A simple internet search gives a lot of schematics.I already searched for ultrasonic generator circuits but could not find any schematic on the web that we can use as reference for our design.
Hello Brad!
What part of this circuit should I modify?
Power comes through the push-pull arrangement Q1 Q2 C3 C5. You can test it for driving one transducer, however to drive several it is probably best to build a power stage for each transducer. That is, all circuitry from B1 (diode bridge) to R14 R15.
Hi! how about the oscillator circuit from 74hc4046 to irf2110? do I have to build it for each transducer or a single osci is enough? Is my block diagram correct?
View attachment 148082
Hello Brad! Thanks for the prompt reply!
I would like to drive each transducer with a signal that is sweeping around the resonant frequency so that standing waves are avoided. Can you give me some suggestions as to how would I modify the oscillator circuit? Thanks!
An H-bridge can resemble two op amps in bridged configuration. The aim is to switch current to the opposite direction as soon as a zero crossing occurs. That is how to automatically drive at the resonant frequency.
A zero crossing can be detected by tapping the ends of a resistor which is inline with the transducer. An op amp is a suitable detector since its output delivers 'snap' action. The resistor cannot be too high ohm value, or else it hampers current to the transducer. You must then design a switching circuit to provide AC to your transducer.
You can see a simple schematic in my post in the thread linked below. It is two half-bridges. One of them is driven by bias voltage from the resistor. The other half-bridge is driven by the voltage at the node between the first half-bridge.
https://www.edaboard.com/showthread...c-transducer&p=1615523&viewfull=1#post1615523
Is it possible to implement these two feature in my cleanig system:
auto-resonant-seeking
Sweep
It sounds as though you hope there is a circuit which performs a frequency sweep, then settles at the frequency which produces the greatest amplitude from the transducers. I'm not sure I can design a reliable analog circuit. A microcontroller might be a good controller for such a task. However it may be redundant to do the seeking action each time you turn on the cleaning machine. I don't think the frequency will change much between uses.
Or it's probably easier to do by human evaluation. There are various tunable sine-wave generators. You can watch to see which frequency causes your gang of transducers to bubble more (or buzz louder, or clean better) according to your observation.
Below is a simulation of a twin-tee oscillator which is tunable from 30k to 80kHz. The potentiometer was dialed from low to high position as the simulation ran.
View attachment 148342
If you are familiar with the 555 IC, that makes an easily tunable square-wave generator. A flip flop divides by 2 while it produces 50 percent duty cycle. You can filter it so the waveform is sine-like. You must build a circuit which drives your transducers.
The schematic looks more like an experimental setup (e.g. from a last years project) than an industrial ultrasonic generator. They are basically square wave power generators, achieving the sinusoidal current by the transducer resonance or additional LC filters if required.
Efficiency is low due to class AB power stage, operation at 130 kHz probably problematic.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?