Henry on coils

[Prospekteur]

....i know its a little bit a dumb question........I wanna know how i can know how much microHenry i need for a pcb wich i dont know from datasheet how much microHenry i need for this specific detector? How can i calculate how much Henry i need with no specific information about that?

Regards Prospekteur

[waltr]

Easiest is to read threads and study the schematics on specific detectors for the required coil inductance.
Also buy and read the book "Inside the Metal Detector" for general information on required inductance calculations.

[homefire]

Insufficient Data. What Flavor of detector are you talking about here ?

PI detectors are some what Generic on that value on coils. Higher or lower values can produce varying target responses. Smaller or Larger Targets, Target Type or Material can be some what enhanced or negated. As usual at the Cost of some other desired trait.

VLF using the required Operating Frequency you can juggle Known Capacitance and Inductance uH values to achieve what your looking for.

Options , Options, Options Eaaaa!

[Prospekteur]

"Insufficient Data. What Flavor of detector are you talking about here ?

PI detectors are some what Generic on that value on coils. Higher or lower values can produce varying target responses. Smaller or Larger Targets, Target Type or Material can be some what enhanced or negated. As usual at the Cost of some other desired trait.

VLF using the required Operating Frequency you can juggle Known Capacitance and Inductance uH values to achieve what your looking for.

Options , Options, Options Eaaaa!"

Im talking about Vlf....sorry i forgot to mention. But my question is answered now. Thank you both very much!

"Easiest is to read threads and study the schematics on specific detectors for the required coil inductance.
Also buy and read the book "Inside the Metal Detector" for general information on required inductance calculations."

I have this book....but the last time ive read in this book is over past two years ago. I will have a look again today;-)

Thank you guys!

[homefire]

One More Satisfying Day as a Not So Super Geo-tech Hero comes to a close. LOL

[Tim]

One More Satisfying Day as a Not So Super Geo-tech Hero comes to a close. LOL

I just had a horrifying vision of a middle-aged man with his red underpants over his blue onesie, sitting in front of the computer.

[homefire]

LOL, You have NO IDEA how close your are.

[Prospekteur]

I dont understand whats so funny? My english is not the best. Ive only had a question???

[homefire]

Your Question Was A Good Question. I was just making fun of my self. Ask as many questions as you need. We will try to answer them to the best of our abilities.

[Prospekteur]

Thats nice;-). I know that my question must be not sophisticated for experienced technicians in this forum. Im still learning ;-) And i have a lot more questions .........

The real funny thing is that i really wear red underpants in this minute and thought you talking about me.......LOL

[homefire]

LOL, No he was referring to Me. Funny part was he was almost spot on.

[Goaty]

Stop it you guys - I've got tears running down my face.

[Tim]

Ta dada da ta da...
Anyways, back on subject. By my limited understanding so far, the cap and resistor values around the first op-amp of the RX circuit will accommodate the TX frequency. But I am unsure if the values are increased or decreased as frequency is upped or downed (in laymans terms). I am presuming this will then throw out the values further down the signal path, and an oscope would be needed to explore the signal at each stage output.
The TX frequency can be changed by changing the caps in the TX oscillator circuit (as well as coil winds) and from my limited understanding the resistor values will effect the size and quality of the sine/square wave (is this right??) (laymans terms only please).
Perhaps someone with more experience could explain it better (in laymans terms) without the advanced mathematics or befuddling terminology which so confuses me.

[waltr]

This is explained as simply as possible in the book : "Inside the Metal Detector".
It does take some math which is easy to do with a calculator or spreadsheet (Excel, etc).

[Tim]

Waltr it is easy for you to say that the math is easy to do, but that is not the case for many people without a tertiary or even completed secondary education. I have ITMD and have now read it twice. As our illustrious authors say, even with the mathematic ability real world results are often not accurate. Therefore it would be good to simply know whether a cap or resistor value should be raised or lowered for a given situation. I am sure many here would innately know and do this, but other than caps in oscillator circuits, I have never seen a helpful reference to other relevant situations. Perhaps building the Raptor will help me understand this better.
I understand that some people who find mathematics easy will be contemptuous about my lateral approach, but that is hardly helpful to the gleaning of knowledge intended by forums such as this.
Perhaps it is just that I cannot see the forest for the trees. Oh well, I shall battle on in the hope that these elusive basics become clearer to me in time.