I breadboarded a circuit using a TDA7052A to feed a 0.5W 8 ohm speaker. I wired it up exactly the way it was in a book I'm reading, which is very similar to the way the datasheet shows to wire it up. Only difference is I used a different sized filter capacitor for the power supply. I am getting no sound out of the speaker. I've checked the audio signal coming straight out of my phone with my oscope, right after the pot, right after the coupling cap and at the outputs of the chip. The signal is very clean at all input points, but there is a dc offset taking place after the coupling cap of 2.7 volts. The signal at the outputs of the chip is a different story. I used the math function to look at the difference between the two outputs and they are both ac signals, even when there is no input audio signal. In fact, the output signals don't even appear to change when I input audio or not. They are both in phase and have the same amplitude, so the difference is just a dc signal.

The thing is, when I first connected the 6V power I accidentally connected it to one of the outputs of the chip (pin 5). I'm trying to figure out if this fried the chip without having a known good one on hand. Schematics of the internals seem to be vague, or else it's just my lack of knowledge. It looks like there are three amplifiers in the chip. I'm assuming the 6V I applied to the output, which is the output of one of those three amps, caused too high of a current to feed back to its input and destroyed it. I can't find much detail on these chips and how they work. Could anyone with more understanding chime in?

Thanks

 

I wired it up exactly the way it was in a book I'm reading, which

which . . . tells us nothing. Please post the schematic you are using. It should include part values and reference designators for every part. This is going to come down to a discussion of individual parts, and things get very messy very fast without unambiguous identifiers.

Also, information or a link to the book.

Also, photos of your construction. Audio power amplifier IC's - ALL of them going back to the stone age - are weird. They are ultra-picky about power supply decoupling and pc board / wiring layout.

I used the math function to look at the difference between the two outputs and they are both ac signals, even when there is no input audio signal. In fact, the output signals don't even appear to change when I input audio or not. They are both in phase and have the same amplitude, so the difference is just a dc signal.

That sounds wrong, like a wiring error. You don't say what the "ac signal" is, its amplitude, its frequency, etc. But with no input, the two outputs should be DC.

The part is a single-channel audio power amplifier. It achieves greater power into the speaker by driving it with two signals that are 180 degrees out of phase. This is called BTL, for Bridge-Tied Load. Pin 5 should be an amplified version of pin 2. Pin 8 should be thee same amplitude as pin 5, but inverted. the outputs should have a DC offset from GND that is approx. 50% of Vcc. The difference between the output DC voltages should be less than 150 mV.

For anyone else interested in this thread, here is the datasheet:

https://www.nxp.com/docs/en/data-sheet/TDA7052A_AT.pdf

ak

 

The TDA7052A is old and is obsolete since it has not been made for many years.
If you find one it might be fake or defective. Maybe yours is an old fake or defective one.

 

I owe you two for your time haha. I made a rookie mistake and assumed the wrong counting order for the pins. I counted the left side of the IC correctly. That part's easy to remember. But, I continued my counting from the top of the right side instead of the bottom. I've spent too much time tinkering with discrete components and it's been too long since I've messed with ICs.

Thanks a lot for all that info AnalogKid. I'll aim to be more descriptive in the future. Do you know what that input amplifier is? is it just a differential-output amplifier?

 

The input amplifier also has a built in DC volume control.

 

I made a rookie mistake and assumed the wrong counting order for the pins.

When viewed from the top, DIP IC package pins count counter-clockwise around the package. The same is true for surface-mount 4-sided chips.

This is because when viewed from the top, vacuum tube pins count counter-clockwise.

This is because, going back to the 1920's, the standard assembly for vacuum tubes was to mount them on a flat plate, usually part of a 5-sided chassis box. All of the connecting components and wires were on the underside of the mounting plate, where the socket pins are. Thus, vacuum tubes were (and still are) wired when viewed from the bottom, and when viewed from the bottom, the pins counted in a clockwise direction just like the numbers on a clock face. A very early example of the KISS principle.

I'm sure Audioguru was around in the 1920's, so he can confirm this.

ak

 

All my vacuum tubes were round, I never tried a rectangular one.
At age 77 I am still in pretty good shape so I am hoping to still be active at 100.

 

The TDA7052A is old and is obsolete since it has not been made for many years.
If you find one it might be fake or defective. Maybe yours is an old fake or defective one.

Do you have any recommendations for a similar amplifier that is more contemporary?

 

A PAM8403 is a stereo class-D modern amplifier. Powered from 5VDC, its outputs produce low distortion 2.2W into 4 ohm speakers or 1.4W into 8 ohm speakers. Since they are class-D, they do not waste power by getting hot.

The PAM8403 IC is inexpensive locally. Amplifiers made for ebay, AliExpress and Bangood are also inexpensive: