VIII. BIOELECTRIC MEASUREMENTS 



257 



This is true, when tlie resistance ot i\w. source is ((uite^ low so an ap- 

 preciable current may be drawn from it. This is true in such devices 

 as the barrier layer photocell oi- the thermocouple. HeTe 1 iiv. will 

 produce a current of about 10 ~^" amp. through a high resistance gal- 



Fig. 9. 

 are: 



Electronically regulated power supply (see text p. 258) . The components 



Li 



L2 



Ti 



T2 



Ts 

 T4 

 T5 

 Ci 

 C2 

 C3 

 C4 

 C5 

 Ce 

 R. 



Power transformer: pri = 110 

 v., 60 cycles/sec; seci = 5 v. 

 at 6 amp.; sec2 = 860 v. at 

 450 amp. 



450 ma. filter choke 



5U4 



6L6 



VR-105-30 



VR-150-30 



6SF5 



lO^f. 1000 v., Dykanol 



8 fiL, 600 v., electrolytic 



8 /uf-, 400 v., electrolytic 



4 ixi., paper 



0.25 Mf., 150 V. 



0.25 /xf-, 200 V. 



50 fi, 1 w. 



R2 500 fi, 1 w. 



R3 Power resistor (use only if cur- 

 rent is over 250 ma.) = 

 150 



load (amp.) — 0.25 

 R4 5 megS2, 1 w. 

 R5 0.5 megi], 1 w. 

 Re 0.1 megJ2, 0.5 w. 

 R7 15,000 fl, 10 w. 

 Rg 10,000 n, lOw. 

 R9 0.15 megfi, 2 w. 

 Rio 0.10 megfi, 2 w. potential 

 Rii 0.05 megl^, 2 w. 

 A 0-500 milliammoter 



CTi connect to center tap of 6L6 



filament transformer 

 CT2 connect to center tap of 6SF5 



filament transformer 



vanometer, which will be easily registered if the galvanometer is quite 

 sensitive. As has been indicated, 1 nv. is well below the limit of 

 resolution of the best amplifier. Further, one does not need to worry 



