Multimeter is engaged in electrical, electronic and technical workers the necessary tools, which typically use a high block 9V, 15A, or 22.5V laminated battery. This battery is not only higher prices, but life is short, often change very uneconomical. Here are several uses for a small multimeter DC boost circuit, the circuit structure is simple, less components, circuit boards can be modified directly placed in the position of the battery meter in the stack instead.
Shown in the figure is a 22.5 V output voltage up to DC boost circuit can be used to replace the 22.5 V of the laminated battery.
It uses the multimeter in a 1.5V battery, operating current is 25mA, the output current of about 0.5mA, for the multimeter's high enough to block off. VT1 and VT2 circuit composed of complementary multivibrator, its oscillation frequency of approximately 2kHz. T is the step-up transformer, the primary is complementary multivibrator load, the secondary winding to boost the output a high pulse voltage. The voltage capacitor C2 through diode VD1 and became the DC high voltage rectifier filter, then through the resistor R3 and the voltage regulator VD2 output a more stable after the high voltage.
T transformer circuit used in transistor radios available 502 audio output transformer, the secondary as the primary step-up transformer, not the primary center tap, tap both ends of the secondary as a step-up transformer. If you can not find a suitable transformer, you can also use the radio input and output transformer silicon steel made, with a diameter of 0.25mm junior high strength magnet wire 110 turns around the secondary with a diameter of 0.21mm enamelled wire around the high-strength 520-turn . First-class rooms to add a layer of insulating paper, and note the end of the beginning of the secondary coil of the same name.
Structure shown is a very simple small DC booster can be used to replace the laminated 15V battery. The core components of a transformer circuit using a pocket-sized Yan Chaoqi T dedicated transformer. Circuit power consumption of about 40mA, the output voltage is 15V. If the multimeter 15V battery 1.5V battery positive and negative phase, only to figure 7-70 in VD1 (C1, VDZ polarity transfer over, so a-15V output voltage.
Shown is a DC voltage boost circuit. The circuit can be a boost to 1.5V battery 9V, 9V laminated battery to replace. Circuit load input current of less than 1.2mA, the conversion efficiency as high as 60%. The circuit from the oscillator circuit and the voltage regulator circuits, which VT1, VT2, C2 component oscillator, color code inductance L, inductor, VD2 for the rectifier diodes, C3 is the output filter capacitor, VT3, VD1, VD3, and R2 is stable output voltage regulator circuit. Output voltage is approximately equal to the value of VD3 regulator.
Shown is a use of 1.2V, 500mAh nickel cadmium batteries do power inverter circuit, the output voltage 9V, digital multimeter available for use. Figure in the transformer T in the ring to wear around the use of 15mm made of (parametric mapping components are marked people named in the power switch on digital multimeter.
As shown in the table is controlled digital inverter circuit. It does not require the establishment of a separate power switch or switches on the transformation of the table. The circuit has low power consumption, stable and reliable, does not affect the instrument accuracy and so on. Circuit transformer T is E3-type ferrite cores, each folded into the mouth to the corner of the post-processing shape, L2, including, L1 out. The inverter power supply, the battery current is about 70mA.