Is This A Theremin?

TECHNICAL ALERT !  the following will probably be gobbldygook to anyone without good (university level) knowledge of electronics.

"Resolution is 5 hz, not 5 khz. Oops......" - W0ttm

5Hz is not bad for a 80s/90s kit .. LC oscillator and a ton of IC's !? .. 0.9 to 31MHz with 5Hz resolution - frequency set on thumbwheels ... quite acceptable!

My HP-3325A synthesisers (I have 2) have been some of the most useful kit I own - covers 1 uHz up to 20 MHz with resolution from 1 uHz (highest) to 1mHz (.001 Hz) at 20MHZ .. They are just incredible machines - and great for simulating theremin oscillators when developing mixers / waveshapers etc.. You may find the service manual for these useful, as it goes into great depth about how things work: http://cp.literature.agilent.com/litweb/pdf/03325-90002.pdf 

It may be that your LC oscillator is a VCO in a PLL system, with phase error CV controlling a varicap.

Sadly, these instruments are huge heavy bulky bits of kit.. Mostly I dont need better than 1Hz resolution, so a tiny PC driven board like this with 0 to 30Mhz coverage and worst case 0.3Hz resolution, is an ideal solution - two of these (at £5 each) would actually do most of what I use my big synthesisers for ..

Fred.

" Here he is with Alice and the Gryphon. " - Coalport.

I KNEW this was gonna get silly!

;-)

"I KNEW this was gonna get silly!" Fred.

Silly is good. Silly is my friend when I get home from a day at the salt mine.

"It may be that your LC oscillator is a VCO in a PLL system, with phase error CV controlling a varicap." Fred.

That's exactly what it is. It's one of the most useful tools I own.

"Silly is good. Silly is my friend" - w0ttm

Hmmm.. Perhaps "Silly" is the real reason we all congregate at TW.. The theremin must be the silliest musical instrument ever invented, and it therefore probably attracts silly people and serious(ly) silly people.

Then there are probably those who arent just silly, they are downright bonkers - but because they are bonkers they dont realise how silly they are -  and think of themselves as "serious" - (LOL) - but nonetheless, this sillyness is in them ("in their soul", if you like ;-) and they come under the spell of sillyether, and its intoxicating effect causes them to believe that the theremin is a serious instrument.

Then there are those (like me) who became addicted to sillyether, but the stuff became more difficult to obtain - the only reliable source being the TW dispensary, and they only dish up enough to keep one going for a day at best.. the craving starts after a few hours deprivation of the silly stuff  - we try to compensate by getting fixes of more dilute substances (like the elixir of Monty Python) or even, when desperate, by watching BBC "Horrible Histories" videos.

Sadly, nothing quite hits the spot like true sillyether - other sources of sillyness are, well, obviously "in yer face" silly - whereas true sillyether is subtle - like (to quote the one person who came, IMO, closest to subtle sillyness - the now sadly deceased , late great Douglas Adams) "A Pan-Galactic Gargleblaster" which is "like being hit on the head by a gold brick thinly coated with lemon".

Fred.