A Simple design based on a TDA0161 IC that appears to give better results
than the Discontinued CS209 and draws very little current from a 9 volt battery.

More Details to come

Created "February 4 2005" Updated "June 21 2005"

I obtained this chip in a Surface mount package,
than I made an adapter PCB to convert it to a Plug in Dip Package.
Pictures of the will be coming later.

This particular circuit was built with an LED Indicator.
There are Two LED's Shown in the Schematic, Both do Exactly the same thing.
I was just Playing with it.

Battery voltage can be up to 35 volts, but it doesn't add
to the sensitivity.


Depending on the Coil Inductance, Changes to the Potentiometer values and caps are Necessary.





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 Basic Schematic-1

 Advanced Schematic-2
This Modification in Advance Schematic-2 "Will Make this detector More Sensitive",
by using a "Manual Reset" to help eliminate the IC's, "Built in Hysteresis".
Use Standard Trimpot for the 10K and 1K Adjustments.
Note: Other Coil values can Also be used, if you also use the Appropriate
      Values for the Trimpots and "CX" Capacitors. These are the values I used.

Here is How to do this:

1) Make Sure there is NO METAL Near the Coil.
2) Set the Fine Adjustment to a "Mid Position".
3) Adjust the Course Adjustment to "Just Turn on the LED"
4) Than adjust the Fine Adjustment to Turn OFF the LED.
5) Now "Very Carefully" adjust the fine adjust to "JUST TURN the LED Back ON"
   and take "Careful Note of this Setting Position".
6) Now Just Back off this Setting a "TINY BIT".

LASTLY:

Pushing the "Manual Reset" Should now Turn Off the LED.
Than Placing metal towards the coil will turn it back on.
Pushing the Manual Reset, again turns it Off for doing another search for metal.

Play with it and Have Fun.




 

Click On Picture to make it Larger.


 Circuit Board, "Still to come"


 PCB Overlay, "Still to come".



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All Imformation in this Article is "Copyright protected".

 Chemelec 
 *Copyright © 2005*