Convert TDA2030 Amplifier Module Push/Pull Output to "Class A"

dendad

Joined Feb 20, 2016
3,323
The amplitude of the swing will still be from 0V to +Vcc, less a bit.
The resistance the amp can drive is determined by its design. The load resistance needs to be enough to limit the current to the amp's max allowable current. Extra turns on the coil can increase the magnetic field.
You cannot get the coil current to be zero at rest and still produce a unidirectional coil current for both +Ve and -Ve going signals unless you run the coil via the capacitor and a bridge rectifier. Then, the coil current will be full wave rectified but will not produce a magnetic field accurately echoing the input signal.
Maybe some more info on what you are actually trying to accomplish would help.
Some indication of why the current needs to be unidirectional???
What is the end application of all this?
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
44
The amplitude of the swing will still be from 0V to +Vcc, less a bit.
The resistance the amp can drive is determined by its design. The load resistance needs to be enough to limit the current to the amp's max allowable current. Extra turns on the coil can increase the magnetic field.
You cannot get the coil current to be zero at rest and still produce a unidirectional coil current for both +Ve and -Ve going signals unless you run the coil via the capacitor and a bridge rectifier. Then, the coil current will be full wave rectified but will not produce a magnetic field accurately echoing the input signal.
Maybe some more info on what you are actually trying to accomplish would help.
Some indication of why the current needs to be unidirectional???
What is the end application of all this?
I am a bit confused since audioguru said removing the cap would cause the amp to run hot. I assumed that was wasted DC current since the "zero" was now sitting at half rail. As previously mentioned, the current needs to not reverse so the coil's magnetic field polarity does not alternate between N and S.
 
Last edited:

dendad

Joined Feb 20, 2016
3,323
I am a bit confused not since audioguru said removing the cap would cause the amp to run hot. I assumed that was wasted DC current since the "zero" was now sitting at half rail. As previously mentioned, the current needs to not reverse so the coil's magnetic field polarity oes not alternate between N and S.
Yes, exactly.
That is unavoidable in what you have asked for, using the TDA2030.
What is your actual application details? More info may well produce a better solution.
 

crutschow

Joined Mar 14, 2008
24,394
The output wave form would be intact, but at only half the amplitude achieved with push/pull.
No.
The peak-to-peak load voltage is still near the supply voltage to near ground.
The difference is that the DC average voltage is now 1/2 the supply voltage instead of zero.
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
44
No.
The peak-to-peak load voltage is still near the supply voltage to near ground.
The difference is that the DC average voltage is now 1/2 the supply voltage instead of zero.
OK. I got it. And I assume the amp's specified wattage needs to be down rated accordingly, perhaps by doubling the load resistance. But if I am only running the TDA2030 at 12VDC, it might not matter. I will try it and see.
 
An air-core coil is used at FM radio frequencies.
An audio amplifier does nothing at such high frequencies.
With the power supply at only 12V which is the minimum for the TDA2030, the maximum output power sill be very low, a series resistor feeding the coil will further reduce the coil power.
Will the input signal be DC? What band of frequencies?
What will it be used for?
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
44
Thank you for your further advice. It is just an experiment so the usage is not conventional, as you rightfully point out.
 
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