The Lucid Tech "MP3-Track" Adapter: Play MP3's through your car's original FM/8-Track radio!

In July 2008 I made a conversion adapter to play MP3's through an 8-track head unit, without major modification, and keeping the original appearance. The idea is simple enough so I'm probably not the first to do it, but I did get the idea and work out the design on my own. I posted this on a handful of Ford-related forums at the time.

I call it an "MP3-Track" cartridge. Basically, I gutted a crusty 8-track cleaning tape (any cartridge should work, but that cleaning tape was obviously useless), then disassembled a wireless FM transmitter for MP3 players. I chose the transmitter based on the likelihood of a fit, as its guts are transplanted inside the cartridge shell. When the finished unit is placed in the deck, the transmitter ends up right next to the receiver, so there's little or no interference. I bought a small horizontal-form-factor MP3 player that attaches to the label end of the tape cartridge and looks very nice.

The advantages are numerous: The car's radio remains 100% factory original bone stock, no expensive replacements or irreversible mods are necessary. Everything is contained in one removable portable cartridge so you can easily share and use it in any car with an 8-track radio. The in-use appearance is clean and integrated, unlike all those cables and crap hanging out of your dash. And formfactor gripes aside (sorry, iPod fanboys), it works with any MP3 player!

The guts of the system. You can see where I had to remove material from the cartridge shells for clearance, but this was not difficult.

I also had to use a different battery holder because the original, as built into the back of the circuit board, would not have fit. The one I'm using was a freebie I got from a countertop point-of-sale display crate (you know, the cardboard ones with blinking lights and stuff to get you to buy some useless thing you otherwise wouldn't waste $2 on).

I carefully cut some holes in the bottom side for the frequency switch and original power button. The transmitter is a simple press-fit this way, but stays securely in place. The selector switch fit nicely in that recessed area of the cartridge shell - this might be a dumb lucky coincidence as different record labels used various cartridge designs and styles over the years. Also most 8-tracks aren't held together (and easily opened) with simple philips screws... so maybe a cleaning cartridge really is just the one to use.

Closed up. For now I'm using Velcro to attach the player but you'll note I left ample space in the cartridge to cut a "dock" of sorts if I wanted to. The caveat of a "dock" is that it would only fit that one style of player, limiting the converter's aesthetic adaptability.

Not only is Velcro cheap and easy, but the player is slightly easier to reach (an inch closer) by not being recessed in the cartridge.

Installed in the car (of course I bought the color-keyed MP3 player model)! Note that if you push the cart in all the way, the tape mechanism engages and the radio no longer plays... So, only insert it just to that point. It sticks out maybe an inch further but this doesn't look bad and is actually helpful with easy reach for skipping tracks, etc.

If I were to produce or sell these, I'd probably have to make a few minor changes but for $10 (cost of the transmitter) and a couple hours of fiddling to convert, I won't complain.

Also, a better route would be something like those CD-to-Cassette adapters so it could use the tape player's stereo head directly, skipping the radio altogether. I understand there actually were Cassette-to-8Track adapters I could possibly cannibalize for parts, but those would have cost me a (surprising!) bit more to obtain.

I used the MP3-Track throughout the summer with no problems! Every now and then I'd get some minor static, and of course that vintage head-unit's amplifier can't handle all new songs that well owing to modern high-volume productions, EQ curves and low frequencies, but I am very pleased with the results. Most of the time it's crystal clear... within the original radio's limits of course!