Analysis of ultrasonic distance measurement circuit with integrated transmitter and receiver

XAndxiang

Analysis of ultrasonic distance measurement circuit with integrated transmitter and receiver [Copy link]

 

Hello everyone, I found this ultrasonic ranging circuit with integrated transmitter and receiver on the Internet, but I don't understand how it works. I hope someone who knows can give me some advice.

littleshrimp

This circuit uses transformer B to boost 9V and controls the transducer to send ultrasonic waves through the CSB-OUT transistor.

The transmit signal is clamped by D5 so that the voltage does not exceed the maximum voltage drop of the diode.

The received signal is filtered and amplified and then output from CSB0-IN.

Get the time difference between sending and receiving, and calculate the distance using the speed of sound and air temperature. If the accuracy is not high, the temperature factor can be ignored.

kittom

This is just part of the circuit.

XAndxiang

littleshrimp posted on 2024-3-6 14:24 This circuit uses the transformer B to boost the 9V voltage, and controls the transducer to send ultrasonic waves through the CSB-OUT transistor. The transmitted signal is clamped by D5 to make the voltage...

Hello, thanks for your reply. Won't a short circuit occur when BG1 is turned on? The 9V is directly connected to the ground.

XAndxiang

kittom posted on 2024-3-6 14:29 This is just part of the circuit

Hello, it is all done. The CSB_IN/OUT leads are connected to the microcontroller.

maychang

Moderator littleshirimp has explained it in enough detail.

One more thing to add: The signal sent by the transformer secondary is much stronger than the received signal, which can be 10,000 times or more. The purpose of diode D5 is mainly to form a protection circuit with R3 to protect the base of 9013 from being damaged when 8050 is working.

In the original image, both 9013 and 8050 tubes are marked as BG1, which is a taboo in drawing.

maychang

XAndxiang posted on 2024-3-6 14:30 Hello, thanks for your reply. Will there be a short circuit when BG1 is turned on? 9V is directly connected to the ground.

Take a closer look yourself, you will see that there is a primary winding of transformer B in between the collector of BG1 and the 9V power supply.

XAndxiang

maychang posted on 2024-3-6 14:45 Take a closer look, there is a primary winding of transformer B in between the collector of BG1 and the 9V power supply.

Oh, I understand. I will just treat it as a piece of wire, thank you. Then I can send the received signal to the amplifier through C10 and R8 for amplification and filtering, and then amplify the output.

秦天qintian0303

What is the frequency of your ultrasonic probe?

XAndxiang

Qintianqintian0303 posted on 2024-3-6 16:53 What is the frequency of your ultrasonic probe?

Bought on Taobao, should be 40KHz

XAndxiang

I drew a demo board based on the circuit diagram above and sent it back to try.