1801 



mamier two parallel alternating resistances /^ and Z^ may l)e 



replaced by a single one ot the value — , 



Z, -4- z, 



H. We can also find other connections by i-eplacing all tlie alter- 

 nating resistances by their conjugate complex values. Indeed in this 

 case there is a set of ^'s conjugate complex to the former ^'s which 

 also satisfy (12) and (13) for a real value of p. In the case that 

 there are no mutual inductions in the circuit, this can be obtaine<l 

 by replacing every self-induction />/, by a capacity 6''/. and inversely, 

 such that Lk C'h = L'], Cj, ■= p^ If mutual inductiotis also occur this 

 simple substitution is no longer applicable ^). Besides in this case 

 the mutual induction must change its sign. This may be arrived at 

 by changing the terminals on the primary or the secondary side. 



On the ground of the above genei-al rules we may draw the 

 following conclusions with regard to the generative connections: 

 There are two types of connections: 



I. Those with direct coupling. Here the grid is immediately con- 

 nected to a point of the oscillation-circuit. 



II. Those with indirect coupling. Here the grid is coupled by 

 means of one or more mutual inductions with the anode-circuit. 



I. Direct coupling. 



The general type of these connections, to which they can all be 

 reduced according to rule A, is given by tig. 5. z^ = z\ -\- z" and 

 z^') are alternating-current-resistances; r and -?. have the same signi- 

 fication as in (10). 



The relations (12) and (13) change into: 



^1 -I- z- 



I r^ /r 



. (14) 



. (15) 



z^ + *, 

 By combination of (14) and (15) we get 



tt 



z, z. 



r ^' 



^1 -f- ^■. 



^1 ^ *a 



(16) 



Fig. 5. 



') (Note lo the English translation). Prof. Elias lias kindly pointed out to nie, 

 that in this case a wholly symmetrical substitution is obtained by changing the 

 mutual induction into a "mutual capacity" (two condensers telescoped into each 

 other). 



2) In the fig. denoted by gothic letters. 



