JPS586413B2 - Block King Hasshinki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in blocking oscillators.

A blocking oscillator is an oscillator whose vibration stops after half a wave due to a strong positive feedback effect.As a means of providing positive feedback, a feedback winding is wound around the transformer and the voltage generated in this feedback winding is used. ing.

In addition to this feedback winding, the transformer is wound with a primary winding and a secondary winding for taking out the output.

By the way, winding a feedback winding in addition to the primary and secondary windings in a transformer increases the number of terminals and requires a special transformer to be manufactured, which not only requires more man-hours and becomes expensive;
It has the disadvantage of being large.

For this reason, when constructing a blocking oscillator, the cost and space of the transformer is significant compared to other components.

If a transformer does not have a feedback winding and has only primary and secondary windings, the structure can be very simple and inexpensive.

It should be noted that in a blocking oscillator, it would be very convenient to use the blocking oscillator in a variety of applications if the stopping and regeneration of oscillation could be controlled by a very small signal.

The present invention has been made in view of these points, and by replacing the feedback winding of the transformer with a transistor, the feedback winding, which was an essential component of a blocking oscillator, is no longer necessary, and it is extremely inexpensive and compact. In addition to obtaining a blocking oscillator, the blocking oscillator is also capable of controlling stopping and regeneration of oscillation with a minute control signal.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 is an electrical connection diagram showing one embodiment of the present invention.

In FIG. 1, ET1 and ET2 are power supply terminals, and COM is a common potential point.

Voltages E1 and E2 are supplied from power supply boxes ET1 and ET2.

Note that the same power source may be used for ETI and ET2.

T is a transformer with a primary winding n1 and a secondary winding n2, TR
, Paderlington coupled driving transistor, TR
2 is a transistor that controls the base current of TR1, R5
, Rf are resistance elements, and RL is a load.

For the resistance element Rf, a relatively high resistance of, for example, about 2 MΩ is used.

The power supply terminal ET is connected to the collector electrode of the transistor TR1 via the primary winding n1 of the transformer T, and the power supply terminal ET
2 is connected to the collector electrode of the transistor TR2 via the resistive element Rb.

The emitter electrodes of transistors TR1 and TR2 are connected to a common potential point COM.

The base electrode of transistor TR1 is the base electrode of transistor TR2.
The base electrode of TR2 is connected to the collector electrode of TR1 via a resistor Rf.

The load RL is E connected to the secondary winding n2 of the transformer T.
Tc is a terminal to which a control signal EC is applied, and is connected to the base electrode of TR2.

In the blocking oscillator of the present invention having such a configuration and connection, the operation when the control signal input terminal ET is open will be described below with reference to the waveform diagram of FIG. 2.

In Figure 2, Figure A shows the waveform of the collector current Icl of the transistor TR1, Figure C shows the waveform of the collector voltage Vcl of TR1, and Figure C shows the waveform of the voltage CFS induced in the secondary winding n2 of the transformer T. In Figures A, C, and C, time t is plotted on the horizontal axis.

At time t0, voltage E1 is applied from power supply terminals ET1 and ET2.
, E2.

As a result, if, for example, the transistor TR1 becomes conductive and collector current Ic1 flows, the collector voltage Vcl of TR1 becomes the saturation voltage V between the collector and emitter of TR1, and the voltage across the primary winding n1 of the transformer T becomes ``A constant voltage represented by CES is applied.

Let the current flowing through the secondary winding n2 of the transformer T be ■, and the excitation current of the transformer T be Im, then the collector current of the transistor TR1 is.

It is expressed as the sum of the current value converted to the primary side of 1pIs (where n is the transformation ratio of the transformer T) and the exciting current Im.

The secondary current I, % primary side conversion 8/n is constant, but the excitation current Im increases with time t.

Therefore, the collector current Ic1 of the transistor TR1 gradually increases with time t, as shown in FIG. 2A.

When Ic1 increases to a predetermined value at point A at time t1, the core of transformer T first becomes saturated.

When the core is saturated, the resistance of the primary winding n1 loses its inductance and becomes only the pure resistance of the coil, so the collector current Ic1 begins to increase rapidly.

On the other hand, the base current b1 of the transistor TR1 is the voltage E
2, but the upper limit of this base current is limited by the value of E2 and resistor Rb.

Therefore, the collector current ■cl can increase infinitely,
When the current amplification times the base current 51 in TR1, it reaches a peak and reaches point B, the collector potential Vc of transistor TR1,
The increase in is applied to the base electrode of the transistor TR2 which is in the off state through the resistor Rf, turning this transistor into the on state and increasing the base current b2.

When the base current Ib2 increases, the collector current 2 of the transistor TR2 increases accordingly.

When Ic2 increases, the transistor TR increases by the amount of increase.
, and as a result, the collector current Ic1 of transistor TR1 further decreases.

Since the change in the magnetic flux in the transformer T must be continuous with respect to time, a current in the opposite direction is applied to the secondary winding n2 of the transformer T in order to prevent the change in the magnetic flux as the collector current Icl of the transistor TRp decreases. flows, and a voltage in the opposite direction is induced in the primary winding n1.

Therefore, the collector potential Vc1 of the transistor TR1 rises, and as described above, the collector current c1 of the transistor TR1 further decreases via the resistor Rf.

When the collector current c1 of the transistor TR1 decreases, the back electromotive force of the primary winding nl of the transformer T increases accordingly, causing the collector potential VC1 of the transistor TR1 to rise further.

Due to such a series of positive feedback effects, the transistor TR1 is rapidly turned off at time t2V7C, and the collector potential vc1 rapidly increases as shown at the beginning of FIG.

Even when the transistor TR1 is completely turned off, the energy stored in the core of the transformer iT is taken out by the secondary winding n2 of T and supplied to the load RL as a secondary current ■S.

Assuming that the inductance of the secondary winding n2 of the transformer T is L,
The secondary voltage VSoc decreases with a time constant as shown in Fig. 2C.

Then, the back electromotive force generated in the primary winding n1 of the transformer T, that is, the collector voltage Vc 1 of the transistor TR1
also decreases with a time constant as shown in Figure 2.

As the collector voltage Vc1 of the transistor TR1 decreases, the base current Ib2 and collector current Ic2 of the transistor TR2 decrease, and as a result, the base current b1 of the transistor TR1 starts to flow, and the collector current C1 of TR1 starts to flow again.

When the collector current Ic1 begins to flow, the potential of the collector potential Vcl of TR1 drops, and therefore the transistor TR2
The collector current Ic2 of TR1 decreases more and more, the base current ■bl of TR1 increases, and Ic1 further increases (time t3).

Due to this series of positive feedback effects, the transistor TR
The transistor TR1 turns on rapidly, returns to the operation at time t0, repeats turning on and off of the transistor TR1, and this system continues to oscillate at a specific frequency.

Note that the transistor TR1 in the circuit of FIG.
Darlington coupled transistors are used.

The reason why this transistor is made into a Darlington coupling is not only to increase the loop gain, but also to provide the following two effects.

That is, the first is that when transistor TR2 is on, TR1 is off, but when TR2 is on, the saturation voltage VCES between the collector and emitter of TR2 is
is usually 0.3-0.4v.

On the other hand, if transistor TR1 is a single transistor,
The voltage between the base and emitter for this transistor to start turning on is 0. It is about 4 V, but T
If R is made into a Darlington coupling, twice as many single transistors are required to make TR1 conductive.

Therefore, the first feature of Darlington-coupled transistor TR1 is that when TR2 is on, Darlington-coupled transistor TR1 is completely turned off.

Another advantage is that when transistor TR1 is fully turned on, its collector-emitter saturation voltage VBES is close to IV if it is a Darlington coupling.

For this reason, the transistor TR2 is not completely cut off, and the change in the collector current of this transistor TR1 is fed back to the transistor TR2 without a dead zone.

Although various features are produced by Darlington coupling the transistor TR1 in this manner, it is not always necessary to use a Darlington coupling of the transistor TR1 depending on how the circuit constants are selected.

Next, regarding the circuit shown in FIG. 1, the case of controlling oscillation stop and reproduction will be explained.

A resistor Rf with a relatively high value is inserted into the transistor TR2 in the oscillator of FIG. This system is made to oscillate by being amplified by three stages of transistors.

Therefore, if a positive control signal is continued to be applied from the control terminal ETc to the base electrode of the transistor TR2, the transistor TR1 will continue to be cut off and oscillation will stop.

Then, when the control signal is removed, oscillation immediately starts due to the above-described operation.

As explained above, in the present invention, a transformer having primary and secondary windings is used, and the driving transistor TR1 is connected to the primary winding of this transformer, and the transistor TR2 is connected to the connection point. The base electrode of the transistor TR1 is connected, and the base current of the transistor TR1 is controlled by the transistor TR2, which replaces the feedback winding of the conventional blocking oscillator, so that positive feedback is applied to the base electrode of the transistor TR1. Despite having a blocking effect, a simple two-winding transformer can be used as the transformer, since no feedback winding is required.

However, according to the present invention, a small blocking oscillator can be obtained at low cost.

Furthermore, when the purpose is to obtain power, conventional blocking oscillators with feedback windings often cause the primary current of the transformer to oscillate on the order of amperes.
Oscillation cannot be controlled unless the control current has a very large value.

On the other hand, in the blocking oscillator of the present invention,
Oscillation can be stopped and regenerated arbitrarily with a control signal of about several + uA.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram showing one embodiment of the blocking oscillator of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the oscillator shown in FIG. ET1, ET2...Power terminal, ETc...Control terminal,
TR, ... Darlington coupling transistor, TR2.
...transistor, T...transformer, Rb, Rf...grinding resistor, RL...load.

Claims (1)

[Claims] 1. A transformer having a primary winding connected to a power source at one end and a secondary winding connected to a load; a collector electrode connected to the other end of the primary winding of this transformer, and an emitter electrode connected to the other end of the primary winding; a driving transistor connected to a common, a first resistive element having one end connected to a power supply end and the other end connected to the base electrode of the driving transistor, and a collector electrode other than the first resistive element. a base current control transistor which is connected to the end of the drive transistor, has an emitter electrode connected to a common terminal, has a base electrode connected to the collector electrode of the drive transistor via a second resistance element, and controls the base current of the drive transistor; A blocking oscillator. 2 A transformer that has a primary winding connected to the power supply end at one end and a secondary winding connected to the load, a collector electrode connected to the other end of the primary winding of this transformer, and an emitter electrode connected to the common. a tenth resistance element having one end connected to a power supply terminal and the other end connected to the base electrode of the first resistance element, a collector electrode connected to the other end of the first resistance element, and an emitter electrode connected to the first resistance element; a base current control transistor which is connected to a common and whose base electrode is connected to the collector electrode of the drive transistor via a second resistive element to control the base current of the drive transistor; and this base current control transistor. A blocking oscillator comprising a control signal input terminal connected to a base electrode of the driving transistor and to which a control signal for controlling oscillation stop and regeneration of the driving transistor is applied.