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Circuit Principle:
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, which generate -5V voltage is input by chip 26th pin.
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 100mV.
Key Points Voltage Reference Value:
1.Chip 1-pin and 21-pin: 5V.
2.Chip 36-pin and 21-pin: 100mV,
3.Chip 26-pin and 21-pin: -5V.
Specification:
Material: PCB + Metal + Plastic
Type: Digital Ammeter Kit
Panel Size:79 x 44mm / 3.11 x 1.73in
Mount Size:71 x 39mm / 2.8 x 1.53in
Quantity: 1 Pc
Electricity Parameters:
Working Voltage: DC 5V
Working Current: 35 mA
Accuracy: ±1mA
Measuring Range: 0 - 2A
Over Range Indication: Primacy Display 1/-1
Display Color: Red
Quantity: 1Set
Package includes:
1Set x Digital Ammeter Kit