Digital Volt Ampere Meter

Description :

Even if the digital multimeter have dominated in a lot of applications, in the measurement, exist the need for existence of instruments of clue in various appliances, voltage and current, as in power supply or elsewhere. The circuits that give make this precisely the work, measure the voltage in terminal a circuit and the current that passes in his. The circuit does not present particular difficulties for somebody that has a small experience. The two circuits are the himself, with a small difference only in their input, when they have they measure voltage or current and in connection that concern decimal point [ dp ]. In the department of input IC1 and IC3, exist the CA3161E, that is a A/D Converter for 3-Digit Display. In the drive of Display IC2 and IC4, exist CA3161E, that is a BCD the Seven Segment Decoder/ Driver. As it appear in Fig.1, that concern the voltmeter in input [ + IN ], exist in series a what resistor R1 in combination with the R3 create a voltage divider. On the contrary in the Fig.2 that it concern the ampere meter, this resistor does not exist, because the circuit is connected differently, thus the current pass through the R5, creating a fall of voltage, in her terminal, proportional current that it pass from this. 

Source- http://circuit-zone.com/