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#2726
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Hi Franco
Do you remember what is the pk-pk voltage value of the composite signal that reaches the base of Tr2? I mean about the product of mixing especially when we hit the right harmonic across the LC tank. Approximately. Thanks in advance Merry Christmass and happy new year to all. ![]() |
#2727
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#2728
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Thank you Franco. I ll give it a try! :-)
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#2729
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Hi all
Hi Franco The input P1 trimmer seems that doesn't serve the purpose of its use. I tested two crystals 4M and 16M. The signal at the input of tr2 can not be less than about 50 mV. Imho, your initial design with many 1pf caps in series is a better approach for to increase impedance. A second issue is the input tank coil. More turns than 3 will give higher sensitivity and higher Q. I made a coil of 8T on a 6mm former to test. I'd like to ask if you have tested 90 degrees different orientation of the input tank coil than what you currently use. In other words, the coil on your board looks at the sides. Have you tested the operation when it looks forward? Regards |
#2730
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#2731
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Hi Franco
Thanks for the answer. What about if a commercial fm station transmits on the same frequency like your tuned input? Will your system saturate? |
#2732
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Near the FM transmitters, a few hundred meters, the lrl is useless, too many false signals.
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#2733
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Very useful notice tnks.
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#2734
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Hi Franco
Just to tell you that your circuit is amazing. Great technique, and to mention that sensor circuit doesn't need any modifications at all! Adjusted as to give me 1200mV at the output of sensor. Starts decreasing as i approach my hand close to the antenna at 40cm. When i finally touch it, it goes as down as 950mV. Almost 300mV decrement. Really great Franco. Thanks a lot. Its time for the indication stage. ps. I solved my issue at the input. The increased oscillator's signal across the tank circuit was due to capacitive coupling. It came at the right levels when i isolated oscillator in a faraday type cage. ![]() |
#2735
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#2736
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For sure it would contribute in to a more clean amplification of the effect, but if inside the box is not taken in consideration the interaction between oscillator and the rest of the device there would be no way for setting the input level at minimums (due to capacitive coupling). I used a 16Mhz crystal by the way. No stability problems and clean signalling. Tuned to 32Mhz.
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#2737
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I think I detected the iron frequency 68,490 khz.
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#2738
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What device did you do it
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#2739
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Hello Franco !
we have made the original version, we replaced the coil 3 turns with tsok ferrite. I think it goes quite well at 2 maybe 1 meter from a buried object with a phenomenon..the setting is very marginal just before the last led hits and when I turn it to the sky it hits gently..I detect with a slight inclination to the ground. do you think this is a normal function? |
#2740
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I am busy on a lrl working with a PIR
Good wishs for you and all[/QUOTE] Hello sir..can u update about this project using pir on lrl..Thank u..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2741
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#2742
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Hello Franco..I sent a private Message..this was regards to the partslist of your original lrl..I cannot visibly read the values especially ic1 and diodes..Thank u..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2743
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when there is no phenomenon there is no signal, you did not understand me..detects normally the phenomenon with very strong signals very close 1-2 meters when there is no problem when my direction is from north to south..but when I raise the antenna in the sky there is a signal from the sky..I make sure to adjust the device and have a signal up to the horizontal position.then I lower the device a little to the ground and the signal stops and I walk when I encounter a phenomenon the device emits a signal .. there is no signal continuously. ... basically I try to find the signals from the sky when they are connected to the earth ...
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#2744
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#2745
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I put the original lrl again, as it was privately requested.
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#2746
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Hello franco..Any idea about pcb e schema made by Dream man..is it ok to use?Thankbu in advance..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2747
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PCB FOR 20MHZ SENSOR
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#2748
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Good work, Mustefa
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#2749
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Hi liudengyuand..how did u made the curicuit effective?can u tell us more..
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#2750
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Hey Jhericku The circuit is effective by itself. Franco designed it very nicely. You don't need to change anything. It confirmed that detects only noble metals and no iron! Mine, it also can not detect copper Just tune it to a harmonic that gives a nice output and you are there. Location distance not more than 4-6 meters. Works every day no matter the conditions. It is just that depending on the day, the field sometimes is weaker but still detectable. If anyone likes to go deeper on this, then i suggest you to use a simple voltmeter instead of leds. ![]() ps. I use a 16MHz crystal by the way. No stability problems. |
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