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    Advice on building a radio transmitter in the Radio Control band

    I'll have to understand your reply, thank you for asking the questions. Bandwidth. I gather this refers to use of the channel? I can intermittently use the channel, using the RF charging when needed. From what I read it, fair use is important, but not enforced. The actual devices will not be...
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    Advice on building a radio transmitter in the Radio Control band

    << Mentor Note -- post separated out of a different thread to deal with a separate question >> Hi, I am looking transmit as well as receive power within close proximity. Currently I am looking at 27.255 MHz AM in the citizens band. It is listed on Wikipedia and in statues I found to be for...
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    Could one use a capacitor to enhance a capacitive stylus?

    What I want to do is have a mono pole capacitor so that the tip size can be reduced. I'm probably concepting it wrong though to think that would work. Essentially it would be static electricity on a stick.
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    Could one use a capacitor to enhance a capacitive stylus?

    What I'd like to know is which direction is the field that is measured? into or out of the plane
  5. L

    Could one use a capacitor to enhance a capacitive stylus?

    I understand that. What I'm thinking is you could make a finer point without the need for periphery plastic like in these products: http://en.wikipedia.org/wiki/Capacitive_sensing#Styli
  6. L

    Could one use a capacitor to enhance a capacitive stylus?

    I don't well understand capacitance and its use in touch screens. Just had a crazy idea that you could involve a charged capacitor to enhance the accuracy of a stylus.
  7. L

    Controlling activation of a circuit with a moisture meter

    Well there you have it. Would I get the functionality I desire out of an arduino? minimum time..about 5 seconds? potentially could generate power from the flow. doubt it though
  8. L

    Controlling activation of a circuit with a moisture meter

    How often does water flow ? every 10 mins When not flowing is there air in the cell ? Yes While flowing, how often do you need to make a measurement ? Once How long do you expect it to run on a single 9V battery ? As long as practical...hard one to answer. maybe a month...
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    Controlling activation of a circuit with a moisture meter

    Hi, I'm building a make shift spectrophotometer. It's only concerned with a narrow bandwidth of visible light. I'm using two LEDs, one which is lit, the other which is co-incident with a sample in between absorbing light from the lit LED. I pass the voltage of the receving LED to an LM358...
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    Multi LED circuit controlled by photodiode

    This circuit seems nearly perfect from what i can gather http://www.electronics-project-design.com/batterytester.html According to the spec pdf, if i open up pin 9 it should go into dot mode.
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    Multi LED circuit controlled by photodiode

    OK, I have a stronger idea of what I am trying to achieve and will try my darnedest to articulate its requirements: Yes, it is essentially a voltage meter. I'm not sure of the range of voltages involved, 1-2V approximately. Would need to be able to fine tune the sensitivity of the circuit. I...
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    Multi LED circuit controlled by photodiode

    yeah I am a little aware. They're voltage controlled switches in this example?
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    Multi LED circuit controlled by photodiode

    Hi, so. I don't know a lot of electronics but this is effectively what I'm trying to create: A photo diode controls the circuit, I assume they give out a current proportional to the intensity of the light it receives. The ciruit, depending on the light intensity will light up different...
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    Want to set up a constant magnetic field to do experiments under

    I..don't really understand. I want the titanomagnetite particles to align to the field...hopefully creating directional microstructure It wouldn't need to be too long, will have to do some viscosity calculations to see how long it will take
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    Want to set up a constant magnetic field to do experiments under

    The concrete will be made with iron sand. Maybe that will provide something analogous to an iron core. I was thinking of using a computer power supply, on the 12V rail. Bit confused as what to do about the amp load. The power supply has maybe 15A? on that rail. I have some 0.63mm enamel...
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    Want to set up a constant magnetic field to do experiments under

    Hiya, So I want to do some experiments with concrete curing under a magnetic field. The samples would need to be approximately a 2" diameter tube maybe 8" long. I'm not that aware of how a magnetic field would behave any more, been awhile since I did any physics outside of classical...
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