Quote:
Originally Posted by abdou2014
I used with this version a ferrite antenna,
the antenna reacts to fresh precius metals and not to iron,
I need to know how many volts are needed in the point on the photo to have more results, thank you Mr Franco !
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At this point there is an alternating signal superimposed on a continuous voltage, there is no fixed value for good operation, it must be found experimentally. It is necessary to start with the whole cursor towards + 12V (alternating signal = zero) and increase slightly until you have at the X point a signal of about 2 - 3V from peak to peak. Tuning is not easy since the frequency is lower than the 8Mhz version and C13 / C15 may need to be increased. Due to the high gain of the sensor stage, measuring with the oscilloscope at point X could change the working conditions (maybe the sensor stage could auto oscillate). Sometimes it is useful not to ground the oscilloscope.