WM6,
God operates as MONOCOIL, but created Adam and Eve (to operate as TX and RX :-)

WM6, I live in Plovdiv. In this town was established project Pulsediscriminator PD3200, the aim of which was to sell cheap kit amateur builders. I was not involved in this project and even I even not have this kit because I can not make changes (it is made in SMT). This project was commercialized in 2007. A few days ago I published the latest circuit diagram before commercialization. The designers of PD3200 now create radars.

I'm not involved in the design of any commercialized Bulgarian metal detector. According to members of the former (R) EMI group, I'm so incompetent as a designer, that I can be useful only as a spokesman. After whole two years I was doing the work of the spokesman, these experts judged that I am unfit also for this position because I am not a perfectionist, not studying historical experience, not try to learn English terminology in this area and explain things without details and drawings, which is not appropriate for dummies. However, I received much information from these experts. I understand that the most important is a block diagram of each design. It must be perfect.
Now I found that I was infected by their disease and gradually I convert myself into such a perfectionist. Bugs even if someone writes in forums lowercase instead UPPERCASE.
I'm looking for flaws in the circuit diagrams of very large companies and even started to find them. I have proposals to eliminate them and improve the design. As things go, maybe someday I will present my project. For now, I'm sure that my project will not use MONOCOIL.
Here is a reinvention of two coils made in 1927.

Hi mikebg,

I hope you are on right way with your project, no matter if you use mono, OO, OOO or DD design of coils at the end.

All coil designs has their strengths and weaknesses.

I prefer mono due of its lightweight and for many tens of shape that can be build and by its relative easy  managed by coil design parameters. By DD shape you are very limited in different design possibilities.

In field practice for me is very important that coil is as lightweight as possible to not get inflammation of elbow after only one hour of detecting. On whole day detecting this is most important advantage between comparable coils. And generaly speaking mono and DD coils are today on its characteristics quite comparable (decision which to use can be important only in few specific situations).

I have my own experience as buyer and owner of one well web-promoted Bulgarian detector. Ridiculous story (when I get time I will publish it whole on one forum). I buy detector from Rex company and got it from concurent Micron company (all those web BG companies are only virtual scam not real companies). In short about my Rex Delta6: hypersensitive design in air tests, but hyper-unstable on terrains too - practically useless no matter of settings. Hope you don't go this way.

Good luck with your, I hope, groundbreaking new MD design.