The Crystal Radio Audio Matching Transformer is an 8 ohm to 100K ohm 12 terminal audio matching transformer.

The Crystal Radio Audio Matching Transformer maximizes a crystal radio's performance by matching the radio's audio output impedance to the headphone or earphone impedance. The Crystal Radio Audio Matching Transformer can also allow you to use lower impedance headphones and earphones with your crystal radio. Have you ever wanted to just use your earphones from an mp3 player with your crystal radio? With a crystal radio audio matching transformer you can.

The photo below shows the terminal locations. Terminal 1 is the common ground connection. Typically, the output of the crystal radio will be connected to one of the terminals between 8 and 12. The headphone or earphone will be connected to one of the terminals between 2 and 7. It is best to experiment with connection points until you achieve the best results.

Terminal	Impedance (Ω)	DC Resistance (Ω)
1	0	0
2	8	2.1
3	16	3.0
4	32	4.2
5	64	6.4
6	300	12.6
7	10K	156
8	20K	231
9	40K	332
10	60K	464
11	80K	556
12	100K	631

Dimensions: 1 5/16 inches by 1 1/8 inches
Terminal Spacing: 0.2 inches
Terminal Row Spacing: 0.9 inches