Ultrasonic generator

Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
Please, i need help to figure out this ultrasonic generator...i need 100V ac, with 100 W...i find this circuit with my attachment which produce 100 V but low power...i need to gain more power..it need to amplify more current right?
 

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ian field

Joined Oct 27, 2012
6,539
Please, i need help to figure out this ultrasonic generator...i need 100V ac, with 100 W...i find this circuit with my attachment which produce 100 V but low power...i need to gain more power..it need to amplify more current right?
The power rating suggests either ultrasonic cleaning or plastic welding.

Its customary to have a current feedback winding in series with the output so arrangements can be made to compensate the load phase angle.

Most transducers are capacitive, but any load is the same as a loss resistance - which throws the vector calculation.
 

AnalogKid

Joined Aug 1, 2013
9,406
Unless I'm missing something, that schematic is for a gain-of-ten inverting amplifier, not a complete ultrasonic generator. What operating frequency do you need?

ak
 

ian field

Joined Oct 27, 2012
6,539
Unless I'm missing something, that schematic is for a gain-of-ten inverting amplifier, not a complete ultrasonic generator. What operating frequency do you need?

ak
When I worked for a firm that made ultrasonic cleaners and plastic welding plant - one particular generator was superficially identical to an audio amplifier.

There was an oscillator guided by a current sensing phase detector at the output.

The most common design was basically a centre-tapped transformer loaded astable. The smallest ran from 55V and had a pair of high voltage transistors. The heavy plant generators had multiple ganged transistors on a tunnel style forced air cooled heatsink.

Many of the cheap commercial units have a self oscillating half-bridge circuit like in CFLs and LV lighting electronic transformers.

In every design I've seen - the output current phase shift is sensed and used to control the oscillator.
 

Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
Unless I'm missing something, that schematic is for a gain-of-ten inverting amplifier, not a complete ultrasonic generator. What operating frequency do you need?

ak
yup..the circuit i post is amplifier..i wonder if after that amplifier,i would like to add more circuit for increasing the power..i want 100 W and frequency range from 20 KHz to 40 KHz
 

Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
When I worked for a firm that made ultrasonic cleaners and plastic welding plant - one particular generator was superficially identical to an audio amplifier.

There was an oscillator guided by a current sensing phase detector at the output.

The most common design was basically a centre-tapped transformer loaded astable. The smallest ran from 55V and had a pair of high voltage transistors. The heavy plant generators had multiple ganged transistors on a tunnel style forced air cooled heatsink.

Many of the cheap commercial units have a self oscillating half-bridge circuit like in CFLs and LV lighting electronic transformers.

In every design I've seen - the output current phase shift is sensed and used to control the oscillator.
yup,i notice that every part of ultasonic generator use transformer...can we find a solution for transformer..i mean i dun want to use transformer,because i want to make portable ultrasonic generator..i want to make with the size of small plastic bottle which smallest as possible..but the power supply also became problem...thanks btw
 

ian field

Joined Oct 27, 2012
6,539
yup..the circuit i post is amplifier..i wonder if after that amplifier,i would like to add more circuit for increasing the power..i want 100 W and frequency range from 20 KHz to 40 KHz
In most power ultrasonic systems; the frequency is determined by the physical dimensions (and resonant frequency) of the transducer - you might get away with a harmonic, but efficiency will be low and it could cook the generator.

EPE & Silicon Chip published an ultrasonic cleaner that became re hashed as a boat hull anti fouling cleaner. their design used a PIC programmed to do frequency hopping - I guess eventually, one of the frequencies hits the sweet spot...............
 

AnalogKid

Joined Aug 1, 2013
9,406
i want to make with the size of small plastic bottle
I don't see how you will get a 100 W power supply plys a 100 W power amplifier in such a small volume, no matter what the shape is. Even with a squarewave output signal and a 90% efficient power supply (which is very high), you still have over 10 W of heat to dissipate somehow.

ak
 

Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
I don't see how you will get a 100 W power supply plys a 100 W power amplifier in such a small volume, no matter what the shape is. Even with a squarewave output signal and a 90% efficient power supply (which is very high), you still have over 10 W of heat to dissipate somehow.

ak
 

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Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
i already made the circuit and can make it to smaller version..but now i want to figure out how to increase the power for my ultrasonic transducer which 100 W..now the output current from my amplifier is 0.025 A...example, i can increase the current to 1 A or 1.5 A with Vrms of 100V then i can get the plus minus 100 W right?or my assumption is wrong?
 

Thread Starter

rizalrazuwan

Joined Sep 5, 2016
7
In most power ultrasonic systems; the frequency is determined by the physical dimensions (and resonant frequency) of the transducer - you might get away with a harmonic, but efficiency will be low and it could cook the generator.

EPE & Silicon Chip published an ultrasonic cleaner that became re hashed as a boat hull anti fouling cleaner. their design used a PIC programmed to do frequency hopping - I guess eventually, one of the frequencies hits the sweet spot...............
i forgot to mention that is my output from my amplifier is plus minus 100V and frequency around 20 KHz to 40 KHz..but the current is 0.025 A..before going to the amplifier circuit..i using pwm from arduino and go to md10C board which get plus minus 12V and frequency which can be adjusted from the arduino coding..

i also found the circuit on web which really good but my country in malaysia and take 2 months to get the product..below is the link

http://www.diytrade.com/china/pd/4979618/PCB_Ultrasonic_Generator.html
 

AnalogKid

Joined Aug 1, 2013
9,406
That is 71 Vrms and 1.77 W. To boost that to 100 W is an increase of over 56x, significant change to your design. Also, if the output is a sinewave then the power dissipation in a class AB power amplifier will be at least 40 W. A class D audio amp will reduce this, but 40 kHz is a pretty high frequency for one of those.

ak
 
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