Nikola Tesla Books
Books written by or about Nikola Tesla
Colorado Springs
Aug. 2, 1899
New induction coil for portable apparatus, designed for investigation outside contained in box. Condenser method. Particulars: Secondary wound with wire No. 30, 32 layers plus one layer with thick cord. Turns 180 per layer. Total number of turns 5670. Least turn 1.25 x Ï = ? longest turn 3.5 Ï = ? average 2.125 x Ï = 6.675" or 17 cm. approx. for average length of one turn. Resistance of secondary 375 ohm. The dimensions of spool are as in sketch below.
The available length of coil 4" - 1/4 for two fibre flanges l = 3.75". The primary 50 turns as a coil before wound cord No. 20, Res = 0.51 ohm. The length of average turn 10.6" = 26.93 cm. Total length of wire in primary 530" = 1346.2 cm.
In connection with this there is to be used: a condenser to be adjusted, a charging coil experimental like wire to be adjusted to the condenser and break, a Thomas clockwork with wheel 180 teeth for break, the arbor carrying also a sensitive device so that same clockwork will serve for break and first sensitive device. A second sensitive device in secondary of oscillating transformer driven by another Thomas clockwork. This latter need not be used when self-exciting process with condenser employed. Relay brought from New York 996 ohms or thereabouts. This final.
Mantion bottles to be used compared with Champagne bottles. The latter would seem to be better suited. The tests showed as follows: Comparing 2 bottles of each kind filled as far as practicable and placed in tank with rock salt solution as in previous instances charged to same potential 356 volts approximately, the average of four readings was for: Maniton bottles 13° defl. for Champagne bottles 9.5° defl.
This gives: $! {{\text{Capacity of Maniton} \over \text{Capacity of Champagne}} = {130 \over 95}} $!
How by taking weight: $! {{\text{Weight of Maniton} \over \text{Weight of Champagne}} = {23 \over 36}} $!
These figures give a slight advantage to glass in Champagne bottle, but the latter was larger than the Maniton about 1/4" outside and contained a trifle over one quart. Furthermore, there is the usual hollow bottom (to deceive customers) and this increased the surface in the Champagne bottle. In view of this the conclusion is that the glass is not greatly different in respect to dielectric qualities in both the bottles. The Champagne bottle would unquestionably break down first because of hollow bottom, as it would be difficult to exclude the air. It would also be difficult to get the required number of such bottles in this quiet town. This compels use of Maniton.
134
August 2
A receiver of this type is mentioned in the entries of July 12th (the principle), July 28th (circuit diagram with two sensitive devices and relay), July 30th (in connection with earth waves). The transformer here has a frame similar to that of July 28th but with somewhat more turns. The sensitive device was described on July 21st.
Tesla often worked on several problems in parallel. Here for example we have entries concerning the receivers, the development of condensers for the primary of the big oscillator, and the power equation for a new configuration of the oscillator primary circuit. The condenser C1 in Fig. 2 protects the mains transformer against overload but has the drawback that it reduces the initial voltage on C2. Tesla's analysis refers to the case of two condensers in series, neglecting all transient phenomena. It may be that he was induced to think about protecting the mains transformer because of his doubts about the ability of the dielectric to stand the voltages which he intended to use.
August 2
July 12 (principal), July 28 (wiring schematic with the two sensitive devices and the relay}, July 30th (in relation with wave testing the ground). The present transformer has a similar core as the one of July 28 only now the number of turns is somewhat larger. The description of the sensitive device was given on July 21.
Tesla was frequently working at the same time on several problems. So here he first described about receivers, and then about capacitor construction for the primary of large oscillator. After that he considers the energy balance of one new connection of the oscillator primary circuit, Capacitor C1 on the Fig. 2 serves as a network transformer protection against a short circuit, but the disadvantage of it is that it reduces the initial potential on the primary capacitor C2. Tesla's analysis has been performed for the case of two capacitors while neglecting the transient events. It is possible that the capability in capacitor dielectric to withstand at the voltages he intended to use in further tests led him to decide that the protection of the network transformer was needed.
