Magnetic Resonance Devices based on Don Smith Concepts

[Yucca]

@stprueAnother option is to get your hands on an old CRT computer monitor or small television that everyone is throwing away these days, the premise of a crt is that an electron beam is deflected by a magnetic field. A mosfet gate is voltage driven which can be used to drive the deflection coils. A mosfet/555 can be used to drive the horizontal deflection coils and a mosfet on the vertical deflection coils will convert a voltage potential to a proportional current in the coils. It is a cheap alternative if you are playing with HV fields which tend to destroy oscilloscopes.
Regards
AC

Lol, my first scope was using my black and white TV twenty odd years ago. I used the existing TV vertical drive circuit to drive horiz yolk coils at about 29KHz scan freq. I drove the vertical yolk coils from an audio amp. No trigger made it all but unusable but it was cool watching music on it. I actually installed a DPDT toggle switch and a jack socket so I could switch my TV to scope mode and play my radio or tape player through it.


Speaking of scopes and music, this is a very cool X/Y vector encoded demo being viewed on an analog scope:

http://www.youtube.com/watch?v=s1eNjUgaB-g

if you have a 2ch analog scope with X/Y mode then try it yourself by putting probes across your computers audio output. When you run it you can observe the clarity of your computers audio amp, mines pretty poor and muddy.

The youtube info text contains a link to the waveforms to use in FLAC or WAV format.

[flathunter]

I gotta respect you builders on OU.com.  Using the insides of a TV as a scope??  Now that really is hardcore, A Team style 

Keep up the good work!  I'm too busy for any more Tesla fun, but when i finally raise the cash to move into a place with some space for the little one as well as my T.Coil, i'll be joining you.  Till then I am following every word with great interest.....

[stprue]

Why not go back to your old school and talk to your Head of Physics?
You might be able to start up a dialogue, and maybe bring your
rig in and test it on their premises.

Alternatively, you could ring up the Group Chief Accountant of any very
large firm, possibly British Telecom, and ask them if they will give you
one (They say "Yes" more often than one would think):
British Telecommunications plc
81 Newgate Street
London
EC1A 7AJ
This number may not be right, but you should ask for the correct one:
Tel: 020 7356 4894 (international: +44 20 7356 4894)

Paul-R

p.s. I suggest the chief accountant because they often have a very boring
life, and your intervention may be the most fun they have had for years.

That's good info, thank you kindly!

[stprue]

@stprueAnother option is to get your hands on an old CRT computer monitor or small television that everyone is throwing away these days, the premise of a crt is that an electron beam is deflected by a magnetic field. A mosfet gate is voltage driven which can be used to drive the deflection coils. A mosfet/555 can be used to drive the horizontal deflection coils and a mosfet on the vertical deflection coils will convert a voltage potential to a proportional current in the coils. It is a cheap alternative if you are playing with HV fields which tend to destroy oscilloscopes.
Regards
AC

Doesn't sound to impossible to do!  thanks.

[Yucca]

@All,

I'm going to wind another 24 turn secondary identical to the one I've already wound and then join the two secondaries together to yield a 48 turn split coil. I will make the joiner be adjustable so I can try different coil spacings.

I've also realised that at these frequencies you need to keep wires straight and fairly rigid because movement of wires changes L and wires getting too close changes C and so it doesn't stay in tune.

@Peter, your build is looking nice and rigid just like Dons did, this is important for ease of tuning.

My new coil will also be mounted on its side and I will move the primary cap and gap onto the coil board so the connections between them and L1 stay the same. I will use single cored copper wire with PVC insulation, like used in house wiring.

Thinking more about Dons table top device: it may be in effect a 3 coil device. 1 primary coil and two identical 1:1 coupled secondaries. The magic might happen between the two secondaries as peter has been speculating already.

One thing that bothers me is that the only tuning point we see on Dons device is the slidable L1. To tune a device like this I would think we would need variable C1 to tune L1 to L2/L3. Don seemed to have hit the sweet spot with two standard value C1s and integer turn L1. Was he lucky? In these aircoils the Q is quite narrow and peaky.

The only thing that might make me less suspicious is if the secondary end variable  resistor to ground enables one to tune L2/L3 half wave resonance precisely? I don't know yet because I havent established half wave resonance yet with nodes on the ends and antinode in centre tap.

I have just noticed a few 1kV caps of different values on some TV boards I have shelved, and I will desolder them later today. They should be OK provided my primary gap is kept at say 0.5mm or less.

Also I've just realised my bridge diodes have a minimum response time of 100nS (for some reason I thought it was 10nS). So I'm thinking that the max freq sin I can rectify is 10MHz. That's worrying because the natural 0.25 wave resonance freq of my 24 turn coil is about 16MHz, that means half wave resonance of a similar 48 turn coil would also be about 16MHz. Will faster diodes be needed? maybe.