Metal locator

[RKC]

G"day,

can anyone inform me what type of detector this is?
http://www.siliconchip.com.au/cms/A_111477/article.html

My uneducated guess is that its not a PI on VLF detector ... maybe a BFO.

Regards,
Rob (RKC)

[Carl-NC]

Looks like a variation of BFO. Instead of mixing the coil frequency with a ref freq, it uses a F-to-V to convert the coil freq to a voltage, and then compares that to a ref voltage.

- Carl

[aft_72005]

Hi , it is not BFO . at BFO mix of two oscillator ,giving beat frequency .
At this circuit frequency changing ,convert to DC voltage , than compare
Beat regards.

[WM6]

Basis of present idea probably pull root from BFO but is in middle point some simplified (or complicated - depending on the view) to BVO.

Suppose that used frequency here have to be relatively low instead of HF that only works by BFO.

Good idea worth to experiment with.