USB 5V Four Digital DIY Clock Kit Two Alarm Function

by April 30, 20150 comments


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USB 5V Four Digital DIY Clock Kit Two Alarm Function


Supply voltage: USB (5V)
PCB size: 108 x 36mm
Display color: Red, blue optional

Based on AT89C2051 microcontroller:

1. Two Alarm
2. 8:00 – 20:00 hour chime
3. Accurate working time
4. Precise setting time
5. Power Off Memory
6. Large screen display (1 inch LED)


The entire circuit contain the smallest system, keybutton input circuit, display circuit, buzzer circuit, power circuit and Backup battery power supply circuit.

1. The smallest system: including U1 (AT89C2051), R5 and RET manual reset circuit, C2, C3, Y1 constitute a clock circuit.
2. The key input circuit: including S1 and S2, short press the button buzzer once, long press    the  button buzzer twice.
3. Display circuit: contain with four common anode and Q1-Q4 transistor drive circuit.
4. Buzzer circuit: contain with Q5, R6 and LS1 components.
5. J3 is 5V power input, C1 filtering.
6. The backup battery power supply circuit: contain with BT1, D1 and D2, when external 5V power supply, D1 is turned on by a 5V power supply, then D2 is turned off, the backup battery BT1 no current consumption. When the external 5V power outage, D2 immediately turned on, BT1 power supply.

User manual: Click to open

Package included:

1 x DIY clock kit