![]() Artenz on Cerabyte: One Terabyte Per Square Centimeter.RT on Going To Extremes To Block YouTube Ads.Joshua on Adding Composite Video To The Mattel Aquarius.Andrew on ’s YouTube Channel Goes In The Toilet.Andrew on Adding Composite Video To The Mattel Aquarius.Jenny’s Daily Drivers: Raspberry Pi Desktop 30 Comments Here’s another almost identical ultrasonic mister circuit with an inductor, and no circuit description: The 74HC4046’s high impedance VCO control voltage input makes it particularly attractive so as to not load the transducer. The ubiquitous and inexpensive 74HC4046 phase-locked loop / voltage-controlled oscillator comes to mind. If I were designing this circuit I would use a voltage-controlled oscillator (VCO) whose frequency is automatically adjusted in a feedback loop by the detected transducer’s output amplitude. I’ve seen almost the same or similar circuit many times on the web (see example link below), but I have never seen a full circuit description. Why not just dump the inductor and the 100nF series cap and drive the piezo directly with the MOSFET? You don’t need the inductor to make the 555 a 113 KHz astable multivibrator, a simple RC network will work, and that’s exactly how this circuit does it. But that’s using the specified static capacitance of the piezo transducer, the dynamic capacitance (and other parasitics) are not specified at self resonance, and there’s no datasheet on offer. The Piezo’s capacitance is 1700pF which with the 220uH inductor and 100nF capacitor resonates at 262,449 KHz, not 113 KHz. What is the purpose of the 220uH toroidal inductor? Maybe the inductor is there to increase the peak voltage across the piezo transducer? I don’t think so, the transducer is rated for 5-12V and this circuit is using 15V already. Posted in home hacks, Science Tagged 555, atomizing transducer, cool mist, humidifier, mosfet, piezo, piezo disk, transducer, ultrasonic atomizer Post navigation They’re not picky about where the water comes from, so if you have enough of them, you can dry a load of laundry in a few minutes. ![]() Check out the demo and build video after the break.Ītomizing transducers can do way more than than moisten the air for our comfort. The circuit is designed for atomizing transducers, which have a resonant frequency of 113 KHz - much higher than your average junk box piezo. ![]() You don’t need much more than that and a handful of passives to recreate this cool junk box experiment, but the spec of the piezo disk is quite important. The driving circuit for this DIY mist maker uses a 555 to generate 113 KHz, a trimmer potentiometer to fine-tune it, and a MOSFET to amplify the signal. That energy introduces standing waves that force the water to break apart into a fine mist on the surface of the piezo disk. These work by using high-frequency sound waves to pound the surface of the water with mechanical energy. You could use a second item as a microphone attached to the same metal piece for creating odd sound effects or a primitive plate reverb.Some cool-mist humidifiers work by flinging water at a vaporizer, but our favorite kind uses a piezoelectric transducer. Attaching it to something metal like a washing machine or disposable aluminium roasting tin creates a peculiarly metallic effect. You need to glue or firmly attach it to a large cardboard box or something similar. Using the largest size as a speaker can be achieved by driving it backwards from a standard radio output through an LT700 audio matching transformer available on another listing. The output can go directly into a standard low level microphone input socket on a tape recorder or computer sound card using screened cable. Two can be used at different spots on the wire for a stereo effect. The piezo part of the bare element will crack and degrade if bent, so the usual method is to attach the element to a piece of tin can first before attaching that to the vibration source. ![]() For example a 10 metre long stretched copper wire when plucked produces something very similar to the old star trek "phasers striking hull," noise, that being a similar method to how they created it in the first instance. I've also used these as contact microphones attached to machinery, farm fences in windy conditions or long stretched wires which can result in some very interesting sound effects. If you would like to mix sizes please select MIX option and let me know which you would like via a site message.ĭiameter(mm) Capacitance(nF) Resonant F (kHz) The 20mm unit is approximately 0.4mm thick with the 27 and 35mm units being about 0.5mm, excluding the solder connections and wires. They have wires attached and are often used in equipment where there is a need for a simple beep sounder, often driven direct from a logic output. This is one item of new piezoelectric speaker element available in a pack quantity of 1, 5, or 10 items. ![]()
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