Theremin Project for the Newbie

This Optermen Link was the first theremin project I designed nine years ago. I was trying to learn basic electronics.

Back to the super brite white LED experiment on the previous page. When I say I made a discovery, it means just that. It has nothing to do with the knowledge of the world masses because I came a day late, it has nothing to do with all the money I am going to make, it has nothing that I feel delusional secrecy about.

Fred said: "You produced a rational experiment (removing the LED) and showed that it was something other than the LED producing the RF signal..

But then you go and lose the plot - You WANT the LED to be producing RF! So despite showing that the LED isn’t producing RF, you continue.."

Wouldn’t it be wonderful if the budding theremin scientist could come to TW to share & ask questions?

In my LED post as usual I was not clear and the plot was lost in my explanation and I did not get an answer.

When I removed the LED I was using the LED as stand alone by itself. It is mounted in its own metal jacket that mimics a flashlight blub. Without taking that apart it is not possible to determine if the super brite white light LED generates the RF carrier at 700khz or that a switching power chip is embedded within that jacket enclosure. This LED bulb could be removed from the flashlight body and replaced with a standard incandescent bulb using two batteries. The flashlight itself is a very standard in design.

You WANT the LED to be producing RF! 

I am only observing not wanting anything to fit preconceived notions. 

All answers are simple when you have all answers

Is there a 1.5v switching power supply embedded in the LED jacket?  Yes/No  

I could go find the answer on the web but I am demonstrating to all the newbie’s drifting by the accessibility of the vast knowledge base found in the world of theremin. Actually this experiment has several dimensions. Some I may not invite but to the others I will not bite. I was surprised, more people visited this thread yesterday than I expected.

All newbies should place information about their self in the profile as you will receive a much better response from those of us that have been here for years. Also the Private Message feature at TW allows someone to send you a private email as only you will ever know your email address.

Christopher

Sorry Christopher, I misread / misunderstood your posting.

Ok, what you found from directly driving the LED is highly surprising to me - Now it might be that the LED has an inbuilt switcher, but I have never come across such a part -

To be honest, when I read the price ($3) I did wonder about the economics - thats a low price and to go to the trouble of fitting a switching booster rather than having an extra battery did seem strange..

So I dont know what you have detected.. You might have stumbled on a self oscillating LED, but I doubt it ;-) - More likely, I think, that the torch / leads / PSU / whatever are forming some tuned circuit or acting as an antenna which is "focussing" some radiated signal you arent seeing without this assembly being there..

But what do I know with certainty ? - Absolutely nothing!

Nonetheless, I sincerely apologise for my presumptions regarding your motivations, and particularly for my "You WANT the LED to be producing RF! ".

Fred.

Re: Oscillating LED?

"I bought this cheap $3 flash light (battery included) with a super bright LED but it only used one size D cell at 1.5v  Next to (10cm) an AM Radio it emits a clean AM RF carrier creating a clean blank spot on the AM dial. It would seem to me they have made it more cost effective to put a switching power chip inside the LED bulb than use an extra 1.5v cell. I removed the bulb for a second test and the same results. The RF also seemed to be found at various other frequencies across the AM dial. - Christopher

Had a quick look over white LED specs.. Cannot find one which has Vf lower than 2V .. So it would need to have more than 1.5V to glow..

Question - When you removed the LED, what voltage did you drive it from? - If you drove it directly from a 1.5V cell, then it must have a step-up circuit of some sort in the LED.

Adding a voltage doubler circuit into the LED - or possibly a HF square wave generator into a diode capacitor voltage tripler, well, unless its a fairly large LED, thats quite fancy! - not really my idea of "cost effective" but then it comes down to volume..

The harmonics would be the result of a non-sine switching waveform - dont know what frequency your lowest "blank spot" is, but that might not be the fundamental.

Fred.

As can be seen, usual booster circuits employing inductors might be a bit difficult to fit into a small LED!

http://electronics-diy.com/led-flashlight-1.5v.php

http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html

Actually Christopher, just re-reading your last post, I feel REALLY angry!

My apology for wrongly reading your question and for my unjustified assumption above stands, but IMO your "Is there a 1.5v switching power supply embedded in the LED jacket?  Yes/No " is just bloody rude!

If you REALLY wanted an answer, you could have opened the jacket and had a look! - OR you could simply have gone on-line and googled.. It would have been quicker than it took you to formulate and write the question, and a lot quicker than WASTING the time of anyone whos stupid enough to try to help you, and the cumulative time of everyone reading any replies.. Fine, IMO, to ask technical questions related in some way to theremins here - But not so fine to ask questions about other technical matters in the construction forum, particularly as the answer is available from 2 minutes googling and the question has no relevance to theremins!

Re the "Yes/No "" The answer is OBVIOUS and its YES!.. BUT, without actually having the item in ones hands, any YES/NO answer is presumptuous and unscientific.. and Yes/No answers teach the enquirer NOTHING! 

You DELIBERATELY mislead the direction of enquiry by saying you removed the "LED bulb" rather than detailing that you removed the whole front assembly - a critical detail you only chose to fill in in your last post.. I get so damn sick of my stupidity at believing ANYTHING you say!! - Your rubber bucket producing vocal formants for example - Yeah! - Pull the other one - You own a TM, I would bet that the sound went through the TM before it got shoved in the bucket!!! - Its real easy to post up one of your beloved samples, claim it was produced by some simple means, but not provide any REAL details.. You talk about everything being "detailed" on your website, but ITS NOT - except (perhaps) to your mysterious "chosen few".. You are utterly full of lies and BS!

"Wouldn’t it be wonderful if the budding theremin scientist could come to TW to share & ask questions?"

They CAN, and THEY DO, and THEY GET THE BEST ANSWERS HERE that THEY CAN GET ANYWHERE ON THE WEB!

But they dont get this from you! - All they get from you is deliberate distraction, deliberate ignorance, and often, I believe, dishonesty!

Fred.

Oh, once again I have learned the lesson - I wont be reading or replying to any post you make from now on, and I wont even look at any posts on any thread you start -

Moderators - please feel free to delete ALL my posts on this thread.. But if you choose to delete any, delete them all.

Your rubber bucket producing vocal formants for example - Yeah!

I think that me using bold lettering gets me into trouble. All of my claims are fun projects backed up by detailed webpages for ordinary adventurers to do things they find interesting.

I have several theremin tricks I could post at TW but I don't out of respect for people I call giants. As it requires work to achieve giant status in my circles.

As I have said before I have nothing to sell, that is why I share.

Another real question I had:

Has any theremin designer ever noticed that the theremin pitch antenna connected at a high impedance location off the tank circuit is more susceptible to external noise and interference like outside RF, that it is wise when ever possible to have and use a lower impedance antenna circuit connection?  I will not mention anything about that other stuff.

I have not seen this discussed before but one effect the high impedance connection creates is 50/60 Hz hum in the detected audio when your hand approaches the antenna from Null through the lowest notes. This is usually very slight but can be measured. I even saw this effect in a recent Hoffman recording, extremely subtle though.

Christopher

Chris:

OT, but please check your PM.

IHS ---- Dana

Hello Dana,

There is no PM I can find, with my new website and a new E-mail program we seem to have lost communication.

Oh great now what do I do?

Christopher

I figure you are away from home. Place the last 3 digits to your phone number after the seven and that should get you to our chat webpage with more info. You will have to paste this into the web address box at the top of this page.

http://www.oldtemecula.com/theremin/7

Christopher wrote: I have not seen this discussed before but one effect the high impedance connection creates is 50/60 Hz hum in the detected audio when your hand approaches the antenna from Null through the lowest notes. This is usually very slight but can be measured. I even saw this effect in a recent Hoffman recording, extremely subtle though.

Christopher, as you may know, I recently installed an RCA Radiola 106 Loudspeaker into Hoffman's instrument since it is clear from the inside fittings (which are unique to this type of speaker) that is what was originally in the instrument. This isn't surprising since that is the unit RCA provided with all its theremins.

Not knowing anything at all about these vintage speakers, I contacted the people at rcatheremin.com to find out how to refurbish the speaker, install it, and then check it for performance. These guys were very helpful, as always, and sent me a comprehensive guide to the 106, which included the following paragraph concerning the hum you hear on the recent recording.

"Audio test, listening also for possibly objectionable hum level. Raspy distortion would be related to cone alignment, etc., if the sound is otherwise relatively clean. There will be some light background hum -- there always was on these.  As they are, they're generally quite all right, especially as soon as you start playing -- the background noise level becomes all but unnoticeable."

Don,tknow if this will work. So will just say I am in Hospital. hEADING FOR surgery in a couple of hours.  Later............................. dana

PM not working so ill just post the above intended for Chris only. Sorry to screwuop this thread for the resr of you.                                 dana

Message Received,

You are in my prayers for a quick recovery my Dragonfly friend.

Christopher