I am working on a school project which consists of converting audio signal into amplified pwm signal with a tda amplifier (raw) not a complete circuit with resistors and capacitors, then converting the pwm pulse to 100% of the power supply voltage, and then interpreted as light with a 24v led strip, allowed transistors are MOSFETs and TDA amplifiers for that convert, obtaining the pwm signal only in the anode(+) of the led, and using the negative as gnd(ground).
The problems doing the basic circuit with TDA2050, IRFZ44N:
- The wave becomes inverted, why? because the irfz44n reads the positive signal and then releases the negative drain, based on the positive input voltage of the gate in the range of 0v to 10v maximum.
HERE the normal wave (not inverted)
HERE the wave (inverted)
HERE a pwm normal signal
This problem affects not only the wave, it also affects the pwm output, which will be inverted.
- The pwm signal will go out on the cathode instead of the anode, causing the project to fail.
Now the solution that I formulated to make the pwm output be in the anode (positive) instead of the cathode (negative), consists of using TDA2050, IRFZ44N and L7805CV and irf9540n, here is the circuit:
Explanation: the signal from the left channel enters and reaches the TDA amplifier, the positive on pin 1 and gnd on pin 3, then 24v 1A is fed on pin 5 as positive and on 3 as gnd, then the signal is amplify and become pwm to exit through pin 4 and reach irfz44n through the gate, sharing the gnd in the source, Then the L7805cv feeds the irfz44n with 5v, and then emits the negative pwm signal (drain) to the irf9540n gate, something necessary since the irf9540n has a gate limit of 10v if I'm not wrong, Then, the 5v that power the irfz44n are joined with the 24v in the source of the irf9540n to complete the voltage of the irfz44n (5v) and to be able to drop (drain) of 24v pwm in the anode (positive) of the led strip.
My questions are:
1. Can L7805CV be damaged by joining its positive output voltage (5v) with the positive power supply voltage (24v) as it is mentioned in the picture(5v and 24v join)?
2. Is my circuit at risk of a short circuit?
3. Does my circuit have the risk of damaging the 3.5mm audio input or any device in which I test it with some 24v or 5v overvoltage due to these combinations of mosfets?
4. What suggestions do you give me, in case something else is needed or something is wrong in my circuit?
A small note, I managed to do this only with the tda2050 and the irfz44n, with 5v of voltage, but it was only a test, not something permanent for the aforementioned not works in anode only in cathode and i want to include 4 amps more or 2 that these mosfets and transistors and amplifier allows me...
More explained schematic added: