Some tips for all LRL (no dowsing) builders.

[ANDREAS]

Hi all.
After 25 years experiments i want inform you what you must need for better results if you want build a LRL

1. Schematics.
Have you a schematic for a LRL, you make it and don't work?
Try change some resistors or capacitors etc etc. The secret here is simple.
We have a balance between all sections. Every part has not same parts as schematic . In this case need via experiments find the real value for any part in practice.

2. Coils
Need high Q. Search on internet libraries about "how you can make coils with high Q"
Some real LRL need very very high Q. For it, search for tips or ask about this radio amateurs forums.
The first building coil is very difficult, but later is easy build one for you.

3. Coils housing
Don't use PVC or ABS. Plastics materilas produce static field. All materials for 3D printers has the same problem, except some special materials for special 3D printers. The solution for it use wood. Some wood don't work, because has a plastic color profil or plastic glue inside the wood . The best for amateurs is balsa, because has low price and you can work with it very easy.

4. Box -case
The standards commercial plastic electronics box don't work. For example you put a PCB inside a plastic box, after calibration and close this box you can see the device don't work. It's simple capacitance effect via plastic.
The plastic are perfect for eyes but very poor for a real LRL. Change with wood or polyester!!!.
Make experiments with materials wood. Some types are better or use polyester cases

5. Glue
Is very important. Some glues don't work, usually you can use wood-glue.
6. Batteries case.
Don't use external batteries case. Don't use external cable for connection power supply. Maybe is easy for you, but you have problem via ground effects via negative power supply. The best put inside the box the batteries, but remember you must calculate the place via experiments. This is important for working fine PCB without problems from battery-ies metal case

7. Displays, processors etc
You like use a display or you like use a processor for your project?
Bad choice!!!!!
Every display or processors has a clock work via a crysta etcl. This clock make a parasitic signal and preamplifiers etc cannot read a real external signal, but a modulation signal as mix.. Perfect signal for a osciloscope but scrap for your project
So, use only analog parts. Check every part, don't use exotic parts and forget every stage with microprocessor near your LRL circuits. Maybe some engineers believe this is not important or processor circuits has shield. This is a myth, because the detection signal are near clock frequencies

8. Signal from your hands etc.
If your LRL go near your hand in antenna or main box etc and you have alarm signal, you must be sure your LRL don't work. A real LRL must be detect only external signal or a signal only if you touch it.
Sometimes you believe your LRL you see have a alarm if you go near your hand on circuits. In practice circuits detect your handle hand
and the anguish produced by your hand near the target test.
Ofcourse if you go near a metal your LRL and you have alarm without stop , you must be sure don't work. A real LRL must be only one quick beep near the metal and then must be mute.

9. Ground and sky effect
You must find the best balance for reject this signals. Need time and many experiments for find this for regulation sensitivities every stage and best power supply for every one. Find this via experiments on your lab and tests on your external field.

Best Regards