Relationship between Series LC and Parallel LC

Your "rant" is really off topic and disturbing. We are a nonprofit organization, that does not sell anything. Our projects are Educational, OpenSource and DIY (we explain how to do), under Creative Commons License: 
www.theremino.com/en/contacts/copyrights

That said, there are manufacturers that produce our modules, according to our specifications. These manufacturers follow specific RoHs, etc. ... and assemble in accordance with the "sacred" rules of industrial production:
www.theremino.com/en/contacts/certifications

You're doing a great confusion between production and design! 

Production must use anti-static bracelets and all possible precautions. 

Instead us (designers), we do well to treat prototypes and industrially produced modules, with the greatest carelessness that we can, in order to identify weaknesses.

This is not carelessness on our part, but simply passion for the perfect design. We do not add components, because "they give you some help", but we try really to solve problems. Our modules have undergone every possible torture and are really very strong, if you believe it or not, it doesn't matter.

" We are a nonprofit organization, that does not sell anything. Our projects are Educational, "

You have no worries then - It is only the manufacturer and / or importer or distributor who are subject to EU quality regulations - it is their duty to comply with the directives and to insure that all design and manufacture of the product complies.

Every manufacturer I have dealt with has thrown this legal burden back to the design house (in fact, with every design house I have worked for in the UK, this is standard part of the design process - it is expected that the client will reguire full certification), insisting that they must present the technical compliance file and test-house results and/or obtain the certifications.(their responsibility then is limited to manufacturing the product in the way specified in the files submitted during the compliance procedure - if they change this, even the position of one wire, the change must be recorded and verified as not invalidating the compliance - the technical file also specifies the standards required for assembly, with regard to ESD etc)

If your manufacturers have not passed the responsibility back to you, then for most practical purposes you are off any potential "hook" ..

Oh, being non-profit or opensource makes absolutely no difference to your legal responsibility - or at least no difference to the legal responsibility of those manufacturing you designs - If someone manufactures and supplies a product, they are liable for any legal issues related to the product - its not nice, and scares the s*it out of me when I design safety critical stuff - but its right IMO.

Sorry - I never meant to be unpleasant - I just say things like they are, without any bullshit "padding" - One can then make informed choices which best serve your interests - And one will probably never manage to get everything "right" from a legal / red-tape perspective as a small operator, the costs of doing so fully would inhibit all small business - I make my choices, and as yet have nothing (of my own - tons of stuff being made by clients) in production - you made your choices, and are in production, and your products look extremely usefull for many applications.

And when (if) I do get my theremin related instruments into production, I will be forced to break the rules for the first batch - but I would be compliant on everything except RoHS, because I feel that all the directives except RoHS serve the customers interests and improve reliability - RoHS reduces reliability hugely (particularly if looking long term, say 10 years+) because the lead free solder degrades and cracks (already a large quantity of items are failing due to this after a couple of years), wheras lead stays "wet" for decades.. I may even risk using lead for full production, and only stop if I was forced to - because, to me, this aspect of RoHS serves no environmental purpose - there will be tons of equipment dumped a decade from now which could have been working many years longer if lead had been used - Ban lead on short-life products, fine.. But lead should be permitted in anything with an intended lifespan of >10 years.

Fred.

We might all have different approaches, due to different cultural, ethical, national, language, and whatever background. This may sometimes lead to discussions in which one side, although having the best intentions, might be perceived from the other side as offensive or provocative, or in the other extreme, as lenient and uninterested...

I'm sure there are absolutely no bad intentions in the minds of all participants in this discussion but I can sense a lot of adrenaline between the lines. I think that the current exchange of different points of view could be still more successful if everybody did some rhetoric and/or diplomatic filtering before clicking the "Post" button.

Hugh!

Thank you, Thierry..

But I think its more me who is the problem here -

I take things way to seriously - and have spent most of my life in tough engineering environments where one (and ones designs) are ripped apart mercilessly, and every action one takes MUST be examined to the tiniest detail..

And this is an aspect I have inherited - and its not really applicable to a hobbyist venue like TW!

So I come across as critical and unpleasant because I am critical and unpleasant (or at least present things in a way that causes discomfort) - My intention is not to be "hurtful" or "discouraging", but the concequence often is that, and worse. I do get passionate about silly things like quality, and am far less bothered by matters such as "elegance" - I prefer an ugly reliable board with neons soldered to it and some extra diodes etc over a neat SMD board without protection - even if the protection isnt absolutely required..

I am biased towards protecting against worst-case scenarios, and I admit that my designs include components others will see as wasteful. When I supply circuit boards, these have "needless" thermal resettable fuses and transorbs to protect for everything from overvoltage to reverse supply connection - probably about 10% of component cost is for "needless" stuff.  I need to accept that this is my personal choice and I have no "right" to impose this choice on anyone else. ( I hate designing for Chinese white-goods manufacturers, because they trim everything for minimum cost - "5c for a thermal fuse when we can just use a PCB track ???")

So sorry livio .. no personal attack intended.. And I do really admire your efforts and like the look of your products and software. If you look at my other postings you will see that its not just you I "go for" LOL ;-) I am a pain to everyone - and I will "attack" someone I respect and admire as vigourously (or more) than others.

Fred.

Your passion is admirable, it also happens to me sometimes to be nervous about technical issues, so I understand very well. No need to apologize, it is important to continue a friendly exchange of technical information, that forms the basis of this forum.

My turn!  ;-)

"2) No, not photon energy. I'm talking about the power needed to compete against atmospheric interferences and against high power broadcast emissions.

Short Waves - about 3 to 30MHz - Broadcast transmitters power is about 1kW to 10kW

Medium Waves - about 500KHz to 2MHz - powers in the range of 10 kW to 100kW

Long Waves - about 50 to 500KHz - powers of 100kW and up

Therefore, the power required to work undisturbed around 3 MHz is about ten times less, than that necessary at 300KHz."  - livio

Thank you for bringing up this topic livio!  I've thought about your response above and wanted to discuss it a bit.  See what you think:

For capacitance / playability reasons, Theremin "antennas" tend to be roughly the same length regardless of operating frequency.  This length then "sees" the various interfering wavelengths in the environment.  The closer the antenna length is to some multiple of a dipole length for the interfering wavelength, the more efficient it is at receiving the interference.  So, in some sense, all Theremin antennas, being the same geometry, are capable of being interfered with in the same way.

But things are likely worse when the Theremin resonant frequency is located near that of a strong broadcast signal.  So it seems prudent to stay away from large collections of strong signals, like the AM broadcast band. 

Should we build our Theremin to operate above the AM broadcast band or below?  If the broadcast power works out as you say above:

Above: broadcast power is 10 times weaker, but the Theremin rods are 10 times more efficient as antennas at these frequencies.

Below: broadcast power is 10 times stronger, but the Theremin rods are 10 times less efficient as antennas at these frequencies.

==============

I could be way off in my knowledge / reasoning, but if all else is equal (and it never is) I guess I'd aim for lower operating frequencies as emissions here are likely less regulated by the FCC and other agencies.  But a lower frequency tends to make inductor selection more problematic (self capacitance, temperature dependent ferrite cores, physical bulk, etc.)

You are right about the fact that at higher frequencies, the antennas are more efficient and so you can not really make a simple comparison, between 30 and 300 Volt.

In any case (due to the high Q-Factor ), our LC transforms the 3.3 Volt supply in 30 Volt peak to peak, making our oscillators, if not more immune, at least similar to those of a classical Theremin.

Which is the best band to use? Definitely not the Medium Waves.

Same story with the Long Waves, because there are present powerful radio broadcast transmitters and even more powerful transmitters for clock signals.

Below the Medium Waves you might think using the area between 300 KHz and 500 KHz, but this is not a really free transmissions area.

Instead, above Medium Waves, exists the band from 2 to 3 MHz, intentionally left free for nautical emergency transmissions.

Therefore, in my opinion, the only good choice is from about 2.7 MHz (when the hand is far away) to reach a minimum of 2.3 MHz, when the hand is close to the antenna.

"Instead, above Medium Waves, exists the band from 2 to 3 MHz, intentionally left free for nautical emergency transmissions."  - livio

I'm certainly no expert, and I hope you don't think I'm trying to argue with you, and the following only covers the US, but it seems to show lots of stuff in the 2-3 MHz region:

http://en.wikipedia.org/wiki/File:United_States_Frequency_Allocations_Chart_2011_-_The_Radio_Spectrum.pdf

As you indicated earlier, broadcast power will be a large factor, and I can't find anything on-line after a quick check that correlates transmit power, bands, etc.

Your map of frequencies link, is absolutely the best I've ever seen, thanks!

You can notice that from 2194 to 2495 and from 2505 to 2850 the map specifies only these voices: "mobile", "except aeronautical mobile" and "fixed"  This seems as "we have no precise info about"

-----------------------

The Standard radio frequency signal at 2500 KHz can be a problem, but we have not received it, on our tests, so it appears to be not so powerful.

-----------------------

It is difficult to get real info about these transmissions, but I can affirm that:

- On tests we made with a scanner, the band from 2 to 3 Mhz, appeared as unused.

- The band from 300 to 500 KHz was pretty busy.

If you have some radio amateur friend, he could try testing with a spectrum analyzer, we are very interested to know if in the USA the actual band usage, is different.

---------------------

Apart this, there is also another important consideration, the higher the frequency, higher are resolution and reaction speed.

"It is difficult to get real info about these transmissions, but I can affirm that:

- On tests we made with a scanner, the band from 2 to 3 Mhz, appeared as unused.

- The band from 300 to 500 KHz was pretty busy."  - livio

Interesting that you've looked into this personally.  I haven't done this myself, but probably should somehow.

What are your thoughts regarding emissions regulations?  I'm thinking (probably naively) that the FCC cares less about RF below 1 MHz than above?

It's a different world than when Theremin was doing his thing.  I wonder what regulations Moog Inc. is attempting to adhere to with the Theremini?