Solid State Microdrive Cartridge?

[bwinkel67]

I just saw a YouTuber using a floppy disk drive to record audio, without changing the floppy hardware. The magnetic head on the QL seems to be somewhat similar to what you get in a cassette deck. I'm guessing it transfers changes in magnetic pulses to the tape. I would guess if you could play the tape through a cassette deck, it would make some noise, maybe static or maybe screeching?

I wonder if you could you create a solid state cartridge that just connects via its own tape head (similar to the way you had cassette adapters that allowed you to play music on a cassette deck from an MP3 player) and records mcirodrive pulses digitally in a 7 second loop? If the timing of the loop is correct, then wouldn't all it needed to do is read and write info when the microdrives asked for it? So you keep the actual micrordrive units and replace the tapes with a solid state tape?

Is that a crazy idea or doable? Could it be simpler than what's been done with SD interfaces for MDVs?

[Chr$]

I wondered about that in the past. If it were technically possible I wonder if the main issue may be finding suitable heads that are still being made and also, as the head is actually fatter (taller) than a cartridge, is there even a currently manufactured head available that would be technically suitable but also small enough to fit in a dummy cartridge and through the cartridge slot gap in the QL.

Wouldn't there also need to be some coupling to the motor wheel to move the 'tape'? Probably the development time and costs for such a project would make it a non starter. But I'd buy one!

[Chris_68]

Hi,

Cool idea!
The head is half the size compared to an audio cassette, my best bet is a head from voice recorder (dictaphone) might work.

[Pr0f]

Or perhaps a custom magnetic, but it would need to be 2 tracks. The other issue is power to the unit, as it would need to be battery powered most likely and a likely power source would be a 3v lithium cell. I suppose the motor would only need to drive an encoder wheel or something to give the tape motion detection. But I suspect timing could all be done in 'firmware'.

[bwinkel67]

Wouldn't there also need to be some coupling to the motor wheel to move the 'tape'? Probably the development time and costs for such a project would make it a non starter. But I'd buy one!

I think all that would be needed there is for the device to know when the motor was ON so as to then move the virtual tape ahead at constant speed (independent of the motor speed since the timing on the QL is independent of that). If the motor is OFF the virtual tape pauses at that location.

[bwinkel67]

The tape head on the QL is the same size as a normal cassette recorder...and if it doesn't have a sheath on it, I think is just wide enough to fit into the opening of the case...that part I need to look at more carefully (with regard to measurements).

[bwinkel67]

The cassette head on my old car adapter, seems to measure a little under 8 millimeters as it is slightly smaller than the fat end of the microdrive cartridge sleeve cover (which fits into the QL's opening). It looks like the QL's read/write head is closer to 7 millimeters. The one concern would be alignment of the heads, as on the adapter it is off-center seemingly by a millimeter more than on the QL's read/write head, though maybe may be due to the slightly larger size.

AliExpress sells tape heads but I haven't been able to see if you can buy them by sizes. So likely, finding the best-fit tape head would be important for this to work, but it may not be that Sinclair invested in specialty ones for their micrdorives back in the 80s.

[Chris_68]

Hi,

I might be wrong but the tape in an ordinary audio cassette is 3.8mm and just 1.9 mm or maybe 2mm for a QL same as smaller cassettes used for dictaphones

[Pr0f]

https://youtu.be/MMD-d-1erk4?si=IfUshVwNQM_8IGgh

some ideas...

[xelalex]

In addition to detecting motor on/off by checking for movement of the pinch roller (maybe with LED similar to an optical mouse, to avoid mechanical parts), you would also need to detect when to read and write. For this you have to check whether the erase coil is emitting a field, and as soon as it does, start reading what the tape head is emitting. Once the erase field is gone, you then switch back to replaying the data into the tape head. Seems all a bit involved, proper alignment could be difficult, and it might be very hard to get it working reliably. But would sure be cool.