Electronics for Theremins (1)

Great blog! Why no folks on tho? Thanks Fred.

This is related to a discussion on TW http://www.thereminworld.com/Forums/T/28866/keep-getting-weird-tones-while-recording?last=True

I found this crude test oscillator I built years ago to test SRF of inductors -

This is based on the EM theremin design by Bob Moog - It is a wonderfully reliable oscillator, and clipping an inductor between +Vout and TST one will usually get oscillations at aproximately the SRF of the inductor.

I put the transistors in sockets, as it is possible to blow them up if one connects something stupid - I also put sockets to allow a capacitor to be connected across the inductor.

A simple, basic but useful piece of kit for theremin developers.

Layout on 0.1" pad board:

Pads G1 and G2 are ground, VP1 is STABLE +12V, VN1 is STABLE -12V, Out is to 'scope / frequency counter, VP2 is +V supply to inductor, TST is to other side of inductor. Note that the TST lead is an "antenna" - it needs to be short.. The OUT signal will be low level unless into a high-Z input - the 100k is in series to reduce the effect of the measuring instrument, but this isnt ideal.

Layouts viewed from component side (top).

Pads shown:

This posting is a response to several email requests from people who have a problem understanding coil windings, particularly with regard to phase relationships. Below the phase dots are shown for a coil / transformer, and the equivalent schematic diagram given - together with calculations.

An online calculator is available from Pace Magnetics here: http://powermagnetics.co.uk/calculator.html

Following are some photos showing construction on pad board. This is a quick way to produce fast prototypes - Layout is done on 0.1" grid, with 2 layers - Upper (component side) layer should have minimum tracks, and these should be straight to enable easy wiring.

The component overlay was transferred to the component side using toner transfer method.

THEREMIN GROUNDING:

Hi Fred,

You have my interest up on your past research.

As for the physical issues, you do what you can and keep on trying.

By now, most of my neighbors know its better not to ask what I am doing, it would only make them needlessly worry.  Besides, I haven't caused anyone any injury and I keep the noise down to a minimum, so most of them just don't care.

I am not so interested in focusing the lightning as I am in just pulling a level of sustained current from the atmosphere.  If my theory on the atmosphere is correct, you should be able to use the voltage potential between the ground and the air to pull down a steady stream of energy and convert it into a useful energy source.  However, I am a long way from getting to that level.  I am still just running experiments to verify my ideas.  That's when I found the Theremen and began assessing its value as an measurement instrument.

Anyway, it sounds like we both have had some interesting careers in technology.

I look forward to our future dialog,

DAB

Thanks Dab,

"as you slowly explore what you can now do after the injury."

- Yeah, not really an inspiring "exploration" 8-(

"About the time I get really active, the pain levels shoot up and I have to back off for a while."

It is so damn frustrating, isnt it! I have lived my life quite recklessly - been a diabetic since a kid, but always lived as if I wasnt one - my atitude was that if I lived by "the rules" life wouldnt be much fun, and if it wasnt fun, what was the point of living anyway ?! So yeah, I took my meds (well, without insulin, you cant live) but largely ignored all other advice and ignored the threat of complications.

"When the fun falls through and the rent comes due.." Is where I am now. But at 55 I havent fared badly - All the severe type 1 diabetics I knew of my age died years ago, despite having lived by the rule book and led (comparatively) boring lives as a result.

"The Theramen interests me due to the way it uses free space capacitance to change frequencies.  I am researching lightning and the distribution of the charge in the atmosphere.  I think there may be a way to measure the charge changes from the ground using a theramen like device, but it will be a while before I get anything built."

Most interesting -

I did about 3 months research into atmosphere charge phenomena - in particular, the charge distribution from the electrosphere to ground - it was part of several years of research into "free energy" devices which I undertook as a (well paid) commission. I also did theoretical evaluation of the possibility of collecting energy from discharge events - in particular, evaluating Tesla's claims (which proved to be unfounded and / or grossly exagerated) regarding the destructive power of "focussed" lightening (he claimed, I believe, that this energy could obliterate cities).

Somewhere I have some photos of the weird contraptions I built - one of them was a wire mesh dome on a pole which towered way above the buildings in my area, and I at times attached metal streamers to this, to measure ionization.. What surprised me is that in the months it was up, I never had a single enquiry from anyone about what I was doing! LOL

Fred.

Placing equalizing inductors in plastic tube and mounting them close to antenna:

Attachments:

Hi Fred,

Sorry to hear about your health problems, but being a disabled engineer, I can fully appreciate the effort it takes to recover as you slowly explore what you can now do after the injury.

Yes, I agree about E14, I have had a lot of fun reading about the projects and discussions and offering my small bit of knowledge. 

The Theramen interests me due to the way it uses free space capacitance to change frequencies.  I am researching lightning and the distribution of the charge in the atmosphere.  I think there may be a way to measure the charge changes from the ground using a theramen like device, but it will be a while before I get anything built.

I work slow and in fits and starts.  About the time I get really active, the pain levels shoot up and I have to back off for a while.

Meanwhile I hope you get better and revive the discussion on Theramens here at E14.

It looks like you have a fair number of people interested, including myself.

So take care of your health and keep on making.

DAB