Home-made cables connect Bluetooth audio adapter Home-made cables connect Bluetooth audio adapter

After buying a Bluetooth audio adapter at a yard sale, I just needed cables for audio and power. Buy them? No way.

How many times have you thought about buying something, then thought “I’m an engineer, I can figure out a workaround” or simply decided not to spend money? It’s happened to me several times.

Case in point. I have a room that triples as a guest room, guitar room, and exercise room. As a guitar room, it has my guitar (of course), a laptop with a docking station, and a JVC compact stereo system from the 1980s or 1990s. As an exercise room, it has a stationary bike. As a guest room, it has a couch that folds open into a bed, quite useful for when I needed to quarantine during my three (so far) bouts with Covid.

The laptop and stereo share the top of a cabinet. They’re connected from the dock’s headphone jack through a homemade cable with a 1/8 in. (3.5 mm) audio plug and a pair of RCA-type audio connectors to the stereo unit’s auxiliary input. In essence, the stereo is a big computer speaker. It has an FM/AM radio and a CD player, which I never use.

The exercise bike — I do use it — is across the room from the laptop and stereo, which is too far away for me to watch while exercising. It’s a laptop so I can move it closer — undocked. Unfortunately, the audio cable doesn’t reach the stereo unit from the bike. I have a headphone extension cable that can reach.

For a little money, you can buy a Bluetooth audio adapter. I’ve thought about it and decided it wasn’t worth it when I could use the headphone extension cable. That was until I saw one at a yard sale. Now I had one for just $3, saving me $20 over buying a new one on Amazon.

The Bluetooth audio adapter came with a power source. I paired the adapter with my phone. Using the home-made audio cable, I plugged it into the adapter’s headphone jack. It played perfectly.

The power source produces a 5 V, 150 mA output, something any USB port can do. Unfortunately, I didn’t have a cable with the right size barrel connector.

A homemade USB cable provides power to the Bluetooth audio adapter. You just need the parts and the tools.

Like many of you, I have used numerous “wall warts” and kept a few. The odds of finding one with the right size barrel connector are infinitesimally small. Lo and behold, I found a wall wart with just the right connector.

Everyone has extra USB cables. I found a spare that had the large, original Type-A connector, probably from a printer. I cut that connector, cut the wire attached to the barrel connector, and checked with a multimeter that the red and black wires were indeed the +5 V and power return (never say “ground”) wires. I soldered the wires and wrapped them in black electrical tape. I didn’t have shrink wrap, but tape will do. Now I can get power for the adapter from the power source or any USB port.

This JVC stereo unit and the stereo system in the living room –-FM/AM receiver, CD player, and dual cassette deck — both predate Bluetooth. I also have a turntable that’s in the basement. The stereo system is in a cabinet that I bought as bare wood and finished it myself. A TV sits atop the cabinet. Although we seldom watch it, the TV has an audio output that I connected to one of the two receiver tape inputs. Thus, we can use the stereo for TV sound. My 1974 Advent 2 speakers sound as good as ever.

RCA audio plug connects to a stereo unit’s aux sockets.

The stereo system in the living room is about 10 m from the kitchen, with no walls in between. Where do we spend our time? In the kitchen, of course. I have a small Bluetooth speaker in the kitchen, but there’s no comparison to the sound from the Advent speakers. Connecting the headphone jack from my phone (needs an adapter) is impractical because we can’t possibly be 10 m away from our phones. But wait, now I have the Bluetooth audio adapter. Its power source now resides in the living room connected to a switched power strip next to the cabinet. I can now bring the audio adapter to the living room if I want to play music from my phone.

Bluetooth audio adapter gets power from the laptop docking station’s USB port

Now that the receiver’s two tape inputs connect to the TV and the Bluetooth audio adapter. What about the dual cassette tape deck?

Bluetooth audio adapter connected to stereo

Here’s the audio adapter connected to a stereo receiver’s tape input.

What’s a cassette, anyway?

Yes, I could have bought the audio adapter, which would have come with both cables that I had to make myself. What’s the fun of that? Besides, I’d have nothing to write about.