Joule Lamp

[Lynxsteam]

Increasing the number of winds lowered the current draw and the bulb got dimmer (sounds crazy huh).  Next, I need to chart the taps and current draw and graph out to see how this is working.  Thanks again Lynxsteam for the wonderful plans and vids that made this a relatively simple build.

Brad S   

I have also seen some weird things while tuning.  Normally if you increase the primary turns, secondary voltage should drop and amps should go up to compensate.  But there are some resonance points you will hit even with this closed circuit.  I think what happens is, even though the base isn't being biased as much the frequency is staying high and so are the voltage spikes.

Normally if you drop the number of primary turns, the resulting Voltage will be higher and so the amps it takes to do the work go down.  power = volts x amps = watts
As you load the circuit more the voltage returning to the base of the transistor goes down and so the transistor is turned on and off slower resulting in almost a shorted circuit between pulses.  Amps in this case will be high through the circuit.  If you put very little load on the circuit the frequency of oscillation can go very high and amps will drop because the transistor barely has time to send a burst of current (amps) through the primary.  With the CFLs the voltage at start may be 240 volts, quickly drops across the bulb to 40 v and amps might be only .100 amps =  4 watts. 
As you load the circuit, frequency slows and amps go up, volts go down.  Volts might only be 10 across the bulb x .400 amps = 4 watts
What you will see at the source battery is voltage will drop from 12.4 down to 12.20 and amp draw might only be .350 amps = 4.27 watts
The rest of the power ends up as heat and vibration.  Keeping wires short, using heavy gauge where possible, tight connections all help efficiency.

All that said, I have also seen the initial power draw be high and then with a wiggle of the primary the power draw goes way down while the bulb is bright.  This may be resonance and energy cycling back and forth.  Its a moving target and takes constant tuning to achieve.

[conradelektro]

hi folks, here is a video showing the non-modified 15 watt cfl lighting.
http://www.youtube.com/watch?v=ZlajB1bRU3w
peace love light
tyson

What I have seen doing my tests and in the many nice and instructive posts and videos:

Air core:

- high inaudible frequency (100 KHZ very big coils, 300 KHz smaller coils)
- it is difficult to draw more than a few Watts (may be up to 5 Watts, the inductance of air core coils is rather low)
- non-modified CFLs do not work (the bare tube has to be used), some non modified LED lamps do not work (this is probably due to the high frequency, some circuits in the 110V or 220V lamps are not built for frequencies far beyond 50 Hz or 60 Hz)

Ferrite core, iron core:

- low audible frequency (1 KHz to 6 KHz, the whine can be a problem)
- amp draw can be very high (in case many lamps are connected and the transistor has a heat sink, the inductance of ferrite core transformers is very high)
- non modified lamps work, even incandescent lamps

General features:

- the main tuning problem is the number of turns for primary and secondary (this has to be right to a certain degree otherwise the circuit will not oscillate)
- the second important factor is the supply voltage and there are "sweet spots", going lower can be an improvement
- a possible way of tuning is a variable resistor between the base of the transistor and the positive rail, but this seems to be of limited value, once "transformer" and supply voltage are correct, a high resistance (10K, 50K) may help to start oscillation when power is switched on
- the circuit adapts itself to a wide range of load (as long as the inductance of the "transformer" is sufficient to support the load)
- it may be that lamps driven with this circuit may not last as long as specified by the manufacturer for 110 V or 220 V (because some circuit components in the lamps may be stressed, there is probably no problem with bare bone CFL tubes)

My conclusion:

If one wants a lot of light (many and very bright lamps) a ferrite core transformer is the right choice (but the audible whine has to be controlled in some way, e.g. by dipping the transformer in a resin).

For one bare bones CFL tube a air core design might be a nice choice (mainly for the looks and the low cost).

Greetings, Conrad

[JouleSeeker]

Good work to record "anomalies" -- this is where the "new physics" or at least new understanding is likely to occur IMO:

I have also seen some weird things while tuning. Normally if you increase the primary turns, secondary voltage should drop and amps should go up to compensate.  But there are some resonance points you will hit even with this closed circuit.  I think what happens is, even though the base isn't being biased as much the frequency is staying high and so are the voltage spikes.

Normally if you drop the number of primary turns, the resulting Voltage will be higher and so the amps it takes to do the work go down.  power = volts x amps = watts
As you load the circuit more the voltage returning to the base of the transistor goes down and so the transistor is turned on and off slower resulting in almost a shorted circuit between pulses.  Amps in this case will be high through the circuit.  If you put very little load on the circuit the frequency of oscillation can go very high and amps will drop because the transistor barely has time to send a burst of current (amps) through the primary.  With the CFLs the voltage at start may be 240 volts, quickly drops across the bulb to 40 v and amps might be only .100 amps =  4 watts. 
As you load the circuit, frequency slows and amps go up, volts go down.  Volts might only be 10 across the bulb x .400 amps = 4 watts
What you will see at the source battery is voltage will drop from 12.4 down to 12.20 and amp draw might only be .350 amps = 4.27 watts
The rest of the power ends up as heat and vibration.  Keeping wires short, using heavy gauge where possible, tight connections all help efficiency.

All that said, I have also seen the initial power draw be high and then with a wiggle of the primary the power draw goes way down while the bulb is bright.  This may be resonance and energy cycling back and forth.  Its a moving target and takes constant tuning to achieve.

Nice summary, conrad.

Also, if indeed the coil operates in Tesla-resonance mode sometimes and in air-core transformer mode sometimes -- that is important!  (good question, Nerzh, and good response lynx!)

[Lynxsteam]

LaserSaber gave me a hint about using much heavier gauge on the primary.  He didn't give me any details as to why, but I will give it a try to see what difference it makes. 

Using the same 12" long LJL I videoed yesterday I am going to use 18 awg 264 turns on the secondary, 25 turns x 4 in parallel  12 awg stranded insulated wire on the primary.  Doing this the primary is solidly filled across the length, but in effect is only 25 turns, but 6 awg.  It also provides perfect spacing on the primary coil.

[b_rads]

In thinking about the use of stranded wire vs. solid wire, I found this information on Wikipedia:

Wiki - Wire

This is what it says:

"At high frequencies, current travels near the surface of the wire because of the skin effect, resulting in increased power loss in the wire. Stranded wire might seem to reduce this effect, since the total surface area of the strands is greater than the surface area of the equivalent solid wire, but ordinary stranded wire does not reduce the skin effect because all the strands are short-circuited together and behave as a single conductor. A stranded wire will have higher resistance than a solid wire of the same diameter because the cross-section of the stranded wire is not all copper, there are unavoidable gaps between the strands (this is the circle packing problem for circles within a circle). A stranded wire with the same cross-section of conductor as a solid wire is said to have the same equivalent gauge and is always a larger diameter. However, for many high-frequency applications, proximity effect is more severe than skin effect, and in some limited cases, simple stranded wire can reduce proximity effect. For better performance at high frequencies, litz wire, which has the individual strands insulated and twisted in special patterns, may be used."