Hi Bob,
Dont you like this low tech approach, no laser beams, hypersonic links and no lost fingers..

EDIT:
Added a sketch.

Attached Images

esp03 Jul. 22.gif (5.3 KB, 10 views)

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Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Seems a safer method than an IR beam (ONLY a metal material can activate crusher)
A simple capatance circuit could be intergrated when any metal is placed between the probes.
Perhaps just a metal ring in bottom of crusher tube at each end.
Most if not all cans are anadozied not painted so conductivity is not an issue.

 

http://www.uoguelph.ca/~antoon/circ/alarm2.htm
looks like this might work?

 

I would prefer my half - circle shaped electrodes suggestion

Only the bottom of the can is needed to actuate the circuit. If you put each electrode at the end of the can, the circuit will not work if the can is not long enough. Think about the dumb friend who prematurely crushes or deform the can with the hand watching the football game on TV

I also suggest to increment the lenght of the piston travel, to give to the user time to get their hands off the way of the crusher (the youtube man should drop the can and run scary before the piston crushes his hand, also the use of wood is not higienic)

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La Rotta

 

Hi All,

why don't we get back to the original threat? The OP asked for an electronic way to start and stop the motor. He didn't ask for safety advise though.

Menticol, how do arrange conductance measuring at the bottom of cans of different sizes? The probes must be kind of spider's arms to reach into the inside curved bottom for good contact.

IR-remotes have proved to be reliable in the past, and will be reliable in future. Sensing an object using an IR-barrier is also a very reliable way. All it takes is a timer circuit oscillating around 38KHz with short duty cycles at its output to drive two IR-diodes connected in series for sufficient output. The receiver can be a TSOP1738 which outputs a logic high if there is signal reception and a logic low if the signal is interrupted. Using the output to trigger a monostable and the output ANDed the motor can only start if both signals are high. (triggering the mono low makes its output high for the preset time and getting the IR-beam again the reiceiver jumps to logic high again). If there is any foreign object interrupting the line of sight between transmitter and receiver the motor wont be activated. That takes care of safety, not guaranteed that you put a can and a cat into the receptacle simultaneously, which cannot be recognized by the circuit.

Concerning the mechanical construction of such a device I prefer pneumatically driven pistons. They operate silently (with silencers at the exhaust port) and have almost no wear and tear.

This is about how it could look like. There are two pistons for safety reasons. If somebody reaches in he has to reach in the way to break his arm before the piston can do the job.

Regard to all

Hans

Attached Images

CANCRUSH.jpg (110.3 KB, 7 views)

 

Is somebody going to have a drink of a crunched can?

 

Maybe, who knows?? hahaha kidding, offcourse not, but the spills of soda on the wood, with the sticky I don't know the english word for that, ¿mound? of sugar... Interesting life will become to grow on your machine!

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La Rotta

 

It would be safest to use a key switch to turn that on.

 

... and the slowest possible way. This might be alright for private households.

For selling places like restaurants the throughput must be as high as possible.
One can per second makes a ROF of 60 rounds per minute. Crushing the daily average amount of 500 to 700 cans would still take 8:20 to 11:40 minutes.

A big restaurant in my vicinity "procuces" a full truck load of empty cans every week. That equals 60 cubicmeters of cans!

Hans

 

Hi Menticol,

I made some experiments with cans yesterday and here is the result:

Nor is the body of the can conductive, neither is the top, not even the opening lever. The only conductive part of the can is the buttom which is untreated pure aluminum. The film is comparable to the enamel on a copper wire to make induction coils.

Poking through the laquer with the probes of the multimeter each part becomes conductive. However it requires a sharp tipped probe or a pin to penetrate the laquer and some force too.

Using the conductance measuring method could easily be done by closing two insulated tips (from each other) via levers thereby poking small holes into the can, similar to a fork used to lift animals digestional leftovers. (Sh... ) This could be done without poking holes into the fingers by positioning the probes out of reach of hands.

Mechanical drives can malfunction, and therefor I better stick with the idea of IR-barrier detection.

Regards

Hans

 

Might be handy to consider the cleaning process early in the design stage. If I leave anything with sugar around the kitchen, ants find it immediately.

I think IR-barrier detection would be quite reliable, but IR-reflective against the bottom and/or top of the can might be even easier. Might also be more likely to reject improperly oriented (upright) cans. Upright cans would gum up the works of most of the designs I saw on YouTube.

 

Well it has been a pretty cool industrial design discusion, but I think the OP fell asleep waiting for the circuit. I'm too lazy to re-draw it, so I photographed it from my old book

If I have some mistake please warn me, I'm not very experienced


http://i74.photobucket.com/albums/i2...ol/Me23026.jpg


http://i74.photobucket.com/albums/i2...ol/Me23027.jpg

The hand writting on the receiver is to correct a mistake on the book, they forgot to add that capacitor.

To calibrate it, put Emitter in front of Receiver, and turn pot until relay turns on. Connect relay's NC pin to 555 timer circuit (mentioned posts before), so when the beam is broken the 555 is triggered.

I think the receiver's relay can be removed, and the 2N3906 colector be connected directly to 555 circuit trigger through a 2N3904 NPN.

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La Rotta

 

Sorry by double posting, editing was disabled

Nice job Hans! I have never imagined the top wasn't conductive, but only the bottom. There's a problem with the sharp tips as sensors / poking into the can. When the can is crushed, the sensors will be buried into the can, breaking them or changing it's shape.

The IR solution is more suitable, but harder to build for the inexperienced OP. So I suggest to use the flat sensor I mentioned before, wired to the 555 circuit also posted before

Attached Images

lata.JPG (27.2 KB, 4 views)

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La Rotta

 

Hi Menticol,

I also like the idea of capacitive sensing.

Concerning the OP I'm afraid to say that his approach is not in the right sequence. As he wrote me in an email he wants the electronics done first and then turn towards the mechanical part.

May be somebody else can convince him of the fact, that electronics work is far more flexible than mechanical.

He wants a lot of "cool effects" which have to be taken care of by knowing his mechanical design. If I plan to make a can counter and he decides not to have it I must redesign the circuit because a valid count has some influence on the control circuit too, meaning to employ some more logic in the circuit.

May be I'll go for some "cool effects" too and have R2D2 (Starwars) scream while the can is being crunched.

Cleaning of the machine shouldn't be any problem reducing mechanical parts to a minimum, that is, using pneumatic cylinders instead of oily gears, open sprockets and possibly chains. If the chassis is made of stainless steel you could even take the device to a car wash station. (after having removed the electronic part)
An additional advantage of a pneumatic actuator: No compensation necessary for different size cans. Just the stroke long enough to cover all sizes.

An inadvertantly vertically dumped can might (just to avoid the double can ) be corrected for correct positioning easily by shaping the "load" channel accordingly (like a bowl), so the can will get out of balance and tilt either way.

Experiment: Drop a can 100% vertically on a hard surface tilted 2 degrees. Guess how it will come to rest. (Top heavier than the bottom anyway)

Regards

Hans

 

Hey guys,

I did not fall asleep, just been looking for parts.

I can design the crusher and submit it to you for assistance with the electronics. I just thought that the electronics would be easy to adapt to the design by placing parts where they are needed. Like I said early in this thread, I do not know my way around electronics.

I will draw up a design and post it here for all to see. Thanks for your interest and your help.

Bob

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