需要 晶体管BFO的金属探测器 线路

[mikebg]

CORRECTION of circuit diagram in post #30

TX CURRENT
In the BAD circuit, the TX current flows to supply rails from input pin 2 via stray capacitance and input protection diodes.
In the CORRECT circuit, the TX current flows to COM rail. Capacitor C2 stops the DC component of output.

OPERATING POINT
In the BAD circuit the operating point is not defined because there is no DC connection to pin 3. In the CORRECT circuit the operating point is defined by R1 connected to COM rail and stabilized by negative feedback via R2. Timeconstants R3C1 and R2C3 are enough small to suppress signals having mains frequency and interferences having its harmonics.

[zzy]

Boy with you in China are much more stringent laws in the field of metal detectors.Probably with you to school recently introduced Internet.You are using the Internet is not the right way.China State authorities follow your steps on the internet.My country has been communist, and I know how it works.Take heed, you can be arrested in the juvenile prison.當心你可以被拘捕，並被帶到一個少年監獄，貴國是危險的事情！

Boy,you answer is very Irresponsible,DO you ever know China laws?

Laws in the field of metal detectors？Nonsense！I have build maney metal detectors.No one dare arrest me.
and"follow your steps on the internet"?SOOOOOOOOOO stupid！
no one have spare time to do it.

[zzy]

yhl leave it is much difficult to create.This is the right thing for you: easy to create, cheap parts,low consumption, has a great depth of detection,with it you can find many more...

Cheater！ BIG cheater! do you know what you say?fool and stupid!
ONLY An idiot build it.
"easy to create, cheap parts,low consumption, has a great depth of detection,with it you can find many more"??
with it you can find a lot dog ****!

[maikl]

Cheater！ BIG cheater! do you know what you say?fool and stupid!
ONLY An idiot build it.
"easy to create, cheap parts,low consumption, has a great depth of detection,with it you can find many more"??
with it you can find a lot dog ****!

Hi zzy. I am in the beginning trying to help your countrymen "yhl".But when I saw that it is not worth the effort. Started a little kidding with him.There is a difference in the culture of "East" and "West".But I guess in China, there is humor and jokes? Does China abolished public executions in stadiums???

[zzy]

Hi zzy. I am in the beginning trying to help your countrymen "yhl".But when I saw that it is not worth the effort. Started a little kidding with him.There is a difference in the culture of "East" and "West".But I guess in China, there is humor and jokes? Does China abolished public executions in stadiums???

Hi maikl, I misunderstand you. but "yhl" is a beginner, we should give him a good start.
you have post the picture before,Called MOLE Detector. Some people really sold to our country, and sold $14000! So I really hate it!