One of the great ironies of the audio world is that the “old” car stereo players turned out to be more resilient over time than “modern” equipment, thanks to the use of cassette adapters. We have already discussed them on two occasions, but this time we’re going to explore the possibility of building one ourselves. To be honest, they don’t use many components, and the room for experimentation is enormous…
Adapting or “modernizing” audio equipment that lacks auxiliary inputs is an excellent project for any electronics enthusiast, but if one of the goals is to make no major or irreversible modifications, the market already offers some “ready-to-use” solutions.
One option is to purchase an FM modulator that converts Bluetooth audio into a “station”, and all you have to do is tune to the correct frequency. Another path is the classic cassette adapter, which in some cases also includes Bluetooth. However, users often have doubts about its quality. In that case... why not build one?
How to Build a Bluetooth Cassette Adapter
This idea brings us to the YouTube channel of Zafer Yildiz, known for a wide range of audio, video, and power supply mods. The first step is to find an audio cassette to serve as a ”sacrifice” donor, since we’ll need its shell. Power comes from a simple TP4056, paired with a compact 3.7V 480mAh battery, while the Bluetooth module is a JDY-62A (or one of its 18 million clones), notable for its ultra-low cost and ease of installation.
The trickiest part is installing the head, extracted from an old unit. Both its shape and the number of contacts confirm it’s a stereo head, but it needs some cushioning inside the cassette, which is achieved with the help of a pen spring and a generous dose of glue. The final step is connecting the head wires, which are soldered to the L-R outputs of the Bluetooth module.
What can we add? One or two things: The original patent for cassette adapters indicates the presence of two capacitors and two resistors near the head. Another option would be to isolate the Bluetooth module with a B0505S to minimize the chance of noise, and if none of that produces decent audio... we can always install the JDY-62A inside the unit, at the preamplifier output... but that’s another story.
Source: Hackaday
