This high voltage lifter was developed for a public display. It has custom argon tubes for the upright high voltage wire supports. In addition it has small neon indicator globes at the corners of the lifter itself. Very impressive at night. Not really a high flier however due to the reduced voltage available after the argons plus the added weight of the small neon tubes which were later removed.
“Continue reading” for more details and 10 photos.

One further feature is the “Crash land” button. This uses a motorized switch to short circuit the power supply. This causes a loud and bright spark visible low down between the upright argons above.  The tall argons flash and the lifter loses power and falls. Kids (of all ages) love this one.

I have measurements of the plain vanilla lifter (i.e. no attached neon’s) which is a 30 cm triangle. This jumps up very smartly to its tether limit at 2 feet.

Input 24 V 0.80 A = 19 W
Output (measured after argons).
no load (argons only but no wires to lifter) ?30 kV 100 uA
plus HV Meter (100 uA FSD movement) 28 kV 130 uA = 3.6 W
plus lifter (no dropping resistor) 22 kV 400 uA = 8.8 W
Threshold for lift is 14 kV.

Hence net current is around 270 uA and net power used by lifter is around 5 W.
The argon tubes drop about 500 V each with the load of the lifter i.e. about 1 kV is lost. (but gain about 50 kV of coolness)
My lifter, give or take, uses 5 W to lift its 3 g (= 0.6 g/W).

This neat little helicopter weighs about 2500 kG, and lifts a further 2500 kg using 1 MW.
Proportionately 1MW would lift 600 kg with my lifter specs. Only about 1/4 that needed to achieve lift of the helicopter. One wonders if technology can’t offer something more efficient than my triangular lifter though. I have a few ideas …..

This is the power supply setup using a 30 kV DC regulated supply from a 24 V transformer and a small PWM (pulse width modulated) controller. This will be used for the public display lifter soon to be completed. It does not like repeated short circuits (and tends to blow the 2N3055 drivers) but this has been fixed by using a series resistance (12 kohm 5 W plus 15 kohm 5 W in series). This weakens the “Crash landing” spark which then had to be boosted with a 570 pF 40 kV doorknob capacitor.

 The upper photo above is a sunset shot and the lower photo shows a view between the argon tubes. I have highlighted the lifter separately. With this shot you can see the range of vibration of the first order harmonic of the closest wire which is about 1 inch in amplitude. If the tension is a little higher or humidity a bit less, this changes to a second order harmonic with a node in the middle. I guess this would be preferred as excursion is less, however the lift will be more as the wire gets closer and if there is an inverse square law then it may even be helpful.
My balsa supports started to track sparks and carbonize as the humidity picked up this evening. This is a prelude to a crash and burn. In desperation I used a light oil spray on the balsa supporting the upper wire which seems to have worked fine.

This shows the transparent control panel exposing the electronics of the PWM. The two controls are a red “Crash landing” control and a rotary “Soft landing” control. The right picture shows the lifter in the acrylic display during testing.
I am concerned by the radio frequency interference on both AM (~1 Mhz) and FM (~100 Mhz). There is no problem open circuit and the DC HV wire is shielded up to the upright argon tubes which serve as supports for the HV wire. Shorting the argon tubes does not seem to make a difference. I have tried a ferrite cored coil in series with the active lead with and without a resistor (330 K) although the latter does decrease performance. The sealed 30 kV HV unit is driven by a switch mode supply. This supply is giving minimal RF interference as a whine which I think I have fixed by putting a suppression circuit in the 24 VDC line. Some of the RF was corrected with a better connection to the 2×2 ft ground plane. Unfortunately correcting the RF at its presumed source, the corona from the upper wires, is not feasible due to weight constraints. I recently had to display the lifter within a few feet of a large plasma display monitor fortunately without problems. Interestingly, in the final version of the lifter, I did not remove the enamel from the support wires which means that they are a lot less agitated and give a lot less RF interference. I have also wound the support wires into a loosely spaced coil of about 10 turns around the last 6 inches of the argons to try to help block RF but I am uncertain if it helps.
The lifter was installed Nov 5th 2004 at the Gravity Discovery Centre in a 1.5 m square acrylic enclosure. This is the public interface to the gravity wave detector under development here in Western Australia. Still running in May 2012 with periodic replacements of the lifter and repair of fractured and oxidized wires.

The left picture shows the display poster. The right picture shows the full installation running. It has to be public proof and withstand lots of ‘crash landings’ from about 18 inches. The balsa frame is hot glued and also has some reinforcement at the point of impact. The support cotton threads have been upgraded to string from a small kite which is light and very strong. The display is lit by small arrays of lights with 8 high intensity LED’s each with green, blue and purple coming from different directions. The “soft landing” switch controls the power to the HV supply and is spring loaded to return to the up position. It is a challenge to get a truly soft landing and is nicely interactive in this way.

A demonstration by the Sylvia from the GDS,  practising her controlled flying.

Above shows some design modifications in response to problems developing during the first 12 months it has been on display. Wire fracturing was a frequent problem as the wires are vibrating for 8 hours per day. I have now used some fine Litz wire which has 7 strands plus a strengthening fibre and is really strong and should be much more resistant to fatigue fracture. (donated by Bert Poole)
The other problem I have with long term lifters is HV creep and charring of the balsa supports. I hope to deal with this with the nylon line support shown above that gives about 1 inch extra distance of the wire to the Balsa upright with a mild penalty in geometry as the top wire is now not vertically above the aluminium skirt.

An answer to a query about a museum lifter:

Related pages

Lifters All lifter topics
Lifter 80 kV High powered lifter

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Photo Date:   Nov 5, 2004