[SOLVED] pulse induction metal detector

[malik_123]

pi metal detector schematic

i am trying to build a PI metal detector
for it i made the research, which states that with the presence of the metal the pwidth of the decaying pulse increases
can any one guide me how to made a circuit that could detect the width of the decaying pulse and with this we can detect the presence of the metal

or
how the commercial Loop detector work


i searched and found this schematic that is of the Pulse induction type ,
**broken link removed**

please help me that how can a peak of 120 to 150 vlts can be measured by this ciruit
and what is the rule of the integrator amplifier

 

[malik_123]

hammerhead metal detector

t please help me that how can time of the decaying pulse be measured

and how can this circuit works

 

[A.Anand Srinivasan]

pulse induction metal detector schematics

use a comparator to find the time when the voltage of the pulse drops below a particular value,,,,,

 

[raghuram_msc]

pulse induction metal detector circuit

dear buddy,

The question is with the timer......how wold it "know" when it should start counting and when to stop? Again the counter cannot be analog it has to be digital! i.e, we need an adc in between! What rise and fall times are we expecting??

regards,
sai

 

[A.Anand Srinivasan]

pulse induction circuit

when the pulse rises it triggers the comparator to high so that the clock gets gated to a counter and the counter counts the number of pulses and when the pulse falls below a particular voltage level the comparator goes to low state and the clock is not sent to the counter and the count in the counter gives the number you require....

i didnt see any ADC in this block i'm describing.... there are many ways to solve the same problem....

 

[BANKNOTE]

pi metal detector circuit

YOU WILL FIND MANY OF YOUR ANSWERS HERE. GEOTECH FORUM.

**broken link removed**