SU58868A1 - Tube generator - Google Patents

Description

in 1938, Mitcham (USA) proposed a generator circuit stabilized according to a bridge circuit.

The main disadvantages of this scheme are:

one . The need to isolate one of the bridge diagonals from the ground, which leads to the need to introduce into the circuit two oscillatory circuits and two transformer connections, and also makes it difficult to use a circuit on short waves,

2. The need for a very low-power incandescent bulb with resistance that varies non-linearly with heat; The creation of such a bulb is very difficult.

The proposed circuit shown in FIG. 1 of the drawing, which is free from these drawbacks and differs from Mitcham's scheme in that feedback through quartz is carried out not according to the bridge scheme, but according to a parallel T-shaped scheme.

As shown by Tuttle (R. I. R. E. V. 28, No. 1, 1940) and others, such a T-shaped scheme allows to obtain complete neutralization, despite the presence of watt resistances in it.

The conditions for the complete balance of such a scheme are as follows:

2 Q - equality of zero components of both T-links

l.RiCi 0) 2 2 /., equality of watt components of both T-units.

In this case, only neutralization of components without neutralization is needed, while watt components should give some finite potential difference e across the load, a definable ratio: 1:

-E

R. :; -

 If

where | JL is the gain factor of the amplifier.

Save all the advantages of the Mitcham scheme, the proposed scheme is devoid of its main drawbacks, namely:

1. The input and output of the amplifier have a common ground terminal, which facilitates the operation of the circuit at short waves. The capacitance of the quartz plates relative to the ground does not disturb the balance of the circuit (the capacitance of the plate A is included in the impedance of the generator E, and the capacity of the plate B is included in C3). In addition, the presence of a common grounded clamp eliminates the need for inductive couplings, and this allows us to simplify the circuit, in particular, to make it entirely on the resistances without oscillatory circuits (Fig. 2).