Using earbuds/iphone earpods with a crystal radio

Earbuds/iPhone earpods with crystal radio.

To use earbuds/iPhone earpods with a crystal radio you need to insert a transformer where the crystal earpieces would normally connect to a crystal radio. The jack for the earbuds would be connected to the transformer. Technically speaking, this is for purposes of impedance matching. Below is a diagram for one such crystal radio and some sample photos.

Crystal radio with crystal earpiece.

Crystal radio with transformer and jack going to earbuds.

Diagram with crystal earpiece.

Diagram with transformer and jack going to earbuds.

In the photo below are shown the transformers I've tried. Note that the transformer needs to be a step-up or step-down transformer. I'm not certain that a one-to-one transformer will work. The three smaller ones all gave around the same results. The large microwave oven transformer didn't work as well; the sound was too quiet.

Transformers I've tried with earbuds.

Connecting to the earbud/earpod

Earbud/earpod connectors usually have three places to connect on them. As shown in the following diagram, the tip is for one earbud, the middle is for the other earbud and the place nearest the plastic molded casing is common to the two.

Where to connect to the earbud jack.

How to determine which side of the transformer to use where

A transformer has two coils/sides and each coil has two wires coming from it. You need to connect the two wires from one side to the crystal radio and the two wires from the other side to the earbuds.

Here are some ways to determine which side goes where. See the corresponding diagrams and photos below. The side that connects to the crystal radio is the side:

that's labelled with the higher voltage,

that has the coil with the most turns, or

that has the highest resistance.

Determining using labelled input/output voltages.

Which side to connect where based on the voltage.

Determining using number of turns on the coils.

Which side to connect where based on the number of turns.

Determining using resistance of the coils.

Which side to connect where based on the coil resistances.

Video - Use earbuds/earphones with a crystal radio

The following is a video showing all of the above - basically how to make earbuds/earpods work with a crystal radio using a transformer.