I'm trying to create an oscillating magnetic field following a sine wave (around 1hz). It has to run of a battery, so I need a sine inverter.
I've tried using PWM together with a L293D h-bridge, the problem is that the coil should receive around 2A of current and the resistor needed for the low-pass filter reduces the current a lot making the electromagnet get almost no current. (maybe using another capacitor fixes this but I honestly don't know). The signal does not have to be highly accurate, but when looking at it with an oscilloscope, it should definitely still look a lot like a sine wave.
Is there another way to create low frequency high amperage sine inverters?
Use an Arduino with a DAC (digital to analog converter) to generate an analog sine wave signal, and send the output via a capacitor (to block the DC component) to a high power audio amplifier with a frequency response extending well below 1 Hz.
Post a schematic of what you built. I suspect that the only problem is the resistor. The coil itself should be enough of a low pass filter to produce a sine output.
The other reason for the schematic is that if I understand you correctly and you're tracking an incoming sine wave, then all you really need is an amplifier.
If you use high frequency PWM there is no need for a LPF - the inductance of the electromagnet will do that for you. But dont expect to see a smooth sine wave if you look at the voltage across the magnet - you need to look at the current through it.
You may need a bipolar supply, and you can use a simple transistor amplifier to increase the power.
You might also consider putting a non polarised capacitor across the coil calculated to be resonant at 1Hz, you will then need much less drive current.
