Horn Speaker for a Crystal Radio

This horn speaker is an improvisation for my 'Loudspeaker Crystal Radio'.

Horn Speaker

It requires only 2 additional parts - a dustbin and a food container - with the crystal radio speaker itself serving as the driver.

In order to simplify the mounting, the speaker is made to drive from its rear while its front is sealed by the food container.

Horn Speaker details

Rubber based adhesive is used for assembly.

Audio output is considerably more than with the speaker in its normal enclosure.
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Loudspeaker Crystal Radio

This is the speaker variant of my series-tuned crystal radio with an alternative detector.

Loudspeaker Crystal Radio

Replacing balanced armature headphones (impedance around a few hundred ohms) with a low impedance speaker required the use of an output transformer.

A power transformer, with its inherent thick conductors, appeared to be the ideal substitute for a low-loss output transformer.

Trials with transformers rated 230V/24V-2A, 230V/24V-5A and 230V/24V-15A proved the last one to be the best.

Series-tuned Loudspeaker 
Crystal Radio - Schematic

Aided by the perfect match offered by my 'Homebrew Horn Speaker' and 60' wire antenna, reception of the lone local 200kW 612kHz AM broadcast station, located 20km away, was excellent.

Performance was also quite good using the parallel-tuned configuration.

Parallel-tuned Loudspeaker
Crystal Radio - Schematic

Related post: Compact Loudspeaker Crystal Radio
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