Next connect one post of the .0007 mfd. condenser with one of the terminals of the detector filament; then connect the other post of this condenser with one post of the .0005 mfd. variable condenser and the other post of this with the grid of the detector, then shunt the megohm grid leak around the latter condenser.

The parts you need for this set include: one variocoupler; one .001 microfarad variable condenser; one .0005 microfarad variable condenser; one .0007 microfarad variable condenser; one 2 megohm grid leak; one vacuum tube detector; one 6 volt A battery; one 6 ohm, 1-1/2 ampere rheostat; one 200 ohm potentiometer; one 22-1/2 volt B battery; one .001 microfarad fixed condenser, one pair of 2,000 ohm headphones, and a variometer.

Now connect one end of the secondary coil, or rotor, to one post of a .0007 mfd. variable condenser, the other post of this to one end of the grid coil and the other end of this with the remaining end of the rotor of the variocoupler.

The parts you need for this set include: one variocoupler; one .001 microfarad variable condenser; one .0005 microfarad variable condenser; one .0007 microfarad variable condenser; one 2 megohm grid leak; one vacuum tube detector; one 6 volt A battery; one 6 ohm, 1-1/2 ampere rheostat; one 200 ohm potentiometer; one 22-1/2 volt B battery; one .001 microfarad fixed condenser, one pair of 2,000 ohm headphones, and a variometer.

Next connect one post of the .0007 mfd. condenser with one of the terminals of the detector filament; then connect the other post of this condenser with one post of the .0005 mfd. variable condenser and the other post of this with the grid of the detector, then shunt the megohm grid leak around the latter condenser.

One ampere of current passing through an ordinary incandescent lamp will produce a light equal to ten candles, and I have shown that by simply moving this small flat spiral a current is induced in it from the earth's magnetic field equal to 0.0007 ampere.

Now connect one end of the secondary coil, or rotor, to one post of a .0007 mfd. variable condenser, the other post of this to one end of the grid coil and the other end of this with the remaining end of the rotor of the variocoupler.