Counter for reel to reel tape recorders

[gilhooley]

Dear Arduino community,

I am brand new here, so please excuse me if I do something wrong or on wrong place.

What I need ?

I need to develop something with Arduino module (I did something before with Nano, but now perhaps I need to go with other module).

I need counter for reel to reel recorders (for example Akai or Sony or Revox). Counter should count in play mode from 000001 to 999999. When play stopped - counter should stop. When press FF - counter should counts fast in forward and vice versa if REW pressed - during rewind - fast countdown in opposite direction.

Push button for reset is needed, so if pushed during play, counter should go to 000000 and start counting from 000000 during play.

Is it possible to do this ? I need sensors on motor or somewhere (I know), but is there any completed and approved project ?

I had some thoughts about real-time counter, but I hope - this is not problem with play, but it is problem with opposite direction, FF and REW. Hopeless project - I think.

Any help is welcome. Thank you in advance.

Regards,

Boris

[groundFungus]

To be able to count and determine direction you need a "quadrature encoder", probably using IR light reflective or slotted sensors.  Hall effect sensors use magnets, probably not good for tape use and switches won't last long at the speeds that a reel can rotate.  How to mount encoders depends on the mechanical makeup of the unit and could be the biggest challenge.

[Paul_KD7HB]

Been too many years since I looked at reel-to-reel recorders/players. but I suggest you study your device a bit more.

In play mode, the speed if the tape past the read head is constant. The movement of the reel motors are such as to keep the slack between the capstan motor and each reel at a constant location. Same in rewind, except the capstan turns really fast.

Reel-to-reel recorders/players with counters count the turns of the capstan/pinch roller, not the turns of the reel motors.

Does your machine already have a counter? if so, you can figure out some way to replace the turns counter with electronic components. If your machine does not have a counter, there may be another model with the counter.

Paul

[DVDdoug]

Reel-to-reel recorders/players with counters count the turns of the capstan/pinch roller, not the turns of the reel motors.

It's been a long time for me, but I don't remember seeing a capstan turn backwards (except on auto-reverse machines).   Maybe  if the pinch-roller is in constant-contact with the tape it could be used somehow.

I don't really see a problem with "counting" the reel rotations.   Generally, the counter is used to find (or get close to) some position on the tape, but I don't think I've seen a minutes & seconds counter so it shouldn't have to be linear.

I think the mechanics might be the "hard part".  As long as you can mount a rotary encoder in a some  way to rotate with tape movement the electronics & software should be fairly straightforward.  

[dougp]

Maybe an optical mouse sensor?

[lastchancename]

RECORTEC made these 'add-on' counters many years ago for professional decks.



They used one of two methods -
1.   An extra low-friction roller with around 2/3 wrap to ensure good contact in the 'tensioned' zone of the transport.
2.   Or an add-on 'W' roller arrangement which provided local tension to ensure consistent friction over the count roller.

You could go deep, but that would be machine dependent - counting the tach from the tape path - hiowever you must remember the diameter of the supply & take-up reels will change as the tape moves - so the tach will also change if derived from those.

The pinch roller & capstan are only reliable in forward or reverse play modes - so that has limitations as well...

Also consider possibel slip when accelerating or braking - differs with large or small diameter tape rollers.
You could try really high-tech - and use something like an optical mouse - focussed on the tape... (sounds like fun) --- @dougp typed it as I was preparing the post !!

[DrDiettrich]

Any wheel can be used for the counter, provided that it stays in contact to the tape when the tape is moving.

[Slumpert]

What does the backside of your reel axles look like. 
Could you attach encoder discs internally to both reels?

[dave-in-nj]

if you have a way to add a roller to one of the existing, you could laser print an encoder and attach it to that roller. and use IR sensors or some such to read it.     get an old ball mouse and take it apart.  if you are both good, and lucky, that will have everything you need.

[gilhooley]

Dear All,

Thank you all for discussion and hints, but there is a few things that I should say...

1. If you can remember old reel to reel or tape decks...counter is going slower or faster if you at the beginning or at the end of tape. It means that counter is NOT connected to capstan, because capstan must ensure constant speed for tape traveling for example 4,75 or 9 cm per second. Capstan works independent, but with constant speed. It means that impulses should go from reel motors. they go slower or faster, if you are playing or going FF or REW.

Now...

2. If I do some chemistry on motors and can collect impulses (quadrature encoder) - how connect it to Arduino ? Is there any finalised solution?
3. How going back with counting in opposite direction?
4. Remember that for example Revox HAS real time counter which is not problem to start (simple timer), but how go opposite or FF or REW?

It seems that I have quadrature encoder on reel motor shaft and collect impulses for both directions.

Thank you, regards.

Boris

[lastchancename]

Reply #5

you must remember the diameter of (the tape) on the supply & take-up reels will change as the tape moves (from one to the other) - so the tach will also change if derived from those.