The datasheet for the TC4428A says that the logic inputs maximum voltage is the supply voltage plus 0.3V.
If the 555 is powered from +12V then its max output voltage is +10.7V then nothing burns. The LM7805 is not needed.
The TC4428A has opposite polarity outputs that connect to the piezos. TC2844A output a can connect to the piezos + or to the piezos - and it does not matter. But the piezos must all have the same polarity because they are speakers that must all be in phase.

Audioguru good morning unfortunately a small mishap arose, I just got back from the electronics store and they didn't have the battery and neither did the TC4428A. So I think I'll give the circuit for now with the l293d, then as soon as I get the tc4428a I'll replace it. So you attach the diagram of how it should be with the l293d can you tell me if it's ok? Then I can't find the Li-on battery, is a lead-acid battery still fine, still 12V? Then third question they gave me a stereo cable to connect my mp3 to the circuit, as the audio connector of the circuit is mono, nothing happens??

 

With one wire of each piezo transducer grounded, the old L293 has an output voltage swing of only 10V when its supply is 12V. It is probably too slow to produce narrow 40kHz pulses. Then it will produce low levels and severe distortion. The 555 and logic supply for the L293 must be powered from a 5V regulator.

The TC4428A produces an output voltage swing of almost 24V when its supply is 12V. Then it will be much louder than the L293 and have low distortion.
The L293 output will have DC pulses and the TC4428A will have AC pulses. The piezo transducers might work best with AC.

Stereo or mono? This ultrasonic contraption modulated with PWM will sound awful but might demo that voices can be played.
Do not short the stereo channels together which might destroy your MP3 player, you need a stereo to mono converter circuit for it. Try using only one channel to test this ultrasonic thing.

 

That "stereo to mono converter" can be a pair of 1K ohm resistors, one from each channel, feeding the top of a 1K potentiometer adjusting the output into the mono input to the PA amplifier. I have used that successfully with laptop computers feeding audio to a mono sound system, through the microphone input. The volume control may not be needed if the source is not intended to feed headphones.
Using a 1000 ohm resistor from each channel provides 2K of isolation between the two outputs, which should be adequate for all applications.

 

With one wire of each piezo transducer grounded, the old L293 has an output voltage swing of only 10V when its supply is 12V. It is probably too slow to produce narrow 40kHz pulses. Then it will produce low levels and severe distortion. The 555 and logic supply for the L293 must be powered from a 5V regulator.

The TC4428A produces an output voltage swing of almost 24V when its supply is 12V. Then it will be much louder than the L293 and have low distortion.
The L293 output will have DC pulses and the TC4428A will have AC pulses. The piezo transducers might work best with AC.

Stereo or mono? This ultrasonic contraption modulated with PWM will sound awful but might demo that voices can be played.
Do not short the stereo channels together which might destroy your MP3 player, you need a stereo to mono converter circuit for it. Try using only one channel to test this ultrasonic thing.

No but I went to the electronics store, I went but they didn't have the tc4428a which arrives in a month, so to buffer I want to use the l293d but only for this month. So unfortunately I know that the l293d is obsolete but I only need it for a short time so from my drawing I think I made a mistake because since I have to connect 20 piezos, I don't want to connect them all to output 3 because maybe they are too many so I divide them, and then I put 10 to output 3 and the negative of the piezos to gnd and then I connect the other 10 to output 1 of the other full bridge. Because if I connect them to output 3 and 4 they produce nothing, or I connect them to enable 3.4. However you draw the drawing, you tell me how to connect all 20 of them

 

That "stereo to mono converter" can be a pair of 1K ohm resistors, one from each channel, feeding the top of a 1K potentiometer adjusting the output into the mono input to the PA amplifier. I have used that successfully with laptop computers feeding audio to a mono sound system, through the microphone input. The volume control may not be needed if the source is not intended to feed headphones.
Using a 1000 ohm resistor from each channel provides 2K of isolation between the two outputs, which should be adequate for all applications.

Thank misterbill2 i maybe Will use your solutions because i have all components, for the battery, the lead-acid battery 12V gel its good like Li-on?

 

The L293 has 4 channels. You can have 10 Piezo transducers on two of the channels or 5 transducers on each of the four channels.
The logic inputs you are using must be connected to the output of the 555 and the Inhibit pin1 and pin9 of the L293 must be at +5V for the L293 to do anything.
Many kinds of batteries can produce 12VDC.

 

The L293 has 4 channels. You can have 10 Piezo transducers on two of the channels or 5 transducers on each of the four channels.
The logic inputs you are using must be connected to the output of the 555 and the Inhibit pin1 and pin9 of the L293 must be at +5V for the L293 to do anything.
Many kinds of batteries can produce 12VDC.

ok maybe the configuration of 5 pieces for each channel would be better, so I connect the enable them to 5v as the Vlogic pin, also because I would have connected them to GND. ok better so that you corrected me. then as regards the battery since today at the shop they had nothing and they made me, but at least the tc4428a will arrive in a month. so last question can I insert a 12V and 2A lead gel battery? because the lead battery is easier to find, you tell me

 

I use lightweight Lithium-Polymer and Ni-MH rechargeable batteries that are available in many stores here. My car carries around a heavy lead-acid battery to produce up to 600A to start the engine when it is cold.

 

Uso batterie leggere Lithium-Polymer e Ni-MH ricaricaricabili che sono disponibili in molti negozi qui. La mia auto porta intorno a una pesante batteria acido piombo per produrre fino a 600A per avviare il motore quando fa freddo.

no unfortunately in my area they don't have those batteries not even the Lipo, LiFe or NiMh, they only have the 12v and 2 ah gel lead acid from yuasa, rs pro or other brands, unfortunately I have to take that one, maybe then in a few months I order Li-on or LiFe from the internet, but are lead acid ok for now?

 

A 12V/2Ah gel cell lead-acid battery will be fine if you have a charger for it.
Cell phones, tablets, laptops, radio controlled model airplanes and model cars use LiPO batteries.
I have many solar garden lights that use Ni-MH cells. I have never seen or used a gel cell lead-acid battery.

 

Una batteria di acido di cellule di 12V/2Ah andrà bene se avete un caricabatterie per esso.
I cellulari, i tablet, i portatili, gli aerei modello radiocontrollato e le auto modello utilizzano batterie LiPO.
Ho molte luci del giardino solare che usano le cellule Ni-MH. Non ho mai visto o usato una batteria di acido di cellule di base.

yes yes the charger is included in the package, then in a few months I will buy the Li-on from the internet

 

Gel cells are OK for 12 volt power, but it is important to use the proper charging sequence, which is different from NiCad, Lithium, or NimH cells. So whatever kind you use, it must be charged correctly. Plus gel cells are heavier and so a burden for portable equipment.
But if the system created does not need to be portable, why not consider a mains powered supply? Less expensive in the long term, also smaller and lighter.

 

Le cellule di Gel sono OK per 12 volt, ma è importante utilizzare la sequenza di ricarica adeguata, che è diversa dalle cellule NiCad, Lithium o NimH. Quindi, qualunque tipo che si usa, deve essere addebitato correttamente. Più le cellule di gel sono più pesanti e quindi un fardello per le attrezzature portatili.
Ma se il sistema creato non deve essere portatile, perché non considerare una fornitura di main alimentata? Meno costoso a lungo termine, anche più piccolo e più leggero.

No no the circuit is portabile