ultrasonic receiver/transmiter

Hey guys,

I try to design a system in which i use 2 ultrasonic sensors and pic micro-controller. I will like to ask what others circuits it will need to design (filters/transmitter/receiver) and where it is possible to get resources /how to design these circuits???

To make an ultrasonic transmitter and receiver you need no PIC microcontroller. You need e.g. a NE 555 timer, make an ultrasonic generator, and tune it to the frequency printed on the transducer. Some are made for 24 kHz , others for 40 kHz (smaller diameter).
For a receiver, you need an audio amplifier tuned again to the same frequency. You can use an opamp or another audio amplifier, again tuned to 22 or 40 kHz.

Depending on the purpose or how you intend to use the transmitter and receiver, you can use a programmable device to evaluate the receiver output amplitude, pulse delay, etc.

I am looking for the circuits which are able to drive the sensors.

Furthermore i looking for the circuits which can be used. For example can you give me an example for the circuits of the receiver and the transmitter ?

Tom2 said:

I am looking for the circuits which are able to drive the sensors.

Furthermore i looking for the circuits which can be used. For example can you give me an example for the circuits of the receiver and the transmitter ?

Click to expand...

To do this I would need to know the frequency of your transducers. Usually they are made for 24 or 40 kHz.

Then it depends what system you want to create by transmitting and receiving the ultrasound. One application is a reflective sensor or a sensor indicating an obstacle between the transmitter and receiver. Or you want to transmit data by ultrasonic pulses.

Each of similar systems differs in electronics, generated power, etc.

The frequency of the traducers are 40kHZ. I try to create a circuit for ultrasonic anemometer so the the traducers will sends pulses between them.

Thanks in advance.

Tom2 said:

The frequency of the traducers are 40kHZ. I try to create a circuit for ultrasonic anemometer so the the traducers will sends pulses between them.

Thanks in advance.

Click to expand...

OK, so now please teach me how far from each other the transducers should be? I guess the distance allows to indicate air speed with more precision the longer the distance is.

You can choose to measure the delay between the 40 kHz sinusoidal waves; then you will need a circuit which generates an output proportional to the phase delay. Google "digital phase meter" for it.

Or you can transmit ultrasonic pulses, obviously longer than the period of the 40 kHz: T = 1/f = 25 microseconds. And again you can use a similar circuit to determine the phase delay between the pulses, or, you can use a resettable counter which will be clocked to indicate the delay, again proportional to air speed.

It is possible that someone designed such circuitry based on the PIC or Arduino series microcontrolers. Visit their libraries to see how to do it.

Thanks jiripolivka,

But let taking from the begging at first how to design the transmitter of the sensor??How to drive the sensor?
Secondly : Do you mean to use the the digital phase meter circuit as a receiver????

Tom2 said:

Thanks jiripolivka,

But let taking from the begging at first how to design the transmitter of the sensor??How to drive the sensor?
Secondly : Do you mean to use the the digital phase meter circuit as a receiver????

Click to expand...

The drive circuit depends on the distance between both transducers. I used a 40 kHz ultrasonic transmitter and receiver to send commands over a room, distance of 3-5 meters.
The transmitter utilizes a CD4011 connected as a multivibrator (three gates), the fourth gate is an inverter. The transducer is connected from input to output of the inverter, so the voltage across it is ~ 4-5 V p-p. As the transducer is a capacitor, it can be connected directly to the inverter.

The receiver utilized originally a 7414 quad Schmitt trigger, DC -biased at input to amplify the signal from the receiving transducer. A better circuit will be an audio amplifier with an opamp allowing an adjustable gain, and another opamp as a comparator which will generate full-swing TTL output pulses.

At 40 kHz, most low-cost opamps like LM324, 741 or 072 can be used, as well as the audio amplifier, and the comparator.

If my sensors has a distance of 10 cm around how many gates need for the transmitter to drive it.Also why to use gates and not the micro-controller??

For my receiver a opamp for amplification and another one for comparator is enough? Any cross zero detection is not needed ?
Furthermore any filter is not needed???

Tom2 said:

If my sensors has a distance of 10 cm around how many gates need for the transmitter to drive it.Also why to use gates and not the micro-controller??

For my receiver a opamp for amplification and another one for comparator is enough? Any cross zero detection is not needed ?
Furthermore any filter is not needed???

Click to expand...

I described what I used. For a distance of ~10 cm, the propagation loss will be low, so you can possibly operate without a high-gain audio amplifier. If you prefer using a micro-controller, try it.

The zero-crossing detector can be used, too. As both transducers operate at 40 kHz, you can possibly use no filter in your circuit.

Try to look in the edaboard archive; I remember seeing parking radar with ultrasonic transducers, one circuit used TTL ICs, another, Arduino.

this link might help u
**broken link removed**

it was my project. it worked for me about 200 feet range and also give the degree.
i have my thesis and hardware also...
you have to design transmitter by means of 555 timer and reciever in three steps..
equalization and some more..