Automax V4 Mod

		Quote:			Posted by bountyhunter
	on another note I see your into computers. I own a computer company,I can do pretty much anything with a computer I want, except for illegal things, but I have a ton of used parts, and even more software. If you ever need anything let me know and I will help you out.

I forgot to say, the two transistors that feed the meter, the piezo will have to go from collector to collector, to get enough current, and use one of the 5 v to 15 volt type, they have a built in driver. Oh, I just thought of a problem... to avoid  wrong polarity, connect the same as the meter, otherwise the circuit will require a bridge, also, for insurance, place a diode, in series with the piezo, with the diode stripe to  the positive end of  the piezo, which should be a red wire.

If you use a meter, as well, set the balance so the piezo does not sound but there is some reading on the meter. I will have to redo this diagram and work a bridge of 1N914's into it.

goldigger

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I have one of those PCMCIA readers that fits in the 5 1/2 inch bay, I don't know if it will work for windows 3.1, what are you working on that requires a part like that for such an old operating system. just wondering. I will hunt it up, and if i find it send me your mailing info a maybe a couple of bucks and a few for shipping. I was using it, I built a pc based wireless router with it when wireless first came out, it was a COR, central office router, no os installed, just parts and a small script to run it, man it was cool I could feed wireless signals to about 100 people with it, and use it for a backbone for other towers. I just noticed the plans up top there, thanks so much i will have a go at it and see if i can make my own PCB for it. I just learned how to do it last night, I was up all night teaching myself how to use PCB123 and I think I got it down ok to do simple PCB's like this one.

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		Quote:			Posted by bountyhunter
	The image states the chip is a LM NE565 but in your text you wrote LM555, which is correct? I am using PCB123 and am having issues finding the LM NE565 to put in the   I doubt if you could do an LC oscillator, like that and have it remain stable. BUT!! I came across  a circuit using an LM555 chip that uses an untuned loop

In the case of a pinpointer, an unstable LC oscillator in a BFO isn't really an issue. All you are trying to do is locate a target. The stability of the oscillator would be needed if you were trying to ID the target or get the depth.

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		Quote:			Posted by bountyhunter
	Thanks for all you help, I have one more quick question and then I will leave you alone. I have an old JetCo metal detector, It's a old BFO Md, could I make a ferrite coil for this and use it? The PCB is not very large, I could relocate it into a project box and then I would have a pin pointer, its not very deep seeking but its all I want. But I will still take those plans you have for a pin pointer. But I was just thinking again. It seems that whats gets me into trouble.

It might be more trouble than it is worth.... a big board is not too good in a pinpointer. Actually, I more or less answered this question in my email, also. It is possible, a couple of things need to be determined: 1) the inductance of the search coil and 2) the frequency it operates at.  If it is really low frequency, it takes a lot of fine wire, to wind that coil, of course it helps to have low frequency type ferrite rods, to begin with.

What I have for rods is medium frequency stuff, for 500 kHz to 5 or 6 mHz, but as a phase shifting inductance, it should be OK. Of course.... I might get something from Amidon.

Ve skall see.

goldigger

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Well I did it, I took an old Jetco BFO and turned it into a pin pointer. The board is really small with not much on it. I by trial and error figured out the coil, So I am now making a new coil that is smaller yet to test it with. It's not bad at all, how I did it I'm not sure, but I do know that I can adjust the dial and make it detect from 4 inches away down to 1/2 inches, so I have a more sensitive pin pointer, when I get it boxed up and everything is done I will post some pictures of it. Thanks for the help, and encouragement.

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