hello gentlemen I have a simple question, but I can not solve. so considering the l293d driver, if instead of driving DC motors, I control ultrasonic transducers (piezo), where should I connect the PWM signal? I use the single bridge configuration so I only use the right half of the l293d, so I connect the PWM signal to enable 3 and 4, or to the inputs or to all three ?

 

It looks like your Laser Audio circuit we discussed on Stack Exchange is 20 or 30 years old and Does Not Work.

I looked in Google for Ultrasonic Laser Audio and found a modern one (2020) in English called DIY Ultrasonic Audio Laser (You Tube video).
He uses 20 ultrasonic transducers with a part number and uses a microcontroller that modulates the high frequency beam.
The transducers are fed differentially (like I said) with a 36Vp-p signal from a modern driver IC powered from an 18V supply.
The modern driver IC replaces the antique L293 that has voltage losses.

Differential driving is when one driver output and one transducer wire goes positive when the other driver output and transducer wire goes to ground, then on the next ultrasonic cycle they reverse. Then the transducers get an ultrasonic AC voltage that is double the supply voltage.

 

Post your circuit diagram .

 

Here is the defective schematic from the original circuit:

 

It looks like your Laser Audio circuit we discussed on Stack Exchange is 20 or 30 years old and Does Not Work.

I looked in Google for Ultrasonic Laser Audio and found a modern one (2020) in English called DIY Ultrasonic Audio Laser (You Tube video).
Usa 20 trasduttori ultrasonici con un numero parziale e utilizza un microcontrollore che modula il fascio ad alta frequenza.
I trasduttori sono alimentati differenzialmente (come ho detto) con un segnale 36Vp-p da un pilota moderno IC alimentato da una fornitura di 18V.
Il pilota moderno IC sostituisce l'antica L293 che ha perdite di tensione.

La guida differenziale è quando un autista e un filo transducatore va positivo quando l'altro uscita del conducente e il filo transducatore va a terra, poi sul prossimo ciclo ultrasonico si invertono. Poi i trasduttori ottengono una tensione ultrasonica AC che è il doppio della tensione di approvvigionamento.

.but I can do it with the l293d even if it has losses that I can limit do they connect all the inputs to GND? however I understand the concept of connection is a matter of switching on and off the piezos based on the low or high values of the inputs, I was wondering how can I connect 6 transducers, this is what I didn't understand, just because every time you have to reverse them, but I don't understand how, can you draw me a little picture?

 

Here is the defective schematic from the original circuit:

just tell me how to connect the 6 piezos in an inverted way as you said, but I still don't understand, maybe with a drawing I understand.

 

It looks like your Laser Audio circuit we discussed on Stack Exchange is 20 or 30 years old and Does Not Work.

I looked in Google for Ultrasonic Laser Audio and found a modern one (2020) in English called DIY Ultrasonic Audio Laser (You Tube video).
He uses 20 ultrasonic transducers with a part number and uses a microcontroller that modulates the high frequency beam.
The transducers are fed differentially (like I said) with a 36Vp-p signal from a modern driver IC powered from an 18V supply.
The modern driver IC replaces the antique L293 that has voltage losses.

Differential driving is when one driver output and one transducer wire goes positive when the other driver output and transducer wire goes to ground, then on the next ultrasonic cycle they reverse. Then the transducers get an ultrasonic AC voltage that is double the supply voltage.

AudioGuru I think I solved it with greybeard on stack exchange in the last answer where he shows me his redone circuit and in the comments on the answer. So I do this: I don't connect anything to the enable pins but I bring them to gnd, then I take three piezos and I connect them in parallel, then I take the positive terminal of the piezos in parallel and connect it to output 3 and the negative terminal to gnd, and I let the pwm signal enter input 3, I repeat the same operation with the other 3 piezos, and this time connect them to output 4 and input 4. But you talk about differential driving and inversion, and I don't know this concept 'I understand, could you explain it to me very simply or with a drawing? thanks friend

 

The transducers do not switch on and off. Instead they are fed a modulated ultrasonic voltage that needs to appear across them. They are connected to the L293 outputs 3 and 4. But with L293 inputs 3 and 4 fed with the same signal, the transducers get no voltage across them and do nothing.

Instead if you connect one wire of the transducers to ground then they will get a very low signal and work, but with a very small range and not loud enough. The datasheet for the transducers says the max allowed p-p voltage is 150V (!) but the L293 is powered from only 3.7V and its output is only maybe 2.2V p-p if you are lucky.

The newer circuit uses a driver IC that has two rail-to-rail (no voltage loss) outputs and one is already inverted. With an 18V supply, its output to the transducer is 36V p-p.

Here is the modern replacement for the antique L293:

 

Here is a bridged audio amplifier:

 

The transducers do not switch on and off. Instead they are fed a modulated ultrasonic voltage that needs to appear across them. They are connected to the L293 outputs 3 and 4. But with L293 inputs 3 and 4 fed with the same signal, the transducers get no voltage across them and do nothing.

Instead if you connect one wire of the transducers to ground then they will get a very low signal and work, but with a very small range and not loud enough. The datasheet for the transducers says the max allowed p-p voltage is 150V (!) but the L293 is powered from only 3.7V and its output is only maybe 2.2V p-p if you are lucky.

The newer circuit uses a driver IC that has two rail-to-rail (no voltage loss) outputs and one is already inverted. With an 18V supply, its output to the transducer is 36V p-p.

Here is the modern replacement for the antique L293:

ok I don't know this, so I have to replace the l2932 so could you tell me the connections of the piezos with this ic maybe sending me the diagram with circuitlab

 

Here is a bridged audio amplifier:

ok yes yes so is the bridge amplifier contained in the tc44288a?

 

The transducers do not switch on and off. Instead they are fed a modulated ultrasonic voltage that needs to appear across them. They are connected to the L293 outputs 3 and 4. But with L293 inputs 3 and 4 fed with the same signal, the transducers get no voltage across them and do nothing.

Instead if you connect one wire of the transducers to ground then they will get a very low signal and work, but with a very small range and not loud enough. The datasheet for the transducers says the max allowed p-p voltage is 150V (!) but the L293 is powered from only 3.7V and its output is only maybe 2.2V p-p if you are lucky.

The newer circuit uses a driver IC that has two rail-to-rail (no voltage loss) outputs and one is already inverted. With an 18V supply, its output to the transducer is 36V p-p.

Here is the modern replacement for the antique L293:

so I always do the pwm modulation with the 555, and then as a driver I use the tc4428a instead of the l293d, right? send me the connections with the 6 piezos so I can build it

 

1) Use a 12VDC 100mA or more supply. 18VDC is the absolute maximum.
2) Connect both inputs of the TC4428A to the output of the 555.
3) Connect one wire of each transducer to TC4428A output #1 and connect the other wire of each transducer to the other output of the TC4428A.

The transducers must all be connected with the same phase.

 

1) Use a 12VDC 100mA or more supply. 18VDC is the absolute maximum.
2) Connect both inputs of the TC4428A to the output of the 555.
3) Connect one wire of each transducer to TC4428A output #1 and connect the other wire of each transducer to the other output of the TC4428A.

The transducers must all be connected with the same phase.

hello Audioguru so i made a little drawing of the circuit diagram. The battery I have chosen is a 12 V 500 mA, is it ok? and then I connected the piezos in parallel as you saw in the drawing, you told me to connect them in phase but how should I do it? Also where do I connect the two NC pins of the tc44288a?

 

1) Use a 12VDC 100mA or more supply. 18VDC is the absolute maximum.
2) Connect both inputs of the TC4428A to the output of the 555.
3) Connect one wire of each transducer to TC4428A output #1 and connect the other wire of each transducer to the other output of the TC4428A.

The transducers must all be connected with the same phase.

also in the video you talked about, the 2020 youtube laser audio ultrasound one, that guy inserted an LM358 operational amplifier into the circuit, do I have to insert it too?

 

hello Audioguru so i made a little drawing of the circuit diagram. The battery I have chosen is a 12 V 500 mA, is it ok? and then I connected the piezos in parallel as you saw in the drawing, you told me to connect them in phase but how should I do it? Also where do I connect the two NC pins of the tc44288a?View attachment 284181

You don't connect the NC pins to anything.

 

Put a 100uF electrolytic capacitor and a 0.1uF ceramic capacitor (marked 104) parallel with the 12VDC close to the ICs.
Connect the transducers in phase as I show them in post #13.

Most Chinese online places have the TCT40-16T transducers but Amazon does not have anymore and might not get more.
The modern video shows them at AliExpress.

Why do you have a 7805 5V regulator? The datasheet for a 555 shows that it works fine from 12V up to 16V.
How will you adjust the frequency of the 555 to the 40kHz peak of the transducers?

 

Put a 100uF electrolytic capacitor and a 0.1uF ceramic capacitor (marked 104) parallel with the 12VDC close to the ICs.
Connect the transducers in phase as I show them in post #13.

Most Chinese online places have the TCT40-16T transducers but Amazon does not have anymore and might not get more.
The modern video shows them at AliExpress.

Why do you have a 7805 5V regulator? The datasheet for a 555 shows that it works fine from 12V up to 16V.
How will you adjust the frequency of the 555 to the 40kHz peak of the transducers?

then I have to insert the two capacitors you mentioned in parallel where, I'll make you a drawing, for the piezos I'll buy them on an Italian site that have up to 40 v input voltage for the regulator I can also change and get another one, too as regards the regulation of 40 KHz, you tell me, also because the guy on youtube inserted an lm358, do I have to do it too? tell me all the components
https://www.futurashop.it/robotica/sensori-2/ultrasuoni/capsula-trasmittente-ultrasuoni-5340-tx40

 

Put a 100uF electrolytic capacitor and a 0.1uF ceramic capacitor (marked 104) parallel with the 12VDC close to the ICs.
Connect the transducers in phase as I show them in post #13.

Most Chinese online places have the TCT40-16T transducers but Amazon does not have anymore and might not get more.
The modern video shows them at AliExpress.

Why do you have a 7805 5V regulator? The datasheet for a 555 shows that it works fine from 12V up to 16V.
How will you adjust the frequency of the 555 to the 40kHz peak of the transducers?

from this addition in red to my drawing the capacitors should be added in parallel between the positive and negative terminals of the battery and the tc44288a, as i drew?

 

Connect the two capacitors between +12VDC and 0V (circuit ground) near the ICs.

You do not need a 5V regulator. The ICs work perfectly from 12VDC.
The guy in the video you found used the 5V regulator because it was used in the ultrasonic distance measuring module he took the transducers from, <Mod: Offending text deleted>

You will need a preamp IC (something better than a lousy old LM358) if the output sound and distance are not loud enough.
It might work fine from a cell phone driving the 555 modulation input but a microphone will need a microphone preamp circuit.

I see no technical details for the transducers from Futurashop. Post their PDF datasheet file.

future shop piezos have a max input voltage of 40 V and an input current between 10 and 15 mA. if you need to change them tell me. also the capacitors can I take them both ceramic? because it is easier for me to find them, also which preamp IC should I take and how to connect it? one last question, but connecting the piezos in phase means connecting them in parallel right? furthermore the 555 receives audio from a smartphone through a 3.5 mono connector