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I have a traslation (in Portuguese) of a BFO transistorized metal detector from Electronics World magazine, I think 1963. Each stage of the circuit is in separate decks in metallic box. According the TRANSLATION was found a coin at a depth near 1 meter (3 feet) in dry terrain... I'm searching for the original article by W.E. Osborne. One of the supossed advantage respect others BFOs is two transistor as mixers, one for each oscillator, and the necessary separation of the oscillators and the mixers and audio. The box have three decks: in the center the two mixers, the audio part and the meter. In the left compartment the fix oscillator and the speaker. In the right deck, the variable oscillator, the batteries and the potentiometer. The tune is via this potentiometer,no variable capacitor. The coils are internal and external, this is, one more big and the other small: an inner coil in the center, derivation of the first more big coil. I WANT THE ENGLISH VERSION!!! See the schematic:
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With a BFO design like this you would you would just about get a coin at 3 inches. Not 3 foot. These simple BFO designs are ideal for beginers because the are easy to get going. One big problem I have found with BFO detectors, is the tuning. Large variable capacitors are difficult to get hold of these days, and designs that use a pot to tune never have the range. There is an excellent method used to tune a BFO as described on I have built this one myself. It works well and was quite easy to get going, but did not go very deep. http://home.clara.net/saxons/bfo.htm I had in the past a Garrett BFO that cost about £150.00 some 25 years ago. This used a crystal osc for the reference and a large variable cap for tuning. But it did not go any deeper, and was no more stable than the Saxon DIY job above. The best BFO I ever used was an Arado detector. The VFA 90. This had a search frequency of 9khz. This is very low for a BFO. This was mixed with a reference frequency of 9 mhz in some way. This was a very pleasant detectos to use. Great on a salt wet beach with very good discrimination against iron, and very stable. Wish I had kept it. -
These simple BFO designs are ideal for beginers because the are easy to get going. This was a very pleasant detectos to use. Great on a salt wet beach with very good discrimination against iron, and very stable. Wish I had kept it.http://www.metallodetector.narod.ru/...e/superBFO.rarComment
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Thanks the both. The Russian files contain errors??? can't download. Respect the Arado BFO, where I can find the schematic?Comment
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Won't work for me eitherComment
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Also all the downloadbles files... See Russian LRL, Super BFO, etc., but nothing!Comment
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Strange, all normal off me. Please, attempt push - "save object as". Maybe herein cause...Comment
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Yes, is strange, download exist, but the program show errors. Maybe my winrar version can't support cyrilic alphabet. Please, do you can upload for us in Mytemdir the pdf file of the Super BFO, also LRL Rus? Thanks in advance.Comment
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Ok, very good! Thanks for your positive inputs. Tell us: what is the LRL Rus?Comment
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Sorry, but "LRL Rus" is not any Rus LRL device...
This only translation the strange article on Russian. Look please:
http://www.mytempdir.com/393232Comment
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Got both the BFO designs now Thank youComment
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BFO
Does any one have a circuit diagram for the arado vfa 90,bfo detector.Comment
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