REFERENCES 



by 3 stages of amplification in earthed emitter, of which two are acceptor- 

 tuned by negative feedback through parallel T's. The tuned stages select the 

 jR-component of the electrocardiogram, and pass it on to a distorting 

 transistor which, working with practically no forward bias, delivers a positive 

 pulse at the collector corresponding to the peak of each R wave. This is 

 used to trigger the transistor equivalent of a cathode-coupled flip-flop 

 (Figure 45.55). Pulses of standard size thus derived are used to charge a 



-7 5 V 



Figure 45.55 



capacitor via a buffer transistor. The capacitor is discharged by a meter, 

 whose reading is therefore proportional to the rate at which R waves arrive. 



Wolfendale, Morgan and Stephenson^^ have reviewed the use of transistors 

 as computing elements, and include a decade counting circuit. 



Blake and Eames^^ have described a frequency meter for the range to 

 100,000 counts per second. The count rate is indicated on a meter having a 

 linear scale. The device is sensitive to input pulses only 60 mV in amplitude, 

 corresponding to a current of 12 ^A. The accuracy claimed is ±1 per cent. 



REFERENCES 



1 Bardeen, J. and Brattain, W. H. Phys. Rev. 74 (1948) 230 



2 Cocking, W. T. Wireless World 61 (1955) 500 



3 Oakes, F. Wireless World 61 (1955) 164 



* Stuart- MoNTEiTH, G. Electron. Engng. 28 (1956) 544 



^ Jones, D. D. and Hilbourne, R. A. Transistor A.F. Amplifiers London; Iliffe 



« George, R. E. Proc. E.P.T.A. Vol 7, No. 4 



' PoTOK, M. H. N. and Wales, R. A. McF. Electron. Engng. 11 (1955) 344 



8 Johnson, G. Wireless World 61 (1955) 31 



9 Neale, D. M. and Oakes, F. Wireless World 62 (1956) 530 

 1" Fleming, L. Electronics 30 (1957) No. 1 



11 Moody, N. F. Electron. Engng. 28 (1956) 94 



12 SuTCLiFFE, H. Electron. Engng. 29 (1957) 140 



13 Burton, P. L. Electron. Engng. 29 (1957) 394 



14 Johnston, D. L. Wireless World 60 (1954) 518 



1^ Mullard Technical Communication 2 (1956) No. 17 



1^ Light, L. H. and Hooker, P. M. Proc. Instn. elect. Engrs. Pt. B, 102 (1955) 775 

 " Light, L. H. Wireless World 61 (1955) 582 



1^ Nambiah, K. p. P. and Boothroyd, A. R. Proc. Instn. elect. Engrs. Pt. B, 104 

 (1957) 293 



709 



