TaidacentOPA541 OP AMP High Power Monolithic Operational Amplifier 5A Current High Voltage Audio Amplifier Sound Amplifier Board

Using this for a homemade PEMF machine. To drive the coil. The output signal is clean and noise free. High quality and expect it to last a long time. In my application will need a fan to keep it running cool.

Comes with a schematic and contact info. The sch. routing is correct but not some of the values. This device is DC coupled throughout. Easy to mount. Nice heat-sink size for forced air cooling or lower power natural convection. Layout looks very good. The terminals are not that good as it's hard to get enough torque on the screws due to the head design but I know good ones are spendy so they will do.In my case I'm using it as a buffer for my workbench so I removed R5 (a shunt), set the gain to unity and used SMA P1 as an input. Feeding it with +/- 15 Volt at 4 Amps from two supplies. I've used it to buffer my function generator and it's fine well past 100 kHz in sine. Seems happy with inductive loads. I tried speakers, motors, transformers and everything is well behaved. Buffering me bench supply shows the DC offset is nil and tracking is near perfect. Output noise is very low---less than 2 mV rms when sourced with my linear supply running 10 Volts.

This power ampifier uses the OPA541 power op-amp, the closest replacement for the venerable but discontinued National LM12. The OPA541, unlike the LM12, does include provision for output current limiting, a feature exploited in this product. For some reason the manufacturer also included a pre-amp OPA445 high voltage op-amp with a gain of 11 which feeds the OPA541 which has a gain of 3, giving an overall gain of 33. The inclusion of the 445 is entirely unnecessary as the 541 has an FET 4 pA input bias current and very low input offset voltage and bias current. The bandwidth extends from about 100 Hz to 90 kHz (50 kHz full power bandwidth). It is also interesting that the output from the 445 is AC coupled to the 541, eliminating the use of amplifier for DC signals when such performance could have been easily provided. The heat sink for the 541, while large, is mounted on the pc board in such a position that cooling by convective air flow through its fins is blocked.Both units I bought, running off of +/- 39 V power supplies failed driving very light loads with a 60 V peak to peak output. Purchasing a 541 replacement from a reputable U.S. distributor restored operation completely. As the principal attraction for purchase of this amplifier is its cost, with the single item price of the 541 running at about $25, the 541s used in this product may be seconds or knock-offs, so buyer beware.

I needed more power from my function generator in order to test power audio transistors. This inexpensive module did the trick.

Bought this to get higher current at different frequencies and works very well within the ratings. The board works for up to 100kHz. The board came with a schematic that was very helpful. It allowed me to modify the circuit for my application and get higher bandwidth.