JPH0145228Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply smoothing circuit used in various electronic devices, and particularly to the same circuit that is most suitable for supplying DC power to an amplifier.

In a conventional power supply smoothing circuit, as shown in Fig. 1, a rectified output from a rectifier circuit (not shown), that is, a non-smoothed voltage is applied to an input terminal 1, and a capacitor for a filter is applied when a power switch 2 is closed. 3 through the resistor 4, and when the capacitor 3 is charged until both ends reach a predetermined voltage, the transistor 5
is turned on, a stabilized and smoothed output voltage appears at the output terminal 6, and the load 7 is supplied with this output voltage.

However, as mentioned above, since the capacitor 3 is charged with a time constant determined by the resistor 4 and each value RoCo of the capacitor 3, the transistor 5 does not operate until the capacitor 3 is almost completely charged. Therefore, when the load 7 is an amplifier, there is a drawback that the amplification operation is delayed.

Therefore, the present invention provides a power supply smoothing circuit that eliminates the above-mentioned drawbacks, and will be described below with reference to the drawings.

FIG. 2 shows the power supply smoothing circuit of the present invention, where 8 is an input terminal, 9 is a power switch, 10 and 11 are bias resistors, 12 is a base resistor, 13 is a smoothing capacitor, 14 is a first transistor, and 15 is a first transistor. 2 is a transistor, 16 is an output terminal, and 17 is a load.

Next, to explain the operation of the circuit of the present invention, at the moment when the power switch 9 is closed, the smoothing capacitor 13
Since the charge at is zero, the potential at point B is equal to the ground potential. When the power switch 9 is closed, a non-smooth voltage of Vc.c. appears at the point A, the second transistor 15 is immediately turned on, and the base of the first transistor 14 rises accordingly. The first transistor 14 is turned on, and a voltage obtained by subtracting the voltage drop between the collector and emitter of the first transistor 14 (approximately equal to the saturation voltage) is generated at the output terminal 16.
Added to load 17.

A charging current flows through the smoothing capacitor 13 via the bias resistor 10, and when charging is completed, points A and B have almost the same potential, so the second transistor 15 is cut off, and the base of the first transistor 14 is cut off. A predetermined bias is applied to the bias resistor 10 and the base resistor 18, and the ripple included in the unsmoothed voltage applied to the input terminal 8 is removed by the bias resistor 10 and the smoothing capacitor 13, and the output The terminal 16 has
A smoothed output voltage appears, supplying the load 17 with a DC voltage.

As described above, according to the power supply smoothing circuit of the present invention, the delay in power supply to the load when the power switch is closed and the delay in the operation of the amplifier, etc. connected as a load, as in the conventional case, are completely eliminated. As soon as the second transistor is turned on, power can be supplied to the load.

As an example of the present invention, when the following values were used in FIG. 2, the intended purpose could be achieved.

R1=2.7KΩ R2=330Ω R3=10KΩ R4=2.7KΩ C = 100μF

[Brief explanation of the drawing]

FIG. 1 shows a conventional power supply smoothing circuit, and FIG. 2 shows the same circuit according to the present invention. Explanation of main figure numbers, 8...Input terminal, 9...Power switch, 10, 11...Bias resistor, 12...
...Base resistance, 13...Smoothing capacitor, 14...
...first transistor, 15...second transistor, 16...output terminal, 17...load.

Claims (1)

[Scope of utility model registration request] an input terminal to which a non-smoothed voltage is applied, a first transistor of one conductivity type whose collector and emitter are connected in series to the input terminal and the output terminal, and a transistor between the collector and base of the first transistor. a second transistor of the other conductivity type to which the collector and emitter are connected; a smoothing capacitor connected between the bases of the first transistor and the second transistor and the ground; and a non-smoothing capacitor connected to the input terminal. It consists of a power switch that outputs or cuts off a voltage, and a load connected to the output terminal, and when the power switch is closed, the smoothing capacitor controls the base of the second transistor to A power supply smoothing circuit characterized in that the first transistor is turned on at the same time as the second transistor is turned on, and power is supplied to the load.