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A condenser also has a reactance effect on an alternating current but different from an induction coil the lower the frequency the greater will be the reactance. For this reason both a filter reactor and filter condensers are used to smooth out the pulsating direct currents. In the chapters on Receptors you have been told how to build up high-grade sets.
But when the positive half of an alternating current is made to flow through a large inductance it acts like a large resistance as before and likewise smooths out the current, but none of its energy is wasted in heat and so a coil having a large inductance, which is called an inductive reactance, or just reactor for short, is used to smooth out, or filter, the alternating current after it has been changed into a pulsating direct current by the rectifier tubes.
You will observe: that the terminals of the power transformer secondary coil which develops 10 volts are connected to the filaments of the oscillator tubes; that the terminals of the other secondary coil which develops 10 volts are connected with the filaments of the rectifier tubes; that the terminals of the third secondary coil which develops 550 volts are connected with the plates of the rectifier tubes; that the pair of filter condensers are connected in parallel and these are connected to the mid-taps of the two filament secondary coils; that the reactance coil and the third filter condenser are connected together in series and these are shunted across the filter condensers, which are in parallel; and, finally, a lead connects the mid-tap of the 550-volt secondary coil of the power transformer with the connection between the reactor and the third filter condenser.
You can make this choke coil by winding about 275 turns of No. 28 B. and S. gauge cotton covered magnet wire on a spool 2 inches in diameter and 4 inches long. Give it a good coat of shellac varnish and let it dry thoroughly. The Plate and Grid Circuit Reactance Coils.
They have a capacitance of 1 mfd. and will stand 750 volts. These condensers cost about $2.00 each. The Filter Reactance Coil. It consists of a coil of wire wound on a soft iron core and has a large inductance, hence the capacitance of the filter condensers are proportionately smaller than where a small inductance is used which has been the general practice.
The filament terminal takes a current of 7.5 volts and this is supplied by another secondary coil of the transformer. This rectifier tube delivers a direct current of 20 watts at 350 volts. The price is $7.50. The Filter Condensers. These condensers are used in connection with the reactance coil to smooth out the pulsating direct current after it has passed through the rectifier tube.
You can make this choke coil by winding about 275 turns of No. 28 B. and S. gauge cotton covered magnet wire on a spool 2 inches in diameter and 4 inches long. Give it a good coat of shellac varnish and let it dry thoroughly. The Plate and Grid Circuit Reactance Coils.
When an alternating current flows through a coil of wire the reversals of the current set up a counter electromotive force in it which opposes, that is reacts, on the current, and the higher the frequency of the current the greater will be the reactance.
They have a capacitance of 1 mfd. and will stand 750 volts. These condensers cost about $2.00 each. The Filter Reactance Coil. It consists of a coil of wire wound on a soft iron core and has a large inductance, hence the capacitance of the filter condensers are proportionately smaller than where a small inductance is used which has been the general practice.
The pulsating direct currents are then passed through a filtering reactance coil, called a reactor, and one or more condensers, and these smooth them out until they approximate a continuous direct current.
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