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lee78

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  • Magnetic Levitating Turbine - Tinkercad

    I think the orientation of the magnets shown in step 6 is wrong. The turbine will levitate if all 6 magnets have their North ends pointing in the same direction. If the turbine magnet North is to the right as shown in the diagram, won't the turbine clamp down on the leg magnets that have North to the left?

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  • lee78 commented on lee78's instructable Tiny Underground Solar House
    Tiny Underground Solar House

    I moved in 12 years ago today.About 8 PM last month I was surprised to see an owl perched under the SW eave, only 18" from the window. And then another! perched on the adjacent bear bar (vertical steel pipe.) They looked carefully at or thru the window 18" away, but gave no sign they saw me inside, less than 20' away. It was not THAT dark, but I was mostly obscured and didn't move much. Reflections of surrounding forest (and owls) would be visible. They flew across the 15' window to perch in the honeysuckle vines in the SE eave. They perched on branches of nearby trees and continued to look in and around for 30 minutes.

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  • Automatic Water Barrel Filler

    I think that won't work for the same 2 reasons a conventional toilet cistern fill valve won't work -- 1) there is no pressurized water waiting for the valve to open, it must turn on the pump2) the pump will be turned on every time the water level falls an inch. To save the pump from starting so often we need to let the tank be almost empty before the pump starts.

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  • Automatic Water Barrel Filler

    Filling this water tank is not the same as filling a toilet cistern. The floats and relays allow the tank to be almost empty before the pump starts. But the toilet inlet valve will start the pump as soon as the level drops even one inch, and keep it full. The pump will get a lot more wear if it comes on after that slight drop in level. With a toilet valve, how would you keep the pump off until the tank is almost empty? You implied there would be no problem -- "The ball can just have a longer string to the valve." If you're referring to the string between the flushing handle and the ball valve at the bottom of the toilet tank, that won't affect the filling. The drain valve just makes sure the tank empties every time it flushes. This instructable's watering tank is not emptied ev…

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    Filling this water tank is not the same as filling a toilet cistern. The floats and relays allow the tank to be almost empty before the pump starts. But the toilet inlet valve will start the pump as soon as the level drops even one inch, and keep it full. The pump will get a lot more wear if it comes on after that slight drop in level. With a toilet valve, how would you keep the pump off until the tank is almost empty? You implied there would be no problem -- "The ball can just have a longer string to the valve." If you're referring to the string between the flushing handle and the ball valve at the bottom of the toilet tank, that won't affect the filling. The drain valve just makes sure the tank empties every time it flushes. This instructable's watering tank is not emptied every time water is withdrawn.

    We say DPDT but since we're not using the NC contacts a DPST would work for both latch and pump, if its contacts can handle pump power. This instructable already has one SPST relay big enough for the small pump, and a second SPST doing the logic of latching can replace the ATmega. I see your revised simulation could be used with a larger pump and shows the right power flows. I'm still confused about what relay pins the float switches connect to. If the power relay and latching relay have similar coil resistance I'd connect them like this.

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  • Automatic Water Barrel Filler

    The amp meter in the simulation shows me that current starts and stops appropriately as I click up and down the switches representing water level at the upper and lower floats. I assume the pump is running when there is current energizing the relay. Maybe I am missing some animation, I don't see any except switch position and power supply meters & knobs. I don't understand the wiring around the DPDT relay. Zooming in I see pins for coil, and both poles' common, NO, & NC but I don't understand which wire is connected to which pin. I think it is a different circuit than the DPDT one I described in an earlier reply.

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  • Automatic Water Barrel Filler

    Right, I have a well & pump system like that. I can use 5 gallons of water without the pump coming on. There's a 25 gallon metal pressure tank containing an air balloon which gets bigger and a water balloon that gets smaller as water is used. A pressure sensitive switch controls the pump, turning it on when water pressure falls below 20 psi. Then the pump runs and the water balloon expands (adding 5 gallons), the air balloon compresses, the water pressure goes up to 40 psi and then the pump stops. A pressurized system like this is ready to supply pressurized water to a toilet cistern when the float in the cistern falls even an inch. This instructable turns on a pump in an unpressurized system. How would you get water up to the barrel? I think you are advising connection to a pre-ex…

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    Right, I have a well & pump system like that. I can use 5 gallons of water without the pump coming on. There's a 25 gallon metal pressure tank containing an air balloon which gets bigger and a water balloon that gets smaller as water is used. A pressure sensitive switch controls the pump, turning it on when water pressure falls below 20 psi. Then the pump runs and the water balloon expands (adding 5 gallons), the air balloon compresses, the water pressure goes up to 40 psi and then the pump stops. A pressurized system like this is ready to supply pressurized water to a toilet cistern when the float in the cistern falls even an inch. This instructable turns on a pump in an unpressurized system. How would you get water up to the barrel? I think you are advising connection to a pre-existing pressurized water system, or you'd add a pump, pressure switch, and pressure tank so the pump doesn't have to turn on every time a toilet cistern valve falls an inch. I do not see how toilet fill valves, or ball valves, will work unpressurized. Everybody suggesting toilet fill valves please describe the system you're thinking of.

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  • Automatic Water Barrel Filler

    I think valves that let in water at the right level won't solve this problem because there is no water waiting on the other side of the valve until they turn on the pump. They don't want to leave the pump running or connect a pressurized water supply.

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  • Automatic Water Barrel Filler

    Or use a DPDT relay and make the second pole latch the relay. With the float switches and relay coil in series (top float - bottom float - coil) , connect the common of the second pole of the relay to the point between the floats. Connect the Normally Open contact of the second pole to the relay coil at the same point the bottom float connects. Then when both floats close and the relay coil energizes, the second pole circuit will close and continue to supply power to the coil even when the bottom float opens as the tank starts to fill. The latching second pole circuit is in parallel to the lower float. The relay stays energized until the top float opens.

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  • How to Make FLEX Sensor at Home | DIY Flex Sensor

    Thanks, now I understand -- the carbon is pushed into the paper far enough from each side to contact the carbon from the other side. I bet porous paper like newsprint works better than glossy paper.

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  • How to Make FLEX Sensor at Home | DIY Flex Sensor

    I don't get it. When the paper strip bends, the carbon particles get closer together on the inside of the bend, and farther apart on the outside. The resistance of the foil strips doesn't change but maybe the foil gets pressed harder against the paper, compensating for the increased resistance when the carbon particles get further apart. But you're measuring resistance from one side of the paper to the other side, not from one end to the other. How does the resistance THRU the paper change?

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  • lee78 commented on NEW PEW's instructable Homopolar Motor
    Homopolar Motor

    I'm guessing -- the battery will not last long, that is a low resistance path. If you turn the magnet stack upside down, it will spin in the opposite direction.

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  • lee78 commented on Phil B's instructable 555 Capacitor Tester
    555 Capacitor Tester

    Here's a simple 555 circuit (NO circuit board, 1 resistor, 1 LED, 1 earbud)https://www.uchobby.com/index.php/2007/05/29/lm555-tick-tick-tick/that will tell you the capacitance of the capacitor if you use an oscilloscope. "You can use this circuit to figure out the value of the capacitor, if you know precisely the value of the resistor. Display the ticks on an oscilloscope and measure the time between ticks. 137 beats per minute is .44 seconds between ticks, a frequency of 2.28 Hz. Capacitance in farads C = 1.44/(R*Hz). So (if my resistor were exactly 27000 ohms) the capacitor labeled “20 mFd” actually was 23 microfarads..000023 = 1.44 / ( 27000 * 2.28)"Cheap digital multimeters will tell you the precise value of the resistor.

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  • lee78 commented on lee78's instructable Tiny Underground Solar House
    Tiny Underground Solar House

    Here is an earth moving movie (5 minutes)

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  • lee78 commented on lee78's instructable Tiny Underground Solar House
    Tiny Underground Solar House

    Can I still add videos? I'll try with this 1986 arch raising

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  • Electromagnetic Pendulum

    Why doesn't the polarity of the magnet make a difference? As the pendulum approaches the base coil, the increasing magnetic field induces a voltage across the base coil. As the magnet passes over the coil and moves away, the decreasing magnetic field will induce a voltage in the opposite direction. Only one direction will activate the transistor since current won't flow thru the base-emitter junction if the voltage is the wrong direction. So the voltage on the base reaches turn-on threshold either as the pendulum approaches, or as it leaves, depending on the direction of the magnet's poles and the clockwise or counterclockwise winding of the base coil. Once turned on, the battery powered current thru the emitter coil generates a much larger magnetic field and as it increases it induces th…

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    Why doesn't the polarity of the magnet make a difference? As the pendulum approaches the base coil, the increasing magnetic field induces a voltage across the base coil. As the magnet passes over the coil and moves away, the decreasing magnetic field will induce a voltage in the opposite direction. Only one direction will activate the transistor since current won't flow thru the base-emitter junction if the voltage is the wrong direction. So the voltage on the base reaches turn-on threshold either as the pendulum approaches, or as it leaves, depending on the direction of the magnet's poles and the clockwise or counterclockwise winding of the base coil. Once turned on, the battery powered current thru the emitter coil generates a much larger magnetic field and as it increases it induces the reverse voltage in the base coil, turning off the transistor. (I'm disagreeing about the transistor becoming saturated, I think the transformer reverses the voltage on the base coil.) The timing of the pulse thru the emitter coil would be different depending on whether it is triggered by the pendulum approaching or leaving, and that depends on the polarity of the pendulum magnet. ?!

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  • Rotellino - 3€ Battery Free Contactless Bike Light

    I think the core of the coil is ferromagnetic. Why isn't a magnet attracted to the core and stay there?I know eddy currents in the rim generate a field that opposes the movement of the magnet, tending to make the rotor spin. But eddy currents in the coil resist its spinning. Looks to me like the coil is closer, more conductive, and more efficiently configured.

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  • Rotellino - 3€ Battery Free Contactless Bike Light

    I think the eddy current that is by far the largest is the one thru the LEDs, induced in the coil by the changing magnetic flux cutting the coil to generate the emf. There will also be tiny eddy currents induced in the rim (steel or aluminum) like in any conductor near a changing magnetic field. Are those eddy currents in the rim generating enough of a magnetic field to rotate the magnet ring? I don't think so, the magnetic attraction to a steel rim is rotating the magnet ring. (Or is "magnetic attraction" also an Eddy current on the scale of electron spin?)I'm surprised if this works with aluminum rims. Eddy currentEddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Eddy …

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    I think the eddy current that is by far the largest is the one thru the LEDs, induced in the coil by the changing magnetic flux cutting the coil to generate the emf. There will also be tiny eddy currents induced in the rim (steel or aluminum) like in any conductor near a changing magnetic field. Are those eddy currents in the rim generating enough of a magnetic field to rotate the magnet ring? I don't think so, the magnetic attraction to a steel rim is rotating the magnet ring. (Or is "magnetic attraction" also an Eddy current on the scale of electron spin?)I'm surprised if this works with aluminum rims. Eddy currentEddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. -- Wikipedia

    I don't think so. See reply to ajoyraman below.

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  • lee78 commented on DianaHM's instructable Hot Glue Airy Lampshade
    Hot Glue Airy Lampshade

    This is great! I think if it were thread it would collapse in a pile. I have 25 lb fishing line monofilament and I feel, it is stiff on a small scale like 10 mm or a half inch. Your braided line may be even stiffer. Maybe they're about the same thickness -- my old label says .021 I guess that is inches so * 25.4 = .53 mm, you used .55 mm. It takes about an ounce of force to make the monofilament buckle if I grab two places 10 mm apart and try to push them together. That's apparently enough "strut" for such a light structure. I can believe wherever hot glue joints are less than 10 mm apart, fishing line between them will be a strut with enough compression strength to hold the sphere shape. Stiffer line would hold shape with hot glue joints at a greater distance. My guess of 10 …

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    This is great! I think if it were thread it would collapse in a pile. I have 25 lb fishing line monofilament and I feel, it is stiff on a small scale like 10 mm or a half inch. Your braided line may be even stiffer. Maybe they're about the same thickness -- my old label says .021 I guess that is inches so * 25.4 = .53 mm, you used .55 mm. It takes about an ounce of force to make the monofilament buckle if I grab two places 10 mm apart and try to push them together. That's apparently enough "strut" for such a light structure. I can believe wherever hot glue joints are less than 10 mm apart, fishing line between them will be a strut with enough compression strength to hold the sphere shape. Stiffer line would hold shape with hot glue joints at a greater distance. My guess of 10 mm is based on me testing for a minute, and your photos show it works with hot glue drops more like 30 mm apart.I never tried hot glue with fishing line, I'm glad to know it holds. I suppose braided is better than monofilament. A drop of hot glue is MUCH simpler than many designed joints for tensegrity structures. When something deforms the sphere, the strength of the lines in tension and of the glue mean that the tensile network will not break, the deformation will happen only as the compression struts buckle. And fishing line is so resilient when it is bent, it pops back to sphere shape as soon as the deformer is removed, right? Maybe you have to do a little patting to push out big dents. I think your construction would hold ANY shape if you started with a mold other than the balloon. (and used many joints on tight curves so lines are straight.)

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  • lee78 commented on DianaHM's instructable Hot Glue Airy Lampshade
    Hot Glue Airy Lampshade

    I'm impressed! Designers of geodesic domes and tensegrity structures think hard about optimum strut and cable lengths and orientation. Maybe you've shown me a new tensegrity design principle -- if you have enough joints, the orientations and lengths can be random!

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  • lee78 commented on DianaHM's instructable Hot Glue Airy Lampshade
    Hot Glue Airy Lampshade

    I'm surprised it holds its shape! I haven't tried this so I'm glad you did -- I expected it to droop into a cylinder or pear shape if it were hanging from the plastic circle. Or flatten on the bottom resting on a table. But it stays spherical ?! How thick is that fishing line? I think the glue is mainly at crossings, not spread along the fishing line (that would make it stiffer).

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  • lee78's entry Tiny Underground Solar House is a winner in the Tiny Home Contest contest
  • lee78's entry Tiny Underground Solar House is a finalist in the Tiny Home Contest contest
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    • Tiny Underground Solar House
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  • lee78 commented on lee78's instructable Tiny Underground Solar House

    raccoon on table looking in door didn't see meI wasn't inside when bear cub saw reflection in door (right edge of photo) and ran off

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  • lee78 commented on lee78's instructable Tiny Underground Solar House

    The house design would need a longer overhang over the south windows or another way to shade them during summer given the lower sun angle in Alaska. Or maybe the floor would absorb more summer heat that you would get back in winter. Here deciduous trees provide summer shade and lose their leaves to allow sunlight to the windows in winter. The lowest outside temp I've seen is 3 F, (inside 44 F.) There may be a week or 10 days when it does not get above freezing outside.Owner-builder smugness compensates for snugness. Also, an air temp of 50 F is much more comfortable in here than in a poorly heated above ground house; I think radiant heat from the thermal mass of earth all around is more important for comfort than air temp.An electric blanket is the only heating equipment I routinely use…

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    The house design would need a longer overhang over the south windows or another way to shade them during summer given the lower sun angle in Alaska. Or maybe the floor would absorb more summer heat that you would get back in winter. Here deciduous trees provide summer shade and lose their leaves to allow sunlight to the windows in winter. The lowest outside temp I've seen is 3 F, (inside 44 F.) There may be a week or 10 days when it does not get above freezing outside.Owner-builder smugness compensates for snugness. Also, an air temp of 50 F is much more comfortable in here than in a poorly heated above ground house; I think radiant heat from the thermal mass of earth all around is more important for comfort than air temp.An electric blanket is the only heating equipment I routinely use, but dehumidifier, water heater, my 1982 refrigerator, a couple of incandescent light bulbs etc contribute their electric load in the form of waste heat. The power has not failed in recent winters, so I could use a portable 1750 watt electric heater, but I don't. I also don't use a portable kerosene heater except to test it. A carbon monoxide detector assures me there are enough leaks in the window walls so ventilation is not a problem. (Who thought to seal the cracks between the planks near the ends?) My sister sent a big BULKY sweater and a thermal blanket she designed and crocheted. The blanket has a section at chest level with an overlapping layer formed into two wide arm holes, so I can stick my hands thru to operate a keyboard without pulling the blanket below my shoulders. A wool ribbon 3 inches wide and 4 feet long is sewed to the top of the blanket at the ribbon's middle. I wrap the two ends of the ribbon around my neck, like a scarf. It keeps the blanket from slipping down when I sit up.

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  • lee78 commented on lee78's instructable Tiny Underground Solar House

    I like!

    On a moonless night if I don't leave a light on inside that is a problem even when I know the door is nearby.

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  • No, the heat used to vaporize water is wasted if your purpose is to raise the air temperature. While the heat from burning wood is raising the water temperature from room temp to boiling, that heat in the water IS added to the room and not waste BUT when the water reaches boiling temperature it stops rising in temperature. Lots of heat then goes to vaporizing the water at the boiling temperature. So the room gets humid with steam, but the heat used for vaporization would have gone in to heating air to a higher temp if the wood had been drier. Wet wood wastes heat because so much of the heat does not warm air or water, it just converts water to steam at constant temperature.

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  • lee78 commented on anil8tor's instructable Solar Heater for My Shop

    This 12' C-band satellite dish provided domestic hot water in 1983 and collected TV with a cassegrain feed. Sunlight was absorbed at collector, microwaves bounced off to LNB on dish surface.. I wrote the program for the VIC-20 (lower right) that computed the position of the sun every 5 minutes and adusted azimuth and elevation motors.

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