JPS61134123A - Bias oscillating circuit of tape recorder etc. - Google Patents

Abstract

PURPOSE:To maintain an oscillation output stably over a wide range of voltage by connecting a controlling transistor between the middle point of two oscillation coupling transistors constituting an oscillating circuit and the power source terminal, and connecting a rectifier circuit that detects the outlet level to an output terminal of the oscillating circuit. CONSTITUTION:When voltage V(o) of output terminal N of the oscillating circuit becomes lower than a set value, current in the rectifier circuit D decreases proportionally, and increases resistance between collector and emitter of a transistor 5. Thereby, voltage drop in a bias resistance R10 decreases and current that flows to the base of a controlling transistor Q increases, and voltage V(CE) between collector and emitter of Q becomes low and effective power source voltage becomes high and the oscillation output V(o) is returned to the set value. In the case where the V(o) becomes higher than the set value, current in the rectifier circuit D increases proportionally, and V(E) of the controlling transistor Q is made higher by reverse operation. The effective power source voltage of an oscillating circuit A is lowered, and consequently, the oscillation output V(o) is suppressed and returned to the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention relates to a bias oscillation circuit for tape recorders and the like, and more particularly to a bias oscillation circuit that stabilizes the output of the oscillation circuit.

Conventional technology: In order to stabilize the output of a bias oscillation circuit, conventionally, a power supply stabilization circuit was first combined with the power supply, then a bias switching circuit operated by a mechanical or electronic switch was connected, and these circuits The bias oscillation circuit was made to operate stably under the operating conditions. However, the oscillation output may change depending on the efficiency of the bias oscillation circuit.1. Furthermore, in the case of using a battery, it is actually difficult to stabilize the oscillation at low voltages, making it difficult to maintain stable oscillation.

Problems to be solved by the present invention: The technical idea of stabilizing the supply voltage, which has been practiced in the prior art, lacks the idea of operating the bias oscillation circuit using a practical effective power supply voltage as an operating condition. Similar to the benefit of solving the disadvantage of the prior art that the oscillation output varies depending on the efficiency of the bias oscillation circuit, the present invention solves this blind spot in the basic circuit concept.

Means 2 for Solving the Problem The technology of the present invention connects a control transistor Q between an intermediate point between oscillation coupling transistors 1 and 2 constituting an oscillation circuit and a power supply end, while
The bias oscillation circuit is configured such that a rectifier circuit for detecting the output level is connected to the output end of the oscillation circuit, and the control transistor Q is operated by the output of the rectifier circuit.

Effect: For the output level V (o) of the oscillation circuit, ■
(0) decreases, the resistance of the control transistor Q is lowered by a signal via the rectifier circuit, the effective power supply voltage of the oscillation circuit is increased (and the output level (0) is returned to the set value.The output level V (o ) becomes higher than the set value, the control voltage of the control transistor is lowered by a signal via the rectifier circuit so that the resistance of the control transistor Q increases, and this directly lowers the effective power supply voltage of the oscillation circuit to reach the set value. (2) Return to (0).The power supply always supplies an effective power supply voltage to the oscillation circuit to stabilize the oscillation output.This allows oscillation to occur in a wider voltage range than before.

Example: In the case of the oscillation circuit A shown in the drawing, a control transistor Q is connected in series between the midpoint M of the oscillation coupling transistor 1.2 and the negative power supply terminal ES2, and the positive terminal B of the power supply
This is an example in which the SI is connected to the primary side of the coil 3 of the oscillation circuit A. Application (load) circuit section B connected to this output terminal N
has recording heads H1, R2, and R3 of a tape recorder. R1-R6 are resistors, and C1-C3 are capacitors. Here, the rectifier circuit has a resistor R7 at the positive end of the output terminal N.
- Diode 4 - Capacitor C4 - Ground are connected in series to detect and smooth a part of the oscillation output. Capacitor C
Resistors R8 and R9 for adjusting oscillation intensity are connected in parallel to transistor 5, and the control end is connected to the midpoint between the two resistors.

A recording switch 6 and a control bias resistor RIO are connected between the control terminal of the control transistor Q and the power supply terminal ESI, and the operation of the transistor 5 is used like a variable resistor. A control transistor Q connected between the intermediate point M of the oscillation coupling transistor 1.2 and the power supply terminal ES2 operates in response to the output of the rectifier circuit.

When the voltage v(0) at the output terminal N of the oscillator circuit becomes lower than the set value, the current in the rectifier circuit decreases in proportion to this, increasing the collector-emitter resistance of the transistor 5, which causes the bias resistor R10 to The voltage drop in the control transistor Q decreases, the current flowing to the base of the control transistor Q increases, the collector-emitter voltage V (CE) of Q decreases, the effective power supply voltage of the oscillation circuit A increases, and the oscillation output ■(0) increases. Return to set value. ■When (0) becomes higher than the set value, the current in the rectifier circuit increases in proportion to this, and due to the reverse operation, the V (CE) of the control transistor Q increases, causing the effective power supply of the oscillation circuit A. The voltage is lowered, resulting in the oscillation output v
(0) to return to the set value.

When the present invention is applied to a bias oscillation circuit of a battery-powered tape recorder, stable oscillation can be produced even under conditions where conventional voltage stabilizing means against voltage increases and decreases cannot produce a stable voltage.

The combination of the control transistor Q provided between the oscillation circuit A and the power supply BS and the rectifier circuit connected to the output terminal N of the oscillation circuit A is not limited to this embodiment. The signal amount of the rectifier circuit is the oscillation output V (.

), and the circuit configuration in which the control transistor Q operates in response to this signal to stabilize V (o) at the set value can be appropriately selected from known techniques.

Effect 2: The control transistor Q is controlled by the output of the rectifier circuit corresponding to the oscillation output V (o) of the oscillation circuit A.
0) decreases, increase the effective power supply voltage of oscillation circuit A to return V (o) to the set value, and when V (o) increases, lower the same effective power supply voltage to set v (0). This eliminates the need for stabilizing the supply voltage, which was required in the past, and allows the oscillation output voltage to be switched freely regardless of the efficiency of the oscillation circuit, allowing for a wider voltage range than before. The oscillation output can be kept stable over the range.

[Brief explanation of drawings]

The drawing is a schematic circuit diagram showing one embodiment of the present invention. A: Oscillator circuit B: Application circuit D: Rectifier circuit Q: Control transistor ESI-E
S2: Power supply 1.2: Oscillation coupling transistor 5: Transistor

Claims (1)

[Claims] A control transistor Q is connected between the midpoint between the oscillation coupling transistors 1 and 2 constituting the oscillation circuit and the power supply terminal, while a rectifier circuit for detecting the output level is connected to the output terminal of the oscillation circuit. A bias oscillation circuit for a tape recorder, etc., characterized in that the control transistor Q is operated by the output of the circuit.