Project of UltraSonic Radar Circuit Diagram

Simple and easy most liked project with many practical applications in security and alarm systems for homes, shops and cars. It consists of a set of ultrasonic receiver and transmitter which operate at the same frequency. When something moves in the area covered by the delicate circuit circuit balance is disturbed and the alarm is activated. The circuit is very sensitive and can be set to zero automatically or to stay on until manually reset after an alarm.

Technical Specifications - Characteristics
Working voltage: 12V DC
Current: 30 mA

How it Works
As it has already been stated the circuit consists of an ultrasonic transmitter and a receiver both of which work at the same frequency. They use ultrasonic piezoelectric transducers as output and input devices respectively and their frequency of operation is determined by the particular devices in use.

The transmitter is built around two NAND gates of the four found in IC3 which are used here wired as inverters and in the particular circuit they form a multivibrator the output of which drives the transducer. The trimmer P2 adjusts the output frequency of the transmitter and for greater efficiency it should be made the same as the frequency of resonance of the transducers in use. The receiver similarly uses a transducer to receive the signals that are reflected back to it the output of which is amplified by the transistor TR3, and IC1 which is a 741 op-amp. The output of IC1 is taken to the non inverting input of IC2 the amplification factor of which is adjusted by means of P1. The circuit is adjusted in such a way as to stay in balance as long the same as the output frequency of the transmitter. 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 output of IC2 changes abruptly and the Schmitt trigger circuit which is built around the remaining two gates in IC3 is triggered. This drives the output transistors TR1,2 which in turn give a signal to the alarm system or if there is a relay connected to the circuit, in series with the collector of TR1, it becomes activated. The circuit works from 9-12 VDC and can be used with batteries or a power supply.

Ultra Sonic Radar Circuit diagram

Construction
First of all let us consider a few basics in building electronic circuits on a printed circuit board. The board is made of a thin insulating material clad with a thin layer of conductive copper that is shaped in such a way as to form the necessary conductors between the various components of the circuit. The use of a properly designed printed circuit board is very desirable as it speeds construction up considerably and reduces the possibility of making errors. Smart Kit boards also come pre-drilled and with the outline of the components and their identification printed on the component side to make construction easier.

To protect the board during storage from oxidation and assure it gets to you in perfect condition the copper is tinned during manufacturing and covered with a special varnish that protects it from getting oxidised and also makes soldering easier. Soldering the components to the board is the only way to build your circuit and from the way you do it depends greatly your success or failure. This work is not very difficult and if you stick to a few rules you should have no problems. The soldering iron that you use must be light and its power should not exceed the 25 Watts. The tip should be fine and must be kept clean at all times.

For this purpose come very handy specially made sponges that are kept wet and from time to time you can wipe the hot tip on them to remove all the residues that tend to accumulate on it. DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many different types of solder in the market and you should choose a good quality one that contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use soldering flux apart from that which is already included in your solder. Too much flux can cause many problems and is one of the main causes of circuit malfunction. If nevertheless you have to use extra flux, as it is the case when you have to tin copper wires, clean it very thoroughly after you finish your work. In order to solder a component correctly you should do the following:
@Clean the component leads with a small piece of emery paper.

@Bend them at the correct distance from the component’s body and insert the component in its place on the board.

@You may find sometimes a component with heavier gauge leads than usual, that are too thick to enter in the holes of the p.c. board.

@In this case use a mini drill to enlarge the holes slightly. Do not make the holes too large as this is going to make soldering difficult afterwards.

@Take the hot iron and place its tip on the component lead while holding the end of the solder wire at the point where the lead emerges from the board. The iron tip must touch the lead slightly above the p.c. board.

@When the solder starts to melt and flow wait till it covers evenly the area around the hole and the flux boils and gets out from underneath the solder. The whole operation should not take more than 5 seconds. Remove the iron and allow the solder to cool naturally without blowing on it or moving the component. If everything was done properly the surface of the joint must have a bright metallic finish and its edges should be smoothly ended on the component lead and the 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.
@Take care not to overheat the tracks as it is very easy to lift them from the board and break them.

@When you are soldering a sensitive component it is good practice to hold the lead from the component side of the board with a pair of long-nose pliers to divert any heat that could possibly damage the component.

@Make sure that you do not use more solder than it is necessary as you are running the risk of short-circuiting adjacent tracks on the board, especially if they are very close together.

@When you finish your work cut off the excess of the component leads and clean the board thoroughly with a suitable solvent to remove all flux residues that may still remain on it.

@There are quite a few components in the circuit and you should be careful to avoid mistakes that will be difficult to trace and repair afterwards. Solder first the pins and the IC sockets and then following if that is possible the parts list the resistors the trimmers and the capacitors paying particular attention to the correct orientation of the electrolytic.

@Solder then the transistors and the diodes taking care not to overheat them during soldering. 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 IC’s 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 resistor in series with the LED and then connect them between point 9 of the circuit and the positive supply rail (point 1).

Connect the power supply across points 1 (+) and 2 (-) of the p.c. board and put P1 at roughly its middle position. Turn then P2 slowly till the LED lights when you move your fingers slightly in front of the transducers. If you have a frequency counter then you can make a much more accurate adjustment of the circuit. Connect the frequency counter across the transducer and adjust P2 till the frequency of the oscillator is exactly the same as the resonant frequency of the transducer. Adjust then P1 for maximum sensitivity. Connecting together pins 7 & 8 on the p.c. board will make the circuit to stay triggered till it is manually reset after an alarm. This can be very useful if you want to know that there was an attempt to enter in the place which are protected by the radar.

Adjustments
This kit does not need any adjustments, if you follow the building instructions.

Warning
If they are used as part of a larger assembly and any damage is caused, our company bears no responsibility.
While using electrical parts, handle power supply and equipment with great care, following safety standards as described by international specs and regulations.

If it does not work
Check your work for possible dry joints, bridges across adjacent tracks or soldering flux residues that usually cause problems. Check again all the external connections to and from the circuit to see if there is a mistake there.

See that there are no components missing or inserted in the wrong places.
Make sure that all the polarised components have been soldered the right way round. Make sure that the supply has the correct voltage and is connected the right way round to your circuit. Check your project for faulty or damaged components.

If everything checks and your project still fails to work, please contact your retailer and the Smart Kit Service will repair it for you.

Parts
R1 180 KOhm
R2 12 KOhm
R3, 8 47 KOhm
R4 3,9 KOhm
R5, 6, 16 10 KOhm
R7, 10, 12, 14, 17 100 KΩ
R9, 11 1 MOhm
R13, 15 3,3 KOhm
C1, C6 10uF/16V
C2 47uF/16V
C3 4,7 pF
C4, C7 1 nF
C5 10nF
C8, C11 4,7 uF/16V
C9 22uF/16V
C10 100 nF
C12 2,2 uF/16V
C13 3,3nF
C14 47nF
TR1, 2, 3 BC547 , BC548
P1 10 KOhm trimmer
P2 47 KOhm trimmer
IC1, 2 741 OP-AMP
IC3 4093 C-MOS
R TRANSDUCER 40KHz
T TRANSDUCER 40KHz
D1, 2, 3, 4 1N4148

Author:smartkit,Sourced by http://saaqibs.blogspot.com/

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Ultrasonic Distant Obstacle Detector

The first sensor a robot usually gets fitted with is an obstacle detector. It may take three different forms, depending on the type of obstacle you want to detect and also — indeed, above all — on the distance at which you want detection to take place. For close or very close obstacles, reflective IR sensors are most often used, an example of such a project appears elsewhere in this blog. These sensors are however limited to distances of a few mm to ten or so mm at most. Another simple and frequently-encountered solution consists of using antennae-like contact detectors or ‘whiskers’, which are nothing more than longer or shorter pieces of piano wire or something similar operating microswitches.

Circuit diagram:

Ultrasonic Distant Obstacle Detector Circuit Diagram

Detection takes place at a slightly greater distance than with IR sensors, but is still limited to a few cm, as otherwise the whiskers become too long and hinder the robot’s normal movement, as they run the risk of getting caught up in things around it. For obstacles more than a couple of cm away, there is another effective solution, which is to use ultrasound. It’s often tricky to use, as designers think as if they needed to produce a telemeter, when in fact here we’re just looking at detecting the presence or absence of obstacles, not measuring how far away they are. So here we’re suggesting an original approach that makes it possible to reduce the circuit required to a handful of cheap, ordinary components.

Our solution is based on the howlround or feedback effect all too familiar to sound engineers. This effect, which appears as a more or less violent squealing, occurs when a microphone picks up sound from speakers that are connected to it via an amplifier. Feeding back the output signal from the speaker into the input (the microphone) in this way creates an acoustic oscillator. Our detector works on the same principle, except that the microphone is an ultrasound receiver while the speaker is an ultrasonic emitter. They are linked just by a very easily-built ordinary amplifier. Feedback from the output to the input occurs only when the ultrasonic beam is reflected off the obstacle we are trying to detect.

As Figure 1 shows, the receiver RXUS is connected to the input of a high-gain amplifier using transistors T1 and T2. As the gain of this stage is very high, it can be reduced if necessary by pot P1 to avoid its going into oscillation all on its own, even in the absence of an obstacle. The output of this amplifier is connected to the ultrasonic emitter TXUS, therby forming the loop that is liable to oscillate due to the effect of feedback. When this takes place, i.e. when an obstacle is close enough to the ultrasonic transducers, a pseudo-sine wave signal at their resonant frequency of 40 kHz appears at the amplifier output, i.e. at the terminals of the transmitting transducer.

This signal is rectified by D1 and D2 and filtered by C3 and, if its amplitude is high enough, it produces a current in R6 capable of turning transistor T3 on to a greater or lesser extent. Depending on the nature and distance of the obstacle, this process does not necessarily happen in a completely on/off manner, and so the level available at T3 collector may be quite poorly-defined. The Schmitt CMOS invertors are there to convert it into a logic signal worthy of the name. So in the presence of an obstacle, S1 goes high and S2 goes low. Powering can be from any voltage between 5 and 12 V.

The gain, and hence the circuit’s detection sensitivity, does vary a bit with the supply voltage, but in all cases P1 makes it possible to achieve a satisfactory setting. Although it is very simple, under good conditions this circuit is capable of detecting a normally-ultrasound-reflective obstacle up to around 5 or 6 cm away. If a smaller distance is needed, you simply have to reduce the gain by adjusting P1. Building the circuit is straightforward. Both transducers are 40 kHz types that can be found in any retailers, and the other components couldn’t be more ordinary.  in Figure 2.

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Ultrasonic Dog Whistle

Its well known that many animals are particularly sensitive to high-frequency sounds that humans cant hear. Many commercial pest repellers based on this principle are available, most of them operating in the range of 30 to 50 kHz. My aim was, however, to design a slightly different and somewhat more powerful audio frequency/ultrasonic sound generator that could be used to train dogs. Just imagine the possibilities - you could make your pet think twice before barking again in the middle of the night or even subdue hostile dogs (and I guess burglars would love that!).

From what Ive read, dogs and other mammals of similar size behave much differently than insects. They tend to respond best to frequencies between 15 and 25 kHz and the older ones are less susceptible to higher tones. This means that an ordinary pest repeller wont work simply because dogs cant hear it. Therefore, I decided to construct a new circuit (based on the venerable 555, of course) with a variable pitch and a relatively loud 82 dB miniature piezo beeper.

The circuit is very simple and can be easily assembled in half an hour. Most of the components are not really critical, but you should keep in mind that other values will probably change the operating frequency. Potentiometer determines the pitch: higher resistance means lower frequency. Since different dogs react to different frequencies, youll probably have to experiment a bit to get the most out of this tiny circuit. The circuit is shown below:

Circuit diagram

Despite the simplicity of the circuit, there is one little thing. The 10nF (.01) capacitor is critical as it, too, determines the frequency. Most ceramic caps are highly unstable and 20% tolerance is not unusual at all. Higher capacitance means lower frequency and vice-versa. For proper alignment and adjustment, an oscilloscope would be necessary. Since I dont have one, I used Winscope. Although its limited to only 22 kHz, thats just enough to see how this circuit works.

There is no need to etch a PCB for this project, perf board will do. Test the circuit to see how it responds at different frequencies. A 4k7 potentiometer in conjunction with a 10nF (or slightly bigger) capacitor gives some 11 to 22kHz, which should do just fine. Install the circuit in a small plastic box and if you want to, you can add a LED pilot light. Power consumption is very small and a 9V battery should last a long time.

Possible further experimentation: Im working on an amplified version of the whistle to get a louder beep. All attempts so far havent been successful as high frequency performance tends to drop dramatically with the 555. Perhaps I could use a frequency doubler circuit - I just dont know and Ive run out of ideas. One other slightly more advanced project could be a simple "anti-bark" device with a sound-triggered (clap) switch that sets off the ultrasonic buzzer as soon as your dog starts to bark.

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