Housed in a former warehouse in Boeslunde near Slagelse, Denmark. Here you can see some of the Experimentarium's most spectacular objects. Drag the mouse over one of the five items in the illustration and left click to see more about Tesla coils, Jacob's Ladder, Mercury Rectifier and Marconi transmitter. 

You can e-mail Jens Aaløkke (OZ1GEO): radiosus@mail.dk

Mercury Rectifier

3 PHASES 380 V INPUT

220 V DC OUTPUT 20 A

AEG GERMANY 1920

Mercury Rectifier (Photo: Mathias Dyhr, June 2008)

Mercury Rectifier (Photo: Mathias Dyhr, June 2008)

A mercury rectifier containing a pool of liquid mercury. The electrons ionizing the mercury vapor are emitted by a high temperature arc circulating on the surface of the pool. The quartz tube containing the 380 volts electrodes are bent 90^o so no direct flash over can occur.

The tube contains a ‘dipper’ for starting the tube. The ‘dipper’ is activated by an external electromagnet and only activated for start-up.

Two minor electrodes are used for pulling a few amps for keep-alive current in case there is no load on the 220 V side.

A total of seven electrodes penetrate the quartz glass envelope.

The unit contains load resistances and start-up circuit.

  See video clip with Mercury Rectifier (duration 02:11)

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Jacob's Ladder

IGNITION COIL POWERED

SPARK LENGTH 1.5 CM

Two ignition coils are driven in counter phase to produce ~50 kV.

The Jacob's Ladder is between two electrodes from an oil burner.

The repetition rate is 50 Hz.

The ignition coil is driven by condensator of 2 µF in series with a thyristor. When the thyristor is turned on, when the power voltage is at its peak of 311 V an oscillation with a natural frequency of approx 8 kHz is started (a bypass diode is provided for the thyristor).

The high voltage secondary has the same natural frequency and

an optimum high voltage is obtained.

See video clip with Jacob's Ladder (duration 01:14)

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Marconi type transmitter

TYPE AT1000 VI

1 kW 500-3000 METERS

TUBE COMPARTMENT

SRA SVENSKA RADIOAKTIEBOLAGET 1923

JAAP 2008 (ANTENNA PART)

Marconi Type Transmitter

Closer look

Rear side

The unit has been used in a large Atlantic damper in the 1920’ths.

The tube compartment contains three Marconi tubes, two rectifiers and one self oscillating power triode. Original 2 pcs MRO6 and a MT2B were fitted. But as these are not available this unit is fitted with 2 pcs MRO4 and a MT4B. They are slightly smaller tubes. The original tube holders did not exist, so new substitutes are in place. The tubes are heated from a 500 Hz, 500 W supply and the original anode supply of 12 kV has been reduced to a modest 5 kV powered by another 500 Hz, 300 W supply in order to give 1000 Hz modulated CW transmissions.

The tuning unit was placed in the table and on the wall in the ships radio room is not salvaged. A substitute coil from a M. P. Pedersen transmitter from 1960 is used. The grid condenser is of the 10 kV type. The antenna coil is the Tesla coil no.1, frequency of resonance in 660 kHz. The top hat is connected to the coil through neon glow lamps which lights brilliantly during transmissions. The keying is done by a SSR in the 500 Hz supply and relay contact in the cathode connection of the tube. Power emitted 100-200 W.

See video clip with Marconi Type Transmitter (duration 02:58)

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Tesla Coil No. 2

TORUS Dy = 30 CM

COIL DIAMETER = 10 CM

SPARK LENGTH 0.75 METER

PEAK POWER 10 MW

FRES 540 kHz

Tesla Coil No. 2. Peak power is 10 MW. This is a time lapse photo, so there are several discharges in this photograph

Tesla Coil No. 2. Discharges to a grounded rod. This is a time lapse photo, so there are several discharges in this photograph

Tesla Coil No. 2

Power supplied by 6 pcs Oil burner trafos in a symmetrical set up. The condensers in the primary circuit is very large e.g. 8 pcs 12.5 nF. As consequence the primary coil consist of only 2 windings.

The peak power stored in the condenser is then very large as one should think this will give a spectacular show, but that is not the case.

The repetition rate is what gives the best spark length. Also provided a variac for adjustments of spark length.

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Largest Tesla Coil (No. 5)

TORUS Dy = 40 CM

Spark length 1.2 m

PEAK POWER 20 MW

Traditional TC made by Jens Aaløkke 2002 (Tesla Coil No. 5). Spark length: 1.2 m (4 feet),  peak power is 20 MW. This is a time lapse photo, so there are several discharges in this photograph

Tesla Coil No. 5. This is a time lapse photo, so there are several discharges in this photograph

Tesla Coil No. 5. Discharges to a grounded  rod. This is a time lapse photo, so there are several discharges in this photograph

Tesla Coil No. 5

Traditional TC with one layer coil on an 8” clear plastic tube.

Wire thickness 0.5 mm. Resonance frequency 500 kHz. Power supply made of 10 pcs Oil burner Ignition Trafos. In Europe these OIT’s are symmetric and the condenser in the spark transmitter is spilt into two in series with the coil and spark gap. Heavy wire is used for the primary. Built in variac for demonstrations with low power.

As the spark gap is fixed higher settings of the variac gives not a higher peak power, but a higher repetition rate – and only at this high rate the wanted spectacular long lightning can be experienced.  

Jens Aaløkke presents Tesla Coil No. 5 (left) and Tesla Coil No. 2 (right)  (Photo: Mathias Dyhr, June, 2008)

See video clip with my largest Tesla Coils (duration 02:53)

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