coil generator : tester of coils

[kt315]

i give some pics from russians. you see a resonance value of rx and tx.

[kt315]

certainly DB. only copy the layout in sprint-layout and do a hotdog. i will still check it and then will order the pcbs.

[dbanner]

Ahh! Thanks KT. Now I can make for myself. I am working on new project called Beach bug/Goldhunter @20khz. May need your expertise.

[kt315]

one layer

[kt315]

absolutely right DB. by chinese transistor tester http://www.geotech1.com/forums/showt...2-Chinese-toys
possibly to measure L C and F - connected to the generator the resonance.

[dbanner]

Either oscilloscope or frequency counter meter. Measure freq. Then calculate inductances of coil being measured using formula or resonance calculator app. Then you can tune coil for any detector by choosing correct value for capacitor.
Read the translated text for better explanation of how circuit works.

[MartyJ1963]

@dbanner,,,thanks for the clarification,,,I didn't notice there was another drawing posted that was different. Does the 'Output' connect to the oscilloscope?, thanks. Marty

[dbanner]

There seems to be a fault in the drawing in post #13,,,,one terminal of the 1n4148 (VD2) isn't connected to anything and on the schematic it goes to the 220nf (C4),,,,just wondered if anyone noticed this. Thanks, Marty

If you look closely you will see that it is connected to vd1 and to c4. The green trace is obscured by the component. look at post #18, click on jpeg image.

[MartyJ1963]

There seems to be a fault in the drawing in post #13,,,,one terminal of the 1n4148 (VD2) isn't connected to anything and on the schematic it goes to the 220nf (C3),,,,just wondered if anyone noticed this. Thanks, Marty

[dbanner]

Yes, of course.

[kt315]

That is good idea, different sockets to plug in different coils, very good. But there is one caveat, and that is what if coil has internal capacitor?

then do not connect outer capacitor.

[dbanner]

Maybe an option for a capacitor in series.

[dbanner]

That is why C1 of 50pF is ideal. I think. This will still allow device to oscillate even with a cap in coil housing. I am not sure.

[dbanner]

That is good idea, different sockets to plug in different coils, very good. But there is one caveat, and that is what if coil has internal capacitor?

[kt315]

thanks to google.

i will do single layer. you can make a box with the board, preamp and diggest of different sockets under different detectors. you get a device for testing
of any coil, as self made as manufactured.