Ultrasonic Circuits

This was one of my first designs: it is an ultrasonic parking sonar. Based on an ultrasonic amplifier from an article seen on a 1982 magazine, it was once installed on the rear bumper of my Volvo Station Wagon. It served very well for many years. Connecting it to the reverse gear lights, it switches on automatically and shows you the distance to the nearest obstacle (according to his beam) on a led scale. When the last led lights, a buzzer is also activated telling you to stop immediately.

C ircuit of a new type of remote control switch is described here. This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz is audible to human beings. The sound of frequency above 20 kHz is called ultrasonic sound. The circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit too comprises a mini transmitter and a receiver circuit.

These ultrasonic circuits are all quite old: my notes date them at mid-70s so they don't use ICs. Nevertheless there are several places where an op-amp would possibly simplify things. Despite their age I hope they are of interest: certainly basic principles don't change. This transmitter is designed to work with the next circuit as a remote control transmitter/receiver. It is only a single channel and you could once get multi-channel chips for the whole job. However ultrasonics have fallen out of favour commercially so I think most of these chips are now obsolete.

The sensor is derivated from Mike Gasperi's Almost Ultrasonic Motion Sensor . We added a forth amplifier-stage. The sensor is equipped with the cheapest crystal microphone. For each ear there are two audio-amplifier stages. The signal passes the diode D7. The positive peak charges C3 which is then discharged through R10 (the time constant T=RC=0,470E-6*1E5=0,047 sec). The peak-level is amplified and passed to the RCX through the 4th op-amp. The sensor has to be calibrated at R1. The RCX raw-values: +/-10-90.

This sensor uses the sound generator in the RCX to make a 15kHz audio tone, which is almost ultrasonic. The tone is received with circuitry similar to my Sound sensor. The output of a crystal microphone MIC is amplified and then only the very high frequencies are further amplified (see plot). This signal is enveloped detected with a diode D1 and capacitor C1. The voltage on the capacitor will equal the average volume of high frequency sound the microphone is picking up at any moment.

This is a very interesting 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 circuit the circuits fine balance is disturbed and the alarm is triggered. The circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm.

This sensor uses the sound generator in the RCX to make a 15kHz audio tone, which is almost ultrasonic. The tone is received with circuitry similar to my Sound sensor. The output of a crystal microphone MIC is amplified and then only the very high frequencies are further amplified (see plot). This signal is enveloped detected with a diode D1 and capacitor C1. The voltage on the capacitor will equal the average volume of high frequency sound the microphone is picking up at any moment.

This is a very basic infrared detector/emitter circuit. One major downside of this circuit, is that ambient infrared light will interfere with its detecting obstacles.

These ultrasonic circuits are all quite old: my notes date them at mid-70s so they don't use ICs. Nevertheless there are several places where an op-amp would possibly simplify things. Despite their age I hope they are of interest: certainly basic principles don't change.

Use this circuit to test if the light coming from your 40khz IR emitter is really emitting the right frequency. The schematic says to use a GP1U5X ir module, but probably any 40khz detector module will work.. I used a GP1U26X module.

This is a very interesting 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 circuit the circuits fine balance is disturbed and the alarm is triggered. The circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm.

You face a serious problem in using a slow ADC with a fast peak detector. The circuit in Figure 1 allows a slow ADC to measure a fast, sampled signal peak. The 100-MHz peak detector for ultrasonic-pulse sampling uses a fast MAX4231 amplifier from Maxim (www.maxim-ic.com). This amplifier has a shutdown feature that facilitates power savings without losing the sampled information. When the circuit samples a peak with a low-TTL-control input, the output of the peak-detector amplifier shuts off, and the output amplifier switches on to measure the output signal.

On these pages, I will introduce the Ultrasonic Range Meter with PIC16F873. As for the range meter which doesn't use PIC, refer to "Ultrasonic Range Meter". I created the PCB pattern for this circuit using EAGLE CAD.

In this example, a BrainStem GP 1.0 microcontroller uses a SRF04 Ultrasonic Range Finder to measures distances to obstacles. The BrainStem GP 1.0 tells the sonar module to emit a "ping" and measure the time it takes to receive an echo. It reveals the distance as a raw time in increments of the timer's resolution which is 1.6 uSec. This example shows a Palm Pilot running the Console to display the sonar readings but any supported Platform could be used.

This is an image Schematic. No Description available.

This is the electronic schematic of the homebuilt SONAR. Only one piezoelectric tranducer is used for both tramsmit & receive. This transducer is switched from TX to RX via the four 4016 switches. A high gain amplifier stage & rectifier translates the received echoes into voltage pulses. The timing is controlled by the PIC12C508 8-pin microcontroller as it is shown in the following figure:

On these pages, I will introduce the Ultrasonic Range Meter with PIC16F873. As for the range meter which doesn't use PIC, refer to "Ultrasonic Range Meter". I created the PCB pattern for this circuit using EAGLE CAD.

An ultrasonic, or sonar, range finder is a common sensor in robotic systems and industrial environments. Even home and automotive uses are possible. A novel sensor design consists of a WC, a few peripheral components, and a pair of ultrasonic transducers (Figure 1). The range-finder module consists of a WC, a transmitter, a receiver, a direct-receive inhibit circuit, and an RS-485 interface. The module's usable range is approximately 4 in. to 16 ft with an accuracy of approximately ±2 in. This performance is sufficient for many industrial, automotive, and robotic uses.

This is a very interesting 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 circuit the circuits fine balance is disturbed and the alarm is triggered. The 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 circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit comprises of a mini transmitter and a receiver circuit. Transmitter generates ultrasonic sound and the receiver senses ultrasonic sound from the transmitter and switches on a relay.