Description: 89C2051 digital clock kit, control chip AT89C2051, digital control using three two common male red LED digital tube display high definition brightness, because the scan is displayed, so that each digital control abcdefg each foot with a bus in parallel, change the resistance value R4-R10 can change the display brightness. S1 button is used to calibrate the time, press and hold for more than two seconds to enter the calibration time status and exit quickly tap for adjusting the time value. The circuit has added a 3V battery backup, power outage AT89C2051 using spare batteries, the clock does not stop, but digital is not displayed after the call backup battery out of action, AT89C2051 uses an external power supply, the digital tube display properly. So you can add a power switch, turn off the power when they go out, come back out again, the normal display, to achieve the purpose of saving electricity. Time accurate. Specifications: Model:AT89C2051 Working voltage: DC 6-12V Recommend voltage: DC 9V Working current: 35mA Standby current: 1.2mA Specifications: 89C2051 digital clock kit, control chip AT89C2051 The circuit has added a 3V battery backup Time accurate Durable and practical 100% brand new and high quality Package Included: 1 x Set DIY Kit Module LED Electronic Clock Parts Components Notes: Due to the difference between different monitors, the pictures may not reflect the actual color of the item. Compare the detail sizes with yours, please allow 1-3cm error, due to manual measurement. Please leaving a message before you give the bad feedback,if the products have some problems. Thanks for your understandings.