Damping resistor

[nick holas]

hi,
How can i select the value for my damping resistor coil whitout a scope (it's for barracuda md).
thanks a lot.

[Carl-NC]

I suppose you could take a low-conductive target like a US nickel, start with an overly small damping R (overdamped), then increase the R until you get a maximum response. This ought to be done with the coil on top of the strongest expected soil mineralization.

[johnandles]

I suppose you could take a low-conductive target like a US nickel, start with an overly small damping R (overdamped), then increase the R until you get a maximum response. This ought to be done with the coil on top of the strongest expected soil mineralization.

Search the threads..Iam sure you will find an "Adjustable Resistor diagram" to determin the best value for damping.
Even without a 'scope' aim for best response.
Hope that Helps

[nick holas]

i understand what you mean ,i have to test with different metals to find the best resistor with a pot perhaps but with a multimeter isn't it possible ???or maybe a frequency meter or Lmeter ???
thanks for your reply
sorry for my college english.

[johnandles]

i understand what you mean ,i have to test with different metals to find the best resistor with a pot perhaps but with a multimeter isn't it possible ???or maybe a frequency meter or Lmeter ???
thanks for your reply
sorry for my college english.

Without a 'Scope' you have to adjust for best distance/ sensitivity setting.
No need for Lmeter or whatever,Providing your coil is within specifications.
Iam sure on this site as I replied before an adjustable damping resistor is easy to use.Once you have found your best detection depth..just measure with a multimeter the resistance and then solder in the resistor..
Hope this helps
John

[satdaveuk]

The comments posted on here are about the best you will get without a scope but to be honest you will will never get max performance without one its like trying to find a needle in a haystack.

Regards

[UFO]

It's not that bad lol.

I bet you could tune it to perform within 5%-10% of what you could do with a scope, easy.
I don't think the difference would be to dramatic.

Although a scope would make life easy.

[nick holas]

thanks all
i've tested those tips but i don't see (hear ) difference of distance detection (perhaps my coil ??)
i can find a nail at 25 cm deph (i think its not bad) but a gold ring at just 5 cm deph.
i've read other threads in this forum about barracuda and i saw "you must have 0volts in pin 6 of NE5534 if not move offset pot until having 0v .i 've turned max to 0 offset pot but nothing happend i only have 2.8v at this pin (with a 9v cell).

[Carl-NC]

If you adjust the offset pot and the output offset doesn't move, you have something wrong. Need to figure this out first.