TRIANGULAR WAVE GENERATORS 



or the other is conducting and if both consume the same current the potential 

 difference across the cathode resistor is quite steady {Figure 16.10). 



Eccles-Jordan circuits occur in designs of electrobiological interest by 

 Dickinson^ (time base), Attree^ (stimulator) and many others. 



HT + 



HT* 



_K_ 



Figure 16.9 



o 



HT+ 



Figure 16.10 



TRIANGULAR WAVE GENERATORS 



The most important use for triangular waves is the production of time bases 

 for cathode ray tube displays. Both electromagnetic and electrostatic methods 

 of cathode ray deflection are relevant to electrobiology, so we have to consider 

 generators of triangular waves of voltage, and triangular waves of current. 



Triangular voltage waves 



The basis of all triangular voltage wave production is the charging of a 

 capacitance by a constant or nearly constant current, for then we have 



F = 



c c 



At the end of the charging period the capacitance is rapidly discharged, 

 completing the waveform {Figure 16.11). Suitable sources of constant current 

 are the saturated diode or the pentode {Figure 16.12). The latter method is 

 adopted in the famous Puckle time-base generator^. The Puckle time base 

 has certain disadvantages which render it unsuited to electrophysiological 

 work, and it will not be discussed here. 



239 



