ROOSIE

What I have:• A transformer rated at 150VA / 30V (center tapped) / 5A• Speaker rated at 30W / 8 ohms (measured 6.3 ohms with my multimeter)Will use class AB amplifier:• LM4780 • Question:If I send +30V & -30V to this chip, I will get 45W at 1%THD+N: Is it possible to keep +30V & -30V but limit the maximum power to 30W? Is it by playing with the gain (feedback resistor value)?I read somewhere "...power amps at lower gains requires more input voltage to get the same power output, with the same speaker impedance".How to adjust/calculate the gain so that I get a maximum of 30W output with +30V / -30V power supply? I own the transformer already so I plan to use it as the power supply (+30V / -30V). It is center tapped. It is 30V-0V-30V.

Hi, I'm new here. I'm trying to build a simple LM386-based audio amplifier circuit. I've attached a schematic of what I've got.I've got a simple pair of earbuds plugged into the audio output end, and an FM radio plugged into the input end for testing purposes. I'm powering it off of a 9V battery.What I hear through the earbuds is a "click" at regular intervals. Listening closely, I can tell the "click" is actually a very short snippet of audio from the FM radio. (Just a single note or even less.)Again, I'm pretty new to this. Please don't hesitate to point out anything bone-headed I'm doing. All help is greatly appreciated!Thanks in advance.

I'm trying to build a Instrumentation amplifier that would do a 10uV -> 10mVamplification. The motivation is to measure uA currents on a small enough shunt resistor (1-10Ohm). For a proof of concept, I've built a circuit like the one below(png1.)with a distinction that I'm powering it with two 9V batteries and am using LM2902N as the op amps and Rg is somewhat different. It has much less that the required 1000x gain. However, when measuring the results for different input voltages, the gain seems to vary: png2. I was expecting it to be constant. · What is a reasonable place to look for the causes of the variations? · Cheap resistors? · Inadequate op amp? · Breadboard prototyping? · 2x9V batteries as power supply? · other?