Need one. Farmer with a metal detector

[yhl]

Need one. Farmer with a metal detector. Recycling old metal. Metal detector circuit

[maikl]

Need one. Farmer with a metal detector. Recycling old metal. Metal detector circuit

Hi yhl. This is for you:

[mikebg]

Hi yhl. This is for you:

Maikl, please attach the metal detector circuit! The farmer has such targets buried in the field, but need circuit diagram.

[technos]

Poor yhl. I think he meant to say "I'm a farmer who needs a metal detector so I can find metal to recycle from the fields. I need a circuit diagram so I can build one."

[homefire]

Simple and Cheap!

[yhl]

bfo metal detector

Need to search for iron, BFO circuit coil 30CM, aluminum shielding to do

[yhl]

Improvised Scrap Metal Detector

I need a circuit, I made a metal detector. Do metal recycling industry

[WM6]

I need a circuit, I made a metal detector. Do metal recycling industry

I think, homefire suggest you a good one BFO in post #5.

There is no problem to build bigger coil for suggested BFO (eg 30 cm diameter) if you keep the same inductivity. If this is problem, we can calculate for you. You can also use very good coil calculator here developed by Qiaozhi.

What of use is asking again and again? Better go on building.

[maikl]

I need a circuit, I made a metal detector. Do metal recycling industry

As far as I understand our friend has a stick and a box.He needs to put a detector in a box (some old used).I will need to probe at the end of stick.I still recommend the previous image in pos #2.Since in post # 5 complicated for you.

[yhl]

Need transistor BFO metal detector Circuit

[yhl]

ĤILP

[yhl]

Need transistor BFO metal detector Circuit

[Geo]

Need transistor BFO metal detector Circuit

http://www.bobsdata.com/metal_detector/index.html

[mikebg]

IMPROVEMENTS

I have several suggestions for modification and improvement of the BFO project in www.bobsdata.com:
1. To reduce the operating frequency in order to diminish the ground signal. At operating frequency 494 kHz a small change of height (distance sensor - ground) will cause audible alarm as the presence of target.
2. For best results, must have a minimum linkage between both oscillators. For this purpose it is better to use shielded potcore for L2.
3. The mixer diode D1 operates with large signals. This means that not necessarily use germanium diode; an 1N4148 operates well as BFO mixer.
4. Q7 transistor to be powered directly from battery voltage in order not to load stabilizer. Its collector should be grounded by an electrolytic capacitor.
5. Battery to shunt with an electrolytic capacitor.
6. Varicap and potentiometer to be used instead variable capacitor C5 .

[Krzysztof]

Hi Mikebg.
Generators from posts # 13 work with small power (0,5 mA), resistors R1, R2, R7, R8 are large. Signals will be about 10mV.
Then better diode is germanium.
Different generator to varicap has on example Sailler with capacitive divisor G - S.
Best regards Chris.