Any interest in a cassette tape -> 3.5 mm adapter? (1 Viewer)

[Hatsuwr]

Hope this is the right forum. Not selling anything here, just gauging interest, and would be glad to talk about any of the technical details of it.

Still need to see what models/years this would apply to, but my '04 LX 470 has a tape player, but no 3.5 mm connection.

It's easy enough to inject audio into the tape player and just keep a tape inserted to trick it into playing. Not bad, but you have to deal with the tape reaching its end, the motor noise is annoying, the mechanism is going to fail eventually, and you definitely need to cut the traces to the audio chip if you don't want issues with static. To get audio to play from the tape player input without using an actual tape, you need to emulate the reel rotation sensor and the player's position sensor.

I have the initial design done for a small board that would just plug into the socket for the tape player. Takes a bit of disassembly to get to, but nothing difficult. This version just has a 3.5 mm port. I'm doing some experimenting with adding Bluetooth, although no idea how much success I'll have there. Would be nice to have that on the board, but there are plenty of standalone Bluetooth adapters out there that could just plug into the 3.5 mm port.

 

[Live to Ski]

not sure what the advantage is over a blue-tooth cassette gizmo.

Also, not sure about others, but I burned a huge amount of time in my youth makeing custom tapes. Have not got around to digital tranfers. Super easy to just throw a tape in vs looking at your player and almost getting into an accident.

with the age of our rigs (and drivers), not sure it's worth upsetting the apple cart (no pun intended).

that's not my story and I'm not sticking to it.

 

[Hatsuwr]

not sure what the advantage is over a blue-tooth cassette gizmo.

Also, not sure about others, but I burned a huge amount of time in my youth makeing custom tapes. Have not got around to digital tranfers. Super easy to just throw a tape in vs looking at your player and almost getting into an accident.

with the age of our rigs (and drivers), not sure it's worth upsetting the apple cart (no pun intended).

that's not my story and I'm not sticking to it.

Main advantage is just audio quality, plus reliability I suppose. Shouldn't really need any manual input or visual attention after initial setup. Doesn't really make sense to do if you're invested in a tape collected though, thanks for the feedback!

 

[Rhetoric]

There are a few manufacturers of Bluetooth modules that wire in line with the stock system. Grom Audio is one. I have their BT3 unit and it simply adds another source called “CD Changer” when I press the CD button. From there I can stream. It also has a 3.5mm input or even a USB input option that I never got around to installing.

I can also toggle back to the DVD changer and when I get the itch I can listen to my cassette collection. I leave my vinyl at home.

 

[crimsonaudio]

Are you talking about something like this?

Amazon.com

 

[Live to Ski]

Are you talking about something like this?

Amazon.com

the cassette adapter I use is blue tooth. No wires. Otherwise the same.

 

[Hatsuwr]

There are a few manufacturers of Bluetooth modules that wire in line with the stock system. Grom Audio is one. I have their BT3 unit and it simply adds another source called “CD Changer” when I press the CD button. From there I can stream. It also has a 3.5mm input or even a USB input option that I never got around to installing.

I can also toggle back to the DVD changer and when I get the itch I can listen to my cassette collection. I leave my vinyl at home.

I knew about the Grom, but didn't know that it acted as a separate input, that's interesting! I haven't taken a look at the CD/DVD side of things yet, but that opens up some more options.

Are you talking about something like this?

Amazon.com

No, the tape player mechanism would be removed an a small board put in its place. I'm just reusing the board from the old mechanism in this picture (the vertical amber one) for testing, but the final product would be roughly the same size.

 

[Hatsuwr]

Well, after a bit more testing, I found I was able to get this done with just a 1 Hz 50% duty cycle frequency on both ES/POS lines. Frequency and duty cycle need to be fairly close to these values with this method, but a single 555 timer does the job just fine.

If the signal is interrupted, for some reason it won't continue to play from the 'tape' unless you ground the LOAD line. I assume that the head unit thinks a tape error has happened in this case and wants the tape loading switch cycled so that it thinks a tape has been reinserted. I've only had this happen when intentionally interrupting the signal, but when I get this onto a board I think I'll take over the noise reduction button's input as a way of cycling the LOAD line. The noise reduction button only has functionality in regard to the tape player anyway.

Next up when I have more time to look at it is adding Bluetooth. As a basic level that should be fairly easy, but getting the forward/reverse/play buttons to interface in a way that can control the connected device will be a little more complicated. I'll need to get a new cassette player mechanism for some testing there since mine didn't survive the experimenting with different inputs...

I did have some luck finding a compatible connector for the 20 pin receptacle on the head unit for the tape player. The Molex Picoflex line with a 1.27 mm pitch fit fine except for the plastic polarizing tabs. The receptacle isn't polarized, so you just need to trim one of the tabs off.

 

[GremlinMobile]

I think your target market is like 3 people.

 

[Hatsuwr]

Here's the diagram for the circuit. Really simple. As mentioned, if it doesn't initialize automatically the first time, just ground pin 11 (LOAD) a few times when pressing the tape button. Should be all automatic after that.

For connecting the audio cable, pin 1 is the audio ground, pin 2 is right channel, and pin 3 is left channel.

I'll probably hold off on making any PCBs until the Bluetooth side of things is ready, but these components can honestly just be soldered directly to the connector with no issue. I soldered a headphone cable to the underside of the head unit circuit board instead of to the connector so I wouldn't have to mess with rerouting it every time I wanted to test something.

Oh and there are four resistors in my picture here because I only have resistors in multiples of 10 Ohms. One 1 MOhm in parallel with two 1 MOhm in series gets you around 666.7 kOhm. If you just get a 680 kOhm resistor then it's a lot cleaner.

 

[Hatsuwr]

Alright, after a bit of testing, it seems as if it occasionally forgets that it's been told there is a tape loaded. It's very infrequent and I haven't been able to identify a cause. The emulation of the ES/POS lines still works perfectly, but I'll be adding some way to manually trigger the LOAD line. Ideally, I'll be able to do this by repurposing one of the existing buttons that only has a function related to tapes (like the tape button itself, or the noise control), but we'll see.