Controlling the Hidden Beast

[Alan in Little Washington]

Rob, that should work just fine! The DC might momentarily try to start when you flip the SPDT switch (unless you are really quick :-D ), but that shouldn't be a problem.

 

[ptt49er]

What is the sensitivity of the photocell? I've acquired 10 bright LED's and a convertor with a 5v DC output. I've done a little research and talked with the guys up in the EE dept. at school. All I need now is a resistor and the gumption to try to wire it up.
If I can get something worked out, would you guys be interested in buying the parts and I'll wire'em up?

 

[McRabbet]

Rob, that should work just fine! The DC might momentarily try to start when you flip the SPDT switch (unless you are really quick :-D ), but that shouldn't be a problem.

Alan, I realize that for the short time it takes to move the toggle from the On position (through the center Off) to the Service position that the power to the control relay drops and the DC contactor will start to close. It should just be momentary and I don't think it will cause any real problem -- on the plus side, this sequence does break the Red wire from the photoeye before making connection to the hot side, thus eliminating any possible harm to the photoeye circuitry. And it insures that the bin can be serviced under lighted conditions. Once complete, the switch goes back to the On position and the DC can start.

Okay -- now it's your turn to design a simple flasher circuit for the bin full indicator light in the shop! I read somewhere that Jim's strobe/siren puts out 110 decibels when activated -:jiggy:- my poor dog would go nuts and so would LOML!

 

[McRabbet]

Sounds like an interesting option to the 7 watt candelabra bulb (which puts out a low level of light similar to a candle flame). They cost about $0.20 each. The photoeye didn't come with any sensitivity specifications, but I have tested my mockup of the circuit with a 6" clear plastic jar across the beam and I dumped saw dust into it -- it tripped the circuit only after there was a pile of sawduct blocking the beam (the dust in a stream did not trip it).

How expensive would an LED array be?

 

[Alan in Little Washington]

I just ordered a strobe/siren similar to the one Jim did. There are a bunch on Ebay from many sellers. I just looked for the best price/shipping and came out at about $18 total. I plan to put foam, tape, silicone sealer, or whatever it takes, in the siren hole to dampen the noise!

FYI, I'm gonna post some pics of the portable high dust alarm shortly.

 

[Alan in Little Washington]

Sounds like an interesting option to the 7 watt candelabra bulb (which puts out a low level of light similar to a candle flame). They cost about $0.20 each. The photoeye didn't come with any sensitivity specifications, but I have tested my mockup of the circuit with a 6" clear plastic jar across the beam and I dumped saw dust into it -- it tripped the circuit only after there was a pile of sawduct blocking the beam (the dust in a stream did not trip it).

How expensive would an LED array be?

I had some problem with tranmissivity through the 9" flex on the Oneida I used for my testing. I had to increase the wattage of the illuminator from a 7 watt bulb to a 15 watt bulb. Even with that, I got a few false alarms when we were really hogging off wood with a 15" planer. The alarms cleared almost immediately- part of the problem may have been insufficient flow/air supply that work to dilute the chip concentration. My home unit has never had a false alarm.

Achieving adequate intensity isn't a problem, but the 15 watt bulb does put out a bit of heat, but I wouldn't want to replace it with something expensive. I am trying to keep the costs down.

 

[ptt49er]

Looks like a led array is going to be pretty cheap...I'll let you know more after I can get back into the lab at school and get this wired up. The LED's are highly directional so hopefully you won't need as much light as w/ an incandescent.

 

[ptt49er]

What is the size of the pocket the LED cluster needs to fit in?

Early indications are showing that 100 LEDs can be had for under $20 and resistors are even cheaper. So if a ac to dc converter is available (think cell phone charger) wiring a LED cluster up doesn't look too expensive. It probably won't be a pretty as a commercial unit, but it won't cost $50 a piece either.

 

[McRabbet]

Phillip,

Here's a few pictures of some of the key components. First is Alan in Little Washington's 7W light source shining through a ~3/4" hole behind a sealed plastic window in the metal connector tube at the base of his cyclone:

and then the photoelectric sensor that is mounted opposite (threaded section with sensor is ~5/8" diameter)

Next is the reflector equipped bulb that Fernhollowman (Jim Murphy) used on his Clearvue. He used a candelabra bulb too, but rigged it in a flashlight reflector to provide a stronger beam that had to pass through his "clear" flexible duct above the bin.

In his most recent implementation, Alan used a 15W bulb because his prototype had to shine through the "clear" wall of flexible duct and the sensor was 9-10" away.

So here is your challenge -- light source that is reasonably collimated (parallel beam) that will shine through a 3/4" diameter hole. In lieu of a "wall wart" transformer AC-> DC power supply, is it cheaper/easier to make a small power supply integrated with the LED electronics? Alan's latest unit fits in a standard waterproof PVC LL or LR conduit elbow with a single wall plug for power (Photoelectric unit needs 110V power).

 

[ptt49er]

So here is your challenge -- light source that is reasonably collimated (parallel beam) that will shine through a 3/4" diameter hole. In lieu of a "wall wart" transformer AC-> DC power supply, is it cheaper/easier to make a small power supply integrated with the LED electronics? Alan's latest unit fits in a standard waterproof PVC LL or LR conduit elbow with a single wall plug for power (Photoelectric unit needs 110V power).

Getting the collimated beam isn't not a problem as the LED's are extremely directional. The 3/4" hole shouldn't be a problem as there are some rather bright LED's out. I will look into the AC-DC conversion. The main reason I was looking into using the "wall art" transformers is because almost all of us have an old cell phone charger kicking around that could be sacrificed. The LED's only need a few volts and a scant 20 milliamps per light to burn.