Fig. 156. Explanatory Drawing of Quenched Gap.
The number of disks required is governed by the voltage of the charging condenser. Generally speaking it is one section of .01-inch gap for each thousand volts delivered by the secondary of the transformer. It is very important to secure just the proper number of disks. If properly adjusted, the quenched gap will give one discharge for each alternation of the current and produce a musical tone.
The quenched gap is placed in the same position in the transmitting circuit as any other form of gap.
ROTARY GAPS.
Rotary gaps are divided into two general classes, the synchronous gap and the non-synchronous gap.
The former usually consists of one or more stationary electrodes and a rotating member made like a star wheel with projecting spokes. This rotary member is attached directly to the shaft of the alternator or motor generator and arranged so that a spoke always comes opposite a stationary member at the exact moment that the maximum of potential is obtained in the condenser. Such an arrangement permits one discharge for each alternation of the current and produces a pure musical note easily distinguished in the telephone receivers at a distant station.
In the non-synchronous rotary gap the wheel is driven at a high rate of speed without any regard to synchronism with the alternations of the current.
The rotary gap shown in Fig. 157 is of the non-synchronous type.
Fig. 157. Amco Rotary Gap.