Originally posted by Zicos
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good evening Mr. Franco.and to everyone. i made the 7812 circuit .. but i used 5 batteries (18650). because i had her.the sensor now has c9(680pf),c13(680pf),c14(680pf) and c2(2 capacitors in series (2.2pf)....output voltage without crystal is 0v with copper antenna. .....and with 40 cm flexible cable again 0 volts and when the antenna turns the output voltage is again 0 volts. the output voltage with crystal is 5.49 volts when I touch the antenna the voltage does not change it stays the same. in the garden test it catches the signal it was getting from a longer distance. but close to the house it is getting other signals I don't know for sure it is getting it... when I can I will also go to the field to test and let you know what it did..
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Hello Mr. Franco When we want to measure the self-oscillation of the circuit, we remove the crystal from the circuit and adjust the potentiometers p3 and p2. Should the antenna be connected or disconnected?Originally posted by FrancoItaly View PostThe important thing is that there is a variation when touching the antenna, normally it is a decrease. Obviously it is important that it works in the field.
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hello mr franco... i went to the field but the machine was not catching the target. when adjusting the sensitivity with which pontesiometro do you do it????? the sky and ground effect was there..the compass effect was not. unless I increase the sensitivity more.. how to adjust it?????
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when calibrating with crystal and antenna when i touch the antenna the output voltage does not drop or rise... when i put the antenna amplifier the output voltage goes up.... only if there is auto oscillation in the circuit the output voltage goes down when i touch the antenna without amplifier but also with antenna amplifier... without oscillation how can i achieve reduction of the sensor output voltage when i touch the antenna??????? should there be a change in sensor output voltage when touching the antenna to detect the metal effect?? or does it work like this??? is one of the components at fault????? the prices of the parts are always the same used or do they change sometimes?????what do you think????? sorry for so many questions..
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i made another sensor to see what happens... and it has the same problem. when i touch the antenna the output voltage does not drop or rise it is stable... i use BC548c.. i used that antenna i have and the sensor output voltage is always 0volt without crystal.. with crystal it is 5.44volt with only one capacitor c2(1pf) .if i remove c2 the output voltage is 4v if i remember correctly... that way the output voltage drops when i touch the antenna..
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You talk about antenna amplifier, I'm referring to the original version which doesn't have it.Originally posted by Zicos View Posti made another sensor to see what happens... and it has the same problem. when i touch the antenna the output voltage does not drop or rise it is stable... i use BC548c.. i used that antenna i have and the sensor output voltage is always 0volt without crystal.. with crystal it is 5.44volt with only one capacitor c2(1pf) .if i remove c2 the output voltage is 4v if i remember correctly... that way the output voltage drops when i touch the antenna..
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.....in the 8mhz sensor..... (1)....in the calibration I used a piece of copper wire 40 cm without reinforcement (as I had it in the photo) and with a crystal the output voltage is 5.44 volts, when I touch the antenna the output voltage does not drop or rise it is always constant 5.44 volts.........(2) ......also (without crystal and with connected antenna without amplifier as in the photo the output voltage it's always 0 volts).....(3)....when i touch the antenna why doesn't the output voltage change????? what do you think is wrong????
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