Garrett AT3

[Hannu]

I started yesterday to fix AT3. Coil is missing and data for it is needed.
Tx freq should be 5.5kHz?

This is test results with different coils i tried:
TX 6.0 mH ---> TX f=9.93kHz U=20V
TX 2.5 mH ---> TX f=14.96 kHz U=21.6V
TX 0.9 mH ---> TX f=25.2kHz U=8.9V

Unit was somehow working with tesoro coil but with big loss of sensitivity.

All info about coil will help....

[Hannu]

Deepseeker 5.5kHz R and L values would be big help.

[kt315]

seems you have to find a coil with more L value of TX...

Tesoro early Lobo DD
Rx 1,3 1.35mH 12 ohms
Tx 2,4 10mH 55 ohms

but by another way IMO you may increase capacitors values in TX part for decrease the freq to 5,5kHz....

[Hannu]

simulation

L=5.9mH and extra C=100n

[Hannu]

better picture. f=5.4khz

[Hannu]

LTSpice .asc file

[Davor]

You need to add Tx coil resistance, either by right-click on a coil, or simply add a resistor in series with coil. Spice will give you overly enthusiastic results with no series resistance in a coil.

[kt315]

yup. 22-24 ohm for tesoro coils with ~6mH TX.

[Hannu]

10mH 50ohm coil with 47n parallel capasitor gives f=5.3kHz and U = 15V (peak to peak) in simulation.

[Hannu]

Freedom 3 have same coil. Can somebody give data for that?

[Hannu]

It's working now. AT3 with crossfire supreme deepseeker coil. Had to pull out resistor and capasitor from coil.
Still need to test discrimination. It's giving nice bell sound with coins. Next step test outside of house.