Kapanadze Cousin - DALLY FREE ENERGY

[John.K1]

Hi Void. Thanks. It makes me sense now.

[TinselKoala]

Starcruiser, Dog-one, Void: the best posts I've seen in this thread in a while.

Nick, Tom, John: Pay attention to what these folks are saying!


A scope is very necessary for this kind of work. Sure, you can do it without a scope, but the scope, properly used, will bring great understanding.

The genuine Texas Instruments TL494 will work at much higher frequencies than it is rated for, especially if its outputs are used to drive an intermediate high impedance buffer stage before the power transistors. Like the way the logic is used, to provide pulse width control and some delay.

The single pulse method Void describes is easy to apply, you can even pulse the primary or a test loop with just a battery using a momentary contact. See the first scopeshot below, that I just  made from a system I'm working on. There is a 4 turn primary and a 400 turn secondary. I simply touched wires from a 9V battery momentarily to the primary (STIM, blue trace) and used an open scope probe lying next to the secondary to pick up that coil's resonant ringing (RESP, yellow trace). As you can see the cursor measurement gives a resonant frequency of 1.351 MHz for the arrangement. The primary's driver circuitry is still connected but not powered. The bottom of the secondary is connected to the driver transistor's Base as is normal. So this should be close to the actual resonant frequency of the device as used.  The scopeshot was made using the Single-Shot mode of the scope, triggering on the STIM (9v battery to primary coil) signal's falling edge.
The second scopeshot below was made while the apparatus is actually running, with the Blue trace now the Base signal. The Yellow trace is still from a non-connected open scope probe near the secondary coil. The actual frequency while running is a little higher than the frequency indicated by the single-pulse ringdown. 

[John.K1]

Tk,
Excellent info. Thank you.  I have one more question for you. May be you will be able to answer me.  My Tesla is partially Tapered. Has this any "extra" effect on its functionality?

[TinselKoala]

Tk,
Excellent info. Thank you.  I have one more question for you. May be you will be able to answer me.  My Tesla is partially Tapered. Has this any "extra" effect on its functionality?

I really don't know. I have seen "tapered" or even fully conical secondaries used in some old TCs but I can't help but noticing that all modern TCs that real enthusiasts are building all use cylindrical secondaries. My own feeling is that a tapered secondary is more trouble than it's probably worth, but as I say I really don't know. I do know that low-aspect-ratio secondaries (a low height:diameter ratio) seem to work best for me, but my goals in making TCs are probably different than yours.

The primary is another story. For a traditional spark-gap tesla coil you will often see inverted cone shapes or even flat pancake primaries; this is for several reasons. The top of the primary needs to be kept far enough away from the secondary that there is no chance of arcing between the coils; the coupling needs to be relatively loose so the secondary can ring freely between sparks; the self-inductance needs to be kept low, etc. But for solid-state TCs where the primary is lower voltage and is driven at the secondary's resonant frequency 1:1, the coupling can be greater for better power transfer and there is little chance of arcing to the secondary, so the primary is often wound directly on the secondary or with only a small gap, and is cylindrical.

[John.K1]

I would like to ask you for one more opinion.  I use my "Antenna" as acouple turnes of bare coper tube. Ruslan shows his "Antenna" as a thick wire with thick insulation. Antenna has  influence on the output frequency- I guess because its capacitance. Does make sense the thicker insulation reduce the self capacitance (capacitance between the turns?)  In my mind is an Idea to 3D print a support which will isolate the turns from each other but the coper tube will be open to normal vector of the inductor coil.  Would this help to reduce the effect of the frequency drop and to keep still enough of open air for its ionisation (or what ever is going on there   )?  Is number of turns important. I have 4 and I am thinking to reduce it to 2.

Thank you.