. Electronic apparatus for biological research. Electronic apparatus and appliances; Biology -- Research. SOFT VALVES milliamps. Whilst they are therefore similar in principle to reference tubes, they are much larger and more robust affairs. To ensure that the tubes will strike we arrange them in order, with high resistances across the less refractory ones, and apply the same rule as for reference tubes, except that the voltage seen by the tubes is now not V^^ but K{RlKR + Rl)}- I R oâ^-^vvw-. ^i ^. R, Figure Figure If the string of stabihzer tubes has an incremental resistance Rf, the
. Electronic apparatus for biological research. Electronic apparatus and appliances; Biology -- Research. SOFT VALVES milliamps. Whilst they are therefore similar in principle to reference tubes, they are much larger and more robust affairs. To ensure that the tubes will strike we arrange them in order, with high resistances across the less refractory ones, and apply the same rule as for reference tubes, except that the voltage seen by the tubes is now not V^^ but K{RlKR + Rl)}- I R oâ^-^vvw-. ^i ^. R, Figure Figure If the string of stabihzer tubes has an incremental resistance Rf, then so far as the reduction of the effect of fluctuations is concerned the equivalent circuit is Figure We have now to consider two aspects of stabilizer performance. 'Forward' stabilization is the tendency of the arrangement to maintain V^ despite fluctuations in Kâ. 'Backward' stabilization is the ten- dency of the arrangement to maintain Vg despite fluctuations in i?^, that is, despite variations in load current. Clearly the forward stabilization is good if R^ or Rj^ are much smaller than R. Also the backward stabihzation is good if the impedance looking back towards the stabilizer from the load is low compared with the load resistance. Therefore for good all-round stabilization we need R and Ri^ large and R^ smafl. On putting in some figures it turns out that the design of stabihzer circuits is surprisingly com- plicated and may even be impossible. For, caUing the striking potential of the tube or string of tubes V^, we have: that they may just strike, F^ = K(Rl)I(Rl + R)- Also that once they have struck Fâ = /i? + V,. Eliminating R between these equations K- V. + ^i = VuRl or IRr V = V-ââ " ' IRr F. Looking at the denominator of this it is evident that if the striking voltage Vi is so high that it approaches IRj^ then the expression goes to infinity, which means that the tubes will not strike however high we make Fâ. The arrangement is probably intolerably in
Size: 1997px × 1251px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
