Convert DC Power to AC Power

Converting DC into AC involves switching the supply (e.g. from a battery) on and off repeatedly at a fast rate. Devices which do this are referred to as "Choppers". Attaching a coil of some kind (inductor, transformer or similar) will induce a current in the opposite direction to the original when the switch is open. This page outlines two methods of chopping the current, one using an electromagnetic buzzer and the other using an SPDT relay.

Steps

With an Electromagnetic Buzzer

1. Wire up an electromagnetic buzzer between your DC source and the AC load. The buzzer is an electromagnet for current reversal and also works as a chopper.

Without an Electromagnetic Buzzer

1. This method is more complicated than the first but will do the same job if you do not have an electromagnetic buzzer handy.
2. Wire up the relay so that the coil is in series with the normally closed terminal on the relay. This is effectively how an electromagnetic buzzer works. It may be necessary to wire a capacitor (approx 100uF) across the coil terminals to reduce the frequency or else it may not work.
3. This circuit is useful where either low voltage low current AC is required or can be wired up to the primary of a step up transformer to produce high voltage.

Tips

• The value of the capacitor in method 2 is reasonably elastic; 100uF will give quite low frequency AC, if a higher frequency is required a lower value of capacitor can be used. Electrolytic and non-electrolytic capacitors can be used as long as the voltage across the coil is not too high.
• The buzzer must be an electromagnetic buzzer as they work by opening and closing a switch rapidly whereas a piezoelectric buzzer works by supplying a voltage to a crystal which vibrates when electrified and therefore does not chop current.
• There are many other ways to produce a chopper, all you need is something that will switch the current on and off quickly.

Warnings

• As noted above,this can be used to produce high voltage, while high voltages are fun they are also dangerous so common sense must be exercised. Electric shocks hurt.

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See also

• Make a Dynamo Easily
• Rewind an Electric Motor
• Test a Transformer
• Check an Electric Motor
• Maintain a Generator
• Connect a Portable Generator to a House
• Size a Transformer
• Produce Electricity from a DC Motor
• Make an Electrical Transformer