Hi, I have built a Electronic load using ESP+LCD+ADC+DAC and a Op-amp driving MosFets which sets the Current I want..
It works great.. But I don't want "just" a DC Load, I want to Use it For AC amplifiers as well.... So if I Use a Bridge Rectifier and filter capacitor at the input I should still be able to set current (watts) of the load.. (my thinking)... On the PCB I set pads for a 2200uF filter capacitor (on the input AC).. Now I am second guessing my choice as this could draw inrush currents that would be to much to high for some smaller random amplifiers.... Does any one have thoughts on this..
Any feedback on this would sure be appreciated...

 

A bridge rectifier and a capacitor create a totally non-linear load.
The circuit draws current in peaks, resistive loads do not behave this way.

To make your circuit work as a true AC load requires a bridge circuit and a control loop that is much faster than the applied signal.
Not that simple...

 

Hi, I have built a Electronic load using ESP+LCD+ADC+DAC and a Op-amp driving MosFets which sets the Current I want..
It works great.. But I don't want "just" a DC Load, I want to Use it For AC amplifiers as well.... So if I Use a Bridge Rectifier and filter capacitor at the input I should still be able to set current (watts) of the load.. (my thinking)... On the PCB I set pads for a 2200uF filter capacitor (on the input AC).. Now I am second guessing my choice as this could draw inrush currents that would be to much to high for some smaller random amplifiers.... Does any one have thoughts on this..
Any feedback on this would sure be appreciated...

Without an actual understanding of what you are presenting I see it as unlikely to be able to suggest a scheme to provide the equivalent of an actual resistive load.
AND, with no hint at all as to the power handling level ofthe desired load, we have no clues.
Consider that what you are asking for is a scheme to emulate a passive resistance of unknown capabilities!!

 

Audio amplifiers normally work into, and are tested with, the fixed load of a speaker, and the power is varied by changing the input signal level.
Why do you want to vary the load impedance electronically?
Testing can be done with a 4 or 8 ohm power resistor per the amplifier rating.

 

I do not recall ever setting a load current for testing a device other than a current measuring instrument. Testing power supplies, including DC power drivers for servo motors, we measured the current at some terminal voltage. Voltage is specified because that is the driving force, and current is the resulting flow of power. Usually loads are specified by their resistance, with lower powered audio amplifiers usually feeding speakers,as already mentioned in post#4. Higher powered amplifiers, (hundreds of watts) often have outputs rated at 70.7 volts or 141 volts, when they are intended to drive speaker loads in a wide area. Using a much higher voltage and loacl matching transformers greatly reduces the loss in the longer wires.

"Servo-motor amplifiers" are a different sort, very much amplifiers, but mostly driving "servo" motors in some motion control scheme. THOSE LOADS are also often replaced by resistor banks to allow testing. OF COURSE, those load resistances are selected to simulate the actual motor resistance fairly closely. Mostly they are fixed resistors because any load that is variable will make calculating the delivered power rather uncertain.
I have seen "electronic load banks" advertised, but the applications for their use are unfamiliar to me. Possibly some sort of testing that I have not had to do in my career.