calculate

[moimoitoi]

hello, I can not find how.

If I have a detector 14 khz, and I seen make a coil 11x9 "(this is an example).

How to calculate and check with a osciloscope?

thank you

[Silver Dollar]

Well you need more info. Use a meter and measure the inductance on the TX and RX to start.
There might be a cap in the coil too. What kind of detector is it?

[moimoitoi]

I want to do a dd coil for MX300 (12.8khz)

[Silver Dollar]

Well the easiest way to make a new coil is to use the specs on the old coil.
As I said measure the inductance of the TX and RX. Many times the TX has
a cap in parallel. You need to oscillate it to find the cap value.

Older designs used a tuned RX that was off frequency from the TX. If it is
like that you need to figure the frequency it was tuned to. Newer ones use
a series tuned RX, some are even tuned to the third harmonic. By opening the
case and tracing the firs few components the RX coil goes to you can see how
it is configured.

Sometimes someone else has already made a new coil for a detector and you
can just follow their info but I couldn't find anything in a short search.

[moimoitoi]

So I measure the old coil, and I repeated the same steps but with a size of my choice?

How to measure tx and rx without removing my coil?

thank you

[moimoitoi]

clarification: I seen make a DD coil

[Silver Dollar]

Is the cable permanently attached? If so you would need to open the unit and unsolder the wires.

Once you have a target inductance there are calculators to help determine the number of windings needed.

[moimoitoi]

ok to unsolder the wire

5 wire, which take the measure inductance?

thank you