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    Combine laser beam with LED

    That's kind of offensive anorlunda. So just because this is a fun hack for a toy, it's beneath the mean of this forum? Do others feel this way? Why would I go to a hobbyist forum for answers about optics? I've had some great responses here about water flow for my rainbarrels and water...
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    Combine laser beam with LED

    I want to create a visible pattern of light from 1-5 feet away. The pattern would have a bright dot in the middle (ala sniper sight) visible in bright light at 5 feet. The cheap toy pointers seem to work just fine. It would also have a filled circular pattern around the dot, 8" in diameter at 4'...
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    Help with water pump calculations

    Good to know. Thank you.
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    Help with water pump calculations

    The chart only had a few entries. Lucky for me one was 15' head. But in thinking about it, assuming the hose is the same diameter as the pump port, isn't the flow just proportional to (Max head - App head)? Where App head is the head needed for the application. For example at an 'App head' of 0'...
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    Help with water pump calculations

    I found a pump (Rule IL200) that had a chart of lift vs flow so I got it. Just for fun here are the numbers: Max Flow 3.3 GPM Max lift 25' Flow at 15' (my application) = 1.3 GPM So it will take a couple of minutes to fill my 2 gallon container. Thanks to all for info.
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    Help with water pump calculations

    I have a rain barrel 20 feet below a deck. I want to pump water from the rain barrel up to a small container (2 gallons) once a day. I'm thinking it should take less than 15 minutes to fill. I've found a pump I like that has the following specs, but it may be too powerful, but it's cheap ($15)...
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    Senior Controls Engineer Interview Questions -- Suggestions Please

    After decades of interviewing engineers, I have finally settled on the best way to choose them. The most important issues are how well they will get along in your group, what work experiences they have had and how good they are at solving problems. Sure, there must be a high level of skill for...
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    Thevenins equivalent problem

    The easiest way to solve this is by superposition. Create the first Thevenin equivalent from the 1500 and 750 resistors in lower left sub-circuit. Create the second Thevenin equiv from the 1500 Ohm resistor at the top. Now by superposition, connect the two Thevenin equivalents to the Output...
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    What will be the total resistance of ideal voltage source?

    I think maybe you are confused about the calculating the equivalent impedance (resistance in your case) of a circuit. There are 2 circuits to draw. The first circuit is the Thevenin equivalent of the circuit. In your case, it would be an ideal voltage source with a 0 Ohm series resistance. This...
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    Please explain curious behavior with my rainwater barrel

    I did some quick experiments with the rainbarrel which is currently full. 1. Both sides of the Y are wide open. By raising and lowering the end of the irrigation hose and always keeping the rest of the hose below the Y, the level gauge follows the level of the hose end. 2. Both sides of the Y...
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    How to configure a T connection for graywater collection

    Because of drought conditions here in California, I am building a graywater collection system. One aspect of this system is the collection of water from the sink while it is running just to get hot water. So the idea is that whenever I need hot water in the bathroom (for shower or sink) I run...
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    How can I calculate the vacuum pressure in Y-junction?

    While I can't answer your question, you may be interested in the discussion of the problem I was having with a Y adaptor. See Please explain curious behavior with my rainwater barrel
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    Please explain curious behavior with my rainwater barrel

    This makes perfect sense to me (not necessarily meaning it's correct). I really like your example of the hose in the rainbarrel. If this is the correct explanation, then I should be able to poke a hole in the barrel slightly above the bottom and attach my clear tube there. Since there is no...
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    Please explain curious behavior with my rainwater barrel

    I don't have a siphon setup. There is no inverted U shape flow. But the ejector idea seems like the right track.
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    Please explain curious behavior with my rainwater barrel

    Thanks for the reply. I'm not convinced of the explanation though. I don't see how the 'distributed pressure drop' explains this behavior. For the tube to drain completely means that the pressure at the 'Y' is 0 (relative). How can this be? This means I could start cutting the tube down to the...
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    Please explain curious behavior with my rainwater barrel

    I have a barrel that collects rainwater from the gutters on my house. At the bottom of the barrel is a manual 'faucet' with a round handle for turning the flow on and off. On that spigot, I have installed a "Y" fitting. One side of the "Y" goes to the irrigation hose which I turn on when the...
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