Voltage Controlled Blocking Oscillator (VCBO) and Its Application to Instrumentation and Nerve Models

Abstract

The condition for a feedback oscillator to have a blocking oscillation is found by using a model which consists of a harmonic system and a relaxation system. When the oscillator is in the condition to have the blocking oscillation, we have two types of oscillation modes: the ac pulse type and the dc pulse type. It is shown experimentally that the dc pulse type blocking oscillation is a degeneration of the harmonic system in the ac pulse type.
A theoretical and experimental result on the characteristic of the pulse repetition frequency vs. control voltage shows a good linearity in both the ac pulse type and the dc pulse type, which is the characteristic of the voltage controlled blocking oscillator (VCBO).
In the application of the ac pulse type VCBO, the author shows a simple telemetry transmitter for turbidity measurement by connecting a photocell to the input of the VCBO. The linearity, the voltage and the temperature dependency and the efficiency in this system are discussed, and they are shown to be sufficient for practical use. As another special application, the author proposes a digitally controllable VCBO, which can be obtained making use of a phenomenon in the middle mode between ac and dc pulse type.
Finally, some fundamental nerve models using a dc pulse type VCBO are described. An essential part of this model is the nerve cell which has multiple input terminals. The author investigates a threshold characteristic of the cell model, a visual perceptual model, a principal circuit of an inhibitory coupling and its characteristics, a maximum input selecting network, and a model of synaptic coupling.