How I turn a DC current on and off really fast?

I want to make a DC current (from a battery) oscillate between full voltage and zero voltage (not negative) really quickly, at least 30 Hz. I tried using an electromechanical switch, but the current from the battery is too low to produce any appreciable electromagnetism, so the switch didn't work. I tried... show more I want to make a DC current (from a battery) oscillate between full voltage and zero voltage (not negative) really quickly, at least 30 Hz.

I tried using an electromechanical switch, but the current from the battery is too low to produce any appreciable electromagnetism, so the switch didn't work.

I tried using a transistor circuit, but it didn't work either. Again, I think it's because the current is too low to use with the transformer that's used to regulate the transistors.

Anyone else have a solution? I'd rather have it be solid-state, but if the solution needs moving parts that's fine, as long as it works.
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