When we hear the word “Ultrasonic” we often refer it to bats and dolphins communication. Technically, “Ultrasonic” applies to sound that is anything above the frequencies of audible sound, and includes anything over 20kHz. Frequencies used for medical diagnostic ultrasound scans extend to 10 MHz and beyond. This dog repellent ultrasonic circuit will chase away angry dogs. It comprises of a 555 timer IC, a speaker/piezoelectric and a little ferrite transformer.
The main part of this circuit is a 555 timer IC. A 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. You can use the 555 effectively without understanding the function of each pin in detail. Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. The 555 can source or sink 200 mA of output current, and is capable of driving wide range of output devices.
To use this circuit adjust 4k7Ω Resistor at resonance frequency of the piezo transducer for maximum amplitude of the repeller ultrasonic sound. At 11 KHz to 22kHz this can reach a value of 10Vpp and the buzzer is a passive one (without generator).
Note: Ultrasonic frequency must be set with a dog nearby.
NC Push Button
Dog Repellent Ultrasonic Circuit 2 – [Link]
This circuit is built to repel mosquito using high frequency sound. The design is comprised of LM555 timer which provides the pulse generation and precision timing. It is also a stable controller capable of monostable or astable operation. The 74HCT4017BQ device is a Johnson decade counter with 10 decoded outputs. It provides the signal to be fed into the 555 timer which is connected to the output piezo speaker. The piezo speaker generates the sound. The Bipolar Junction Transistors(BJT) BC337 and BC327 acts as the amplifier of the output sound. It forms the push-pull amplifier that is more efficient than a single-ended Class A amplifier.
Electronic Mosquito Repeller – [Link]
While trying to create a circuit that detects whether water is flowing through a pipe by measuring the vibration with a piezoelectric sensor, just to see what happens I taped the sensor around my finger and – to my surprise – got values that were a very noise-free representation of my heart rate!
Measuring Heart Rate With A Piezo – [Link]
by Joonas Pihlajamaa @ codeandlife.com:
Today’s post is something I’ve prepared for a long time. Hardware-wise it’s a simple thing – ATtiny45 emulating a PS/2 device, sending a keypress when three knocks are detected in the attached piezoelectric sensor (or piezo buzzer as they are also called). But if your computer can boot on PS/2 keyboard input and you have your computer stowed somewhere hard to reach (or just want to impress your friends), it’s a pretty neat little gadget! Here’s a video of it in action:
Turning PC On with a Knock using ATtiny45 – [Link]
by Stephen Evanczuk @ digikey.com:
Pulse-energy-harvesting applications convert bursts of energy to sufficient power for operating simple circuits such as wireless switches, wireless data loggers, remote controls, and the like. To build these designs, engineers can draw on a wide variety of available ultra-low-power ICs and energy transducers from manufacturers including EnOcean, Linear Technology, Linx Technologies, Maxim Integrated, Measurement Specialties, Microchip Technology, Mide Technology, ROHM Semiconductor, Schurter, Silicon Labs, and Texas Instruments, among others.
Powering Circuits through Pulse-Energy Harvesting – [Link]
Researchers at Columbia Engineering and the Georgia Institute of Technology have reportedly made the first experimental observation of piezoelectricity and the piezotronic effect in an atomically thin material, molybdenum disulfide (MoS2). The piezo effect is traditionally thought of as one property of hard crystalline quartz. Using this new material it would now be possible to manufacture electric generator and mechanosensation devices that are optically transparent, extremely light, flexible and elastic.
Atomically thin Piezo Material – [Link]
80 dB acoustic signal at only 3V power supply and a really miniature size place this new component into a top class.
Belgian company Sonitron and its top-level products ar probably familiar to you from our articles and from our offer in this segment. We continue in increasing of standard stock types and this time we have here an extraordinary interesting type – SMA-13LV, interesting mainly for low-voltage applications. Series of buzzers marked as “SMA” is known by its variousness, as we find here types with loudness of 75-98 dB, THT and SMT vesions, and versions with a stable, as well as intermittent signal. Various izes from 13 to 30 mm with a pitch of 7.5 to 20.32 mm enable to select the right type for a given application. In general, bigger types provide a more loud signal, but it depends on a concrete type. This series is suitable for general use – everywhere, where a reliable buzzer is necessary, including industrial conditions.
For a succesfull use, it´s only necessary to connect a suitable supply voltage – usually in extremely wide range (for example 1.5-15V). Usually, on the upper end of a supply voltage range we get the highest loudness and at lower voltages we receive a higher lifetime.
Very similar is also the SMAT series (transducers), which in contrast to the SMA series doesn´t contain a driver, that´s why it needs an extenal electronics.
For really tough conditions, the Sonitron SAP. series is suitable. These are buzzers for various usage in traffic, for example as a reverse movement indicator (danger of close approximation). They excell in extreme rigidity, what make them widely used even in avionics, miltary and trucks. SAP series has a specifi usage, that´s why we keep these types as items upúon request.
Another novelties in our standard stock offer can be found below this article. Detailed information can be found in datasheets at particular types and in the new Sonitron 2014 catalogue.
Piezo buzzer Sonitron SMA-13LV deploys maximum from a minimum – [Link]
Shabaz over at Element14 writes:
This post is about an interesting, low-cost sensor that doesn’t need much processing to use, and has some unique characteristics – a PVDF (polyvinylidene difluoride) Piezoelectric sensor. The sensors looks like a small strip of plastic, and can be used for detecting movement or vibrations even into ultrasound. Such devices can help sense in many practical, real-world scenarios. They are extremely sensitive, low cost and easy to use. Some simple practical experiments with these sensors are described, finally looking at detecting ultrasound.
Impact, vibration and ultrasound sensing with PVDF Piezo sensors – [Link]
Researchers Steve Dunn at Queen Mary University and James Durrant at Imperial College London have been experimenting with a new design of thin, flexible solar cell made from zinc oxide. Manufacturing costs of the new cells will be significantly lower than conventional silicon based technology. The only disadvantage is their poor efficiency; just 1.2 %, a fraction of that achievable with silicon.
The material also exhibits piezo-electric properties, nanoscale rods of the material generate electricity when they are subjected to mechanical stresses produced by sound wave pressure. Sound levels as low as 75dB, equivalent to that from an office printer, were shown to improve efficiency. Durrant said “The key for us was that certain frequencies increased the solar cell output, we tried our initial tests with various types of music including pop, rock and classical”. Rock and pop were found to be the most effective. Using a signal generator to produce sounds similar to ambient noise they saw a 50 % increase in efficiency, rising from 1.2 % without sound to 1.8 % with sound.
New Solar Cell Shows a Preference for AC/DC – [Link]
by Publitek European Editors
There are many different types of accelerometers for industrial applications, ranging from the latest micro-machined capacitive devices to traditional rugged piezo electric crystals. The boom in portable devices and the advantages of knowing the position and orientation of the equipment, as well as the increased use of accelerometers in vehicle air bags, has led to an explosion in the different types of devices in recent years. All of this is to the advantage of the engineer who can use the wide range of devices for different applications, from monitoring to position measurement.
Sensor Technologies for Accelerometers – [Link]