Hi All who can help me? i am trying to drive a Piezoelectric Transducer , but there are 2 question. first, in many document i read,mentioned that for driving this transducer and for getting 120 watts power, we have to use high voltages about 400 volt,and my question is how we can use 400 volts for radiation resistance about 20 ohms??i thing one thing is wrong here,what is wrong???? 2nd, in these documents mentioned that the frequency is changing because of changing impedance,is it necessary to use a frequency control circuit or we can drive the transducer without using this circuits??? please help me
Amigo do u know what is consideration for driving this transducer? i found ou that we need to use a transformer after power amplifier and in last step for increasing voltage and isolation. acctually i wanna produce a pulse signal by AVR and then use that for driving transducer, but i dont know what i need for doing this work can u help me , plz?
It shows you how to wind the transformer for achieving this application then apply the coding that you would in a pic micro to atmel cpu or in your case what you call the arduino Its All roughly the same thing
So you want pwm out one channel driving one of the fets and inverted on the other output driving the other Fet for a signal frequencey of 42khz to 47khz depending on what ever your piezo element is rated at
Lets see how you would work this out If you know your instruction time then one port will be high for x cycles instruction time and the other port pin will be low during that period
To complete one cycle the you would have to use period = 1/f which is 1/ 42000
So lets see period for 42khz is 23.81us which constitutes one cycle 11.9 us On 11.9us OFF
You would use possibly a timer interupt and then invert the state of the ports every 11.9us
Preloading the timer with a value so that every 11.9us it overflows and calls the on interrupt routine
The on interrupt routine would simply alter the state of the ports ie if Invert port pin state ie low to high or high to low
i.e Port.pin = NOT (port.pin ) // invert state
C syntax would be something like this
Inside your interrupt call back PORTD = PORTD ^ B00100100; // invert bit 5 , 3 (digital pin 5, digital pin 4), leave others untouched
Or not having worked with ardiuno reading through it appears you may do this ISR(TIMER1_COMPA_vect) { digitalWrite(PORTPINA, !digitalRead(PORTPINA)); digitalWrite(PORTPINB, !digitalRead(PORTPINB)); }
Thats how I would approach this Then if you need to check your output with a simulator or a Scope
You would have to alter the value in the timer to account for other instyruction times to get far greater accuracy on your final frequency out
You are using a form of pwm by changing the pin sates with the use of a timer interrupt although not true pwm it is essentially a square wave oscillator with two pins You could use real pwm to ensure correct V out stabilized if you were using adc to check output voltage sampled from your secondary of the TX but you don’t really need to be that accurate Your frequency out how ever does need to be reasonably accurate so that it lies within the tolerance of your Piezo transducers that is 42khz to 47khz
There is nothing to stop you using for example a 555 timer IC Or a Cmos oscillator with nand gate attached to the output to give you inverted and non inverted drives to the fets although you do need to observe your drive voltage to the gates of the Fets typically this shouldnt exceed 5 volts for given fets
thx ur helps is usefull but in the web links that u put,( http://www.picproje.org/index.php?topic=45268.0 )(turkish) i thing one thing is wrong, because in that circuit, he use transfirmer in last step an after amplifying,and in this situation if we want to have 120 watt power ,in output we have to have 50 volts voltage and 2.5 amps current and actually in primary stage of transformer by turns (12/50) then we have to have 2.5*4=10 amps current,isnt it???or i think wrong???
Cant see how you calculated your current though dont forget the primary acts as open circuit at 42 khz so current I would have thought would be about 0.75 amp or so for 50 watts in secondary at 67.5 volts
so if i wanna have 120 watt in secondary(output) and input of transducer,how much voltage need current i need in secondary??????? why primary act as open circuit????? can i use IRFZ840 istead of two transistors(MOSFETs)??? ty again
I calculate 1.75 amp which means halve the gauge on the secondary winding looking at the data sheet cant see why not IRF 840 should be ok Id = 8 amps and max vgs = +- 20 volts you are only using 5 volts gate drive which gives 3 amps max Ids acc the graph
Someone else might have a far better answer to this but thats what i would do
Only one way to find out I suppose Try it and see I'd be interested to see how close my answers are last time round i did this It worked out A ok
Im sure there are many other points that you would have to take into account like the type of core etc but for these purposes I think It may just work You may have to take one or two turns off or on thats to get resonant frequency correct but to all intensive purposes It will work ( thats what matters at the end of the day Does it work or not )
dear Mark i have a question i saw that in some made circuits , some producer use PWM controlling for controlling frequency because of chnaging frequency during running, do you know do i have to use frequency controlling for driving algae removal circuits or this technique is optional and is not necessary??? do you have any information about Lp-Bs(Low Power Bright Signal) Technolgy??does it electronical technique or Mechanical type?? how can i use this technique for my circuits? can i use this circuits as my driver?(attached file) thanks mi mejor amigo
The discussion addresses driving a 120W piezoelectric transducer, focusing on the required high voltage (~400V) and the apparent discrepancy with the radiation resistance (~20 ohms). It clarifies that achieving 120W output involves high voltage and current levels, typically requiring a transformer after the power amplifier stage for voltage step-up and isolation. Calculations suggest secondary voltages around 65-68V with currents near 1.75-2.5A to deliver the desired power, while the primary side current depends on transformer turns ratio and wire gauge. The primary winding behaves almost like an open circuit at ultrasonic frequencies (~42kHz), reducing current draw. Driving the transducer commonly uses a PWM or square wave oscillator at the transducer's resonant frequency (42-47kHz), with frequency accuracy important to maintain resonance and efficiency. Frequency control circuits or timer interrupts can be used to generate the drive signal, but strict frequency control is not always mandatory. MOSFETs such as the IRFZ840 are suitable for switching, provided gate drive voltages are within specifications. Wire gauge selection for transformer windings is critical to handle the required currents. Additional questions concern the necessity of frequency control for applications like algae removal and the nature of Low Power Bright Signal (Lp-Bs) technology, with no definitive answers provided. Reference materials and example circuits were shared to assist in transformer winding and drive signal generation. Summary generated by the language model.
