Nikola Tesla Books
Books written by or about Nikola Tesla
Colorado Springs
Sept. 1, 1899
Various ways of connecting instruments on receiving station experimented with and considered as to their merits:
Diagram 1. illustrates one of the earlier dispositions involving the principle, before described, of exciting by means of energy stored in the condenser. This principle has proved itself highly effective as it secures self-excitation and great magnification of an initial feeble effect. In Fig. 1 the defect is that no initial excitation of the condenser is provided for, which makes it difficult to employ a sensitive device of very high resistance which, for other reasons, is desirable. This fault is overcome in Fig. 2. by providing an additional battery B1 for charging initially the condenser and thereby exciting device a to the point of breaking down. Still in the latter diagram there is the inconvenience that the relay is traversed by a pulsating current during the time when device a is not excited.
The improvement illustrated in Diagram 3. does away with this drawback and this makes it possible to adjust the relay much better. Still the relay by its self-induction is apt to interfere with the vibration of the tuned secondary s. This consideration led to the modification illustrated in Diagram 4.
171
September 1-2
Returning to receiver problems, Tesla begins the analysis of the scheme shown in Fig. 1. With this circuit, he previously achieved good results in view of sensitivity by means of an efficient return link for the purpose of a "high increase of initial excitation''. With regard to series connection of battery and the sensitive device, the pre-excitation created by circuit T - C and which, via secondary S acts on sensitive device is not sufficient. That is why in Fig. 2 one more battery is added, which from this point of view improves the situation, because the pulsating current appears through relay R and therefore the relay in Fig. 3 is relocated to the secondary branch S and the sensitive device. Fig. 4 indicates an even better scheme by which the relay self-inductance influence is reduced by adjusted secondary circuit S.
Fig. 5 shows the best alternative with an aerial which Tesla calls "air line and capacitance" and with grounding by which the electromagnetic field does the excitation of the sensitive device. On September 2 he shows one more scheme and experiments with various voltages of batteries B and B1. He concludes that complete sensitive device excitation is achieved quickly (even at small excitation) if batteries B and B1 are connected so that their influence on capacitor C are added, and that the excitation is interrupted in the case of an opposite battery connection.
