XR71 Operation Help

 
Reset button should function in two positions???
manual position???
automatic position???
When the jumper is automatska position then I reset to calm myself down detector.
In manual work reset does not work ..
It is ok or not???



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http://www.thunting.com/smf/index.php/topic,2887.msg232813.html#msg232813

uA556 is Fairchilds 556 timer.

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http://www.thunting.com/smf/index.php/topic,2887.msg232932.html#msg232932

I suggest you change your attitude. Also in the future you will receiving NO response from me to any of your posts regarding your current build or any other for that matter.   

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Xavier

		Quote:			Posted by satdave
	Thought you would have gathered that when i say striped alarm cable I meant from the main sleveing insulating the 4 pairs not the actual individual sleveing insulating the eight wires otherwise of course they would short unless wound as a web coil with gaps between each winding, which worth adding if doing it that way lwrs in capacitance considerably Hope that's put the record straight for anyone else who miss read my post.

Are you attempting to use this wire for a coil?

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http://www.thunting.com/smf/index.php/topic,2887.msg233768.html#msg233768

Well, Satdave, if you look at the characteristics of twisted pair wiring, you find that they are wound to keep audio frequencies from leaving the wires and keeping RF from entering the wires. It's very, very inefficient for coil wiring as I have demonstrated here before in other threads. Because of the DC characteristics, the experimenters such as yourself believe you are saving time by winding three or four loops and wiring them in a daisy chain. In fact, what you are doing is diminishing your field strength due to the AC characteristics of twisted pair wiring.

You need a bare, varnish or lacquer coated wire, scatter wound and then varnished or potted into place for the best efficiency in a metal detector coil. If need not worry about the DC resistance until you determine the total output power match. The DC has absolutely nothing to do with frequency. Only the inductance and total impedance affect frequency. Not only that but the coils MUST be built to be off of the main frequency by a minimum of 3db and a maximum of 6db to get the maximum field size and minimum field collapse time. While you may get satisfactory results by toying with things as you do, you will not get optimum results that way.

Basic electronics theory isn't quite good enough with metal detector circuits because you are trying to make a circuit that has a counter intuitive design incorporated into the theory of the device. In other words, most people think you have to have perfect tuning for everything to work. In actual fact, you have to have limited DE-tuning for things to work properly. When you wind a coil to work perfectly, you luck out because of imperfections in the windings. If you wound it with a perfect match, you'd get zero output. That's what you get in a tuned circuit. Plenty of folks here have found that out. Ask Xavier about perfectly matched coils and his results. That 3-6db de-tuning is optimum for a metal detector. If you can get it to work in a bandpass mode with that amount of de-tuning, you optimize your circuitry.

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