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Operating voltage: DC5V
Operating current: 35mA
Accuracy: ± 1mA
Measurement range: 0 ~ 2A
Outrange display: The first data 1 or -1
Display color: Red
Type: Not assembled kit
PCB Size: 70.6*39mm
Display Window Size: 51*24mm
Packing List:Name Specification Code Quantity Metal Film Resistor 0.1 ohm/2W R5 1 Metal Film Resistor 2K ohm R1,R9 2 Metal Film Resistor 56K ohm R2 1 Metal Film Resistor 1M ohm R6 1 Metal Film Resistor 100 ohm R3 1 Metal Film Resistor 270 ohm R10 1 Metal Film Resistor 20K ohm R8 1 Metal Film Resistor 47K ohm R7 1 Metal Film Resistor 100K ohm R4 1 Monolithic Capacitor 100pF C1 1 Monolithic Capacitor 0.1uF C8 1 Monolithic Capacitor 0.47uF C4 1 CBB Capacitor 0.1uF C2 1 CBB Capacitor 0.22uF C5 1 Polyester Capacitor 0.01uF C3 1 Electrolytic Capacitor 10uF/25V C6,C7 2 Diode IN4148 D1,D2,D3 3 Stabilivolt Diode ST5V1 ZD1 1 Triode C1815 Q1 1 Inductor 2.2mH L1 1 Digital Tube 1 bit Common Anode Red DS1-DS4 4 IC ICL7107 U1 1 IC TL431A U2 1 Potentiometer 3296 1K ohm VR1 1 IC Socket 40P U1 1 Connection Terminal 2P J2 1 Connection Terminal 301-2P J1 1 Power Wire 2P Single Head 1 PCB 70.6*39mm 1 Filter Board 1 1 Shell 79*43mm 1 Screw M1.7*6mm 4
AMM-TE ammeter is mainly composed of ICL7107, power circuit, reference voltage source,
input circuit and display circuit.
1. ICL7107 is a BCD output integral type A/D conversion chip, its internal includes ;linear amplification,
analog switch,oscillation,display driving etc.
2. Power circuit is divided into positive power and negative power; positive power is input by J2,C8 filtering;
negative is composed of R8,Q1,L1,C6,C7,D2,D3 and ZD1,and generate -5V voltage is input by chip 26th pin.
3. Reference voltage source is composed of R1,R2,VR1,R9 and U2;36-pin is reference voltage input pin;
adjust VR1 potentiometer to let 36-pin voltage be 100mV.
4. Input circuit is composed of J1,R5,R6 and C3.When the current of measured circuit passes through R5,
it will generate a voltage on R5;this voltage will be input to chip 31-pin through R6 current limiting
and be processed;C3 is input voltage filtering capacitor.
5. Display circuit is composed of DS1-DS4,D1,D4;4 digital tubes can be drived directly by the chip,
R10 is current limiting resistance of DS1-DS3 digital tubes decimal points.Finished Product Debugging:
1. After connecting with DC 5V (please notice the polarity), the digital tube will display -.000 or .000,this is normal.
2. Use multimeter to measure the voltage between chip 36-pin and 35-pin,and adjust VR1 potentiometer let it be 100mVKey Points Voltage Reference Value:
1.Chip 1-pin and 21-pin voltage 5V
2.Chip 36-pin and 21-pin voltage 100mV
3.Chip 26-pin and 21-pin voltage -5V
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