I know that when walkman batteries become weak, the motor, and in turn the tape gradually slows down. This is the effect i would like, but so far i've only been able to shut the motor down entirely.

I'll say no more. No need for the rest.

 

(edit - snipped) Sorry I realised I said basically the same thing as Wayneh said.

 

Thank you everyone for your input, it's really valuable to me and i'm massively grateful.

Initially my first thought was to adjust the voltage, but it does seem that directly controlling the motor as described in the article i posted might be better. The only thing i wish to change is the pitch, and that does seem to be a straightforward way to do that (unless there happens to be an advantage in adjusting the voltage in terms of how that adjustment might effect the sensor?).

MrChips, what you suggested sounds great. I don't actually have the Sony models in my possession yet, just waiting for them to be delivered. Should be the next few days i hope. In the meantime i will try and track down a selection of LDR's and a multimeter in order to take the measurements you mention.

I will also try and get some images of the space i will be installing the piece in so you guys can get an idea of the level of lighting. It's quite bright, but it might be possible to dim somewhat if necessary.

 

While you're waiting for the Sony WM, let's discuss some design parameters.

Don't worry too much about the lighting level. We can adjust for that.

Is the WM playing music, voice or simply a tone?

So a visitor walks into a room.
What is the size of the room?
How far away the person has to be in order to be detected?

As the person approaches does the sound pitch change in steps or does it change smoothly?
If steps, how many steps should it change?
If steps or continuously, what would be the percentage change in frequency from max to min?

You mentioned that the pitch should fall as the person approaches. Does it have to be this way?
Would it be acceptable if the pitch rises?

Just some thoughts.

 

Have you considered the old-style dictaphone? These tape recorders had variable speed play so secrataries could transcribe (Type) the voice recordings. They had a foot pedal that allowed them to slow or speed up the recorded tapes.

Also, for an art installation, you might want to look for an old "loop tape". This was an ingeneous design for short films and audio tapes that didn't require rewinding once played - it would just cycle through over and over again. 8 track tapes and some Walkmans had a version of this feature (they would automatically play the other side once the end was reached).

Unfortunately, you are about 3 decades late for the cool technologies of audio tape. Most of the non-standard recording equipment and playback devices are very hard to find today.

 

MrChips, discussing the design parameters would be great, thanks once again.

The WM will be playing a tone. There will be two WM, each playing a different tone.

The idea is that when there is no-one near the installation the two tones will be in harmony.

When people begin to walk around the installation, the tones will change in pitch and drop in and out of harmony.

I have attached a picture so you can see the size of the room. This corner is where i will install the piece.

As you can see it is a relatively small piece. The double doors to the right are the entrance, and they will walk past the piece towards the other two doors.

I would like the visitor to be detected from a distance of around 2 metres if possible, or at least so they don't have to get extremely close to affect a change.

Ideally i would like the sound pitch to change smoothly.

The percentage change wouldn't matter so much, just as long as there is a noticeable change, and this change becomes more extreme the closer a person is to the piece.

It is likely there will be multiple people around the piece, so it would be best if a change could be cumlative; ie the more people surrounding the piece, the more extreme the change.

I would like it if the pitch fell. Musically i think that works better, and i'm guessing slowing the motor would cause it less strain. I imagine the motor running at standard speed when no one is around, and then slowing the more people there are moving around the piece.

It would be good if there was an element of sensitivity where changes could be perceptible quite obviously by a body moving in and out of range at walking speed.

Ultimately i don't want to be too precious. I realise this is probably a tricky thing that i'm asking. Really the important thing is that the sounds change (in an interesting and obvious way) when people are around the piece. Whatever you think the best way to make that happen is, i'm happy to go with it.

GopherT - I did think about those dictaphones (used to use them myself working in admin) but they are very expensive. Walkmen are fairly affordable, so it gives me a chance to experiment.

In terms of looping the tape, i've made sure to purchase auto reverse Walkmen models so that when it reaches the end of one side, it automatically flips to the next.

I do use tape quite a lot in my art (particularly VHS) but this is my first time using Cassette, and as i say i'm quite a novice so i really appreciate the help i have received from everyone on this forum!

 

Some more questions:

1) Both WM will be playing two different tones in harmony?
2) What is your meaning of harmony?
3) What is the tone frequency or pitch of each tone?
4) Will both tones fall in pitch or only one tone?
5) Does it have to be a cassette player or can it be an electronic circuit?

 

Hi MrChips,

Each WM will play one tone.

By tone, i suppose it would be more accurate to say sound, or sample. I will use a synthesiser to pre-record a sample onto each tape.

For example WM A will play a synth line in "E" and WM B will play a synth line in "C"

That way they will be in musical harmony when playing at standard speed.

So, think of the WM as two "instruments" playing in harmony.

Then, as people move around each instrument de-tunes and re-tunes in accordance with the various motion interactions.

As they each de-tune and re-tune randomly, they will fall in and out of harmony.

I would like to use cassette as this enables me to have complete control over what the "instruments" play. Also, manipulating tape is an important part of my practice, and as such, the fabric of the piece.

Hope all that makes sense?

 

You can buy endless cassette tapes or you can make them yourself by splicing the tape into a short loop.

 

That's great, i think i actually just managed to find some endless tapes on eBay, so that might just do the trick, thanks again MrChips. Appreciate that.

 

Using an LDR is a simple way of modulating the tape speed but I don't think it will be very effective in detecting persons 2 metres away.

Most motion detectors provide a digital output (on/off) after a slight delay. This would not be suitable for your application.

A better solution is to use an ultrasonic range finder, something such as this:

http://www.robotshop.com/devantech-ultrasonic-range-finder-srf04-1.html

Ideally, you want a senor that will put out a voltage that changes with distance detected. If one cannot be found it would be possible to modify this one for your application.

 

These ultrasonic distance sensors really require a microcontroller. Someone may be able to help you pull something together that is simple. When triggered by the user (or microcontroller), it sends out a short burst at 20kHz, then waits for the echo. When the echo is detected, one pin goes from +5v to 0v (or reverse - I don't remember exactly).

If this angle works for you, you can get these detectors by the bag full for $2 each on eBay. For example...
http://www.ebay.com/itm/5pcs-Ultras...177?pt=LH_DefaultDomain_0&hash=item1c33272309

or Amazon for about $5 each...
http://www.amazon.com/gp/offer-listing/B0089VA3AY/ref=dp_olp_new_mbc?ie=UTF8&condition=new

 

That sounds great. I'm based in the UK, and i managed to find these before:

http://www.rmcybernetics.com/shop/HC-SR04?language=en&currency=GBP

Would that do the trick?

In which case, what kind of modifications would i need to make MrChips?

GopherT, could you tell me a bit more about this microcontroller you mention, and what would be involved in constructing something like that?

 

Most ultrasonic range finders provide the range in a digital format. In the most basic form the output is a logic level pulse whose width is proportional to the distance to the object.

We can use a microcontroller to receive this information in order to modulate the motor speed. There might be simpler ways of doing this using analog circuitry.

 

That sounds great. Would an arduino do the trick? I've not got any experience with these kinds of things but a friend mentioned them to me when I was discussing the project.

Sorry if I'm a bit slow with replies this weekend by the way, I'm in Amsterdam for a couple of days.

 

Hi everyone. I'm back in England, and the Walkmen arrived today.

I made a mistake on one of the models; the two i have to work on are:

WM FX-443 and WM FX-423

The install period for the show is at the end of this weekend, so if possible it would be great to start getting the piece together in the next couple of days.

Where would you guys recommend i start? I should probably purchase the components i need now to make sure they arrive in good time.

Thanks again,

James

 

I say you're leaving it a tad late, mate.
Don't set your hopes too high.

 

I have a series of shows coming up after this one, but i'd really like to at least give it a try for this coming show as it will make a nice test run. I also have a festival coming up in late September that i would really like to work on this piece for.

Would you still be up for helping me do it? I'm very grateful for your help so far and feel we've made a lot of progress so i'd just like to see what we can do and where we can get to if that's possible?

 

Yes, I was going to suggest preparing for the next show. There is still a bit of electronics design work that needs to be done. I will look into the two WM for you.

 

Thanks a lot MrChips, i really appreciate that.