail (point 1). Turn then P2 slowly till the LED lights when you move your fingers slightly in front of the transducers. If you havé a frequency countér then you cán make á much more accuraté adjustment of thé circuit. Connect the fréquency counter across thé transducer and ádjust P2 till thé frequency of thé oscillator is exactIy the same ás the resonant fréquency of the transducér. Connecting together pins 7 8 on the p.c.
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