Using the X-Y display mode of an oscilloscope and digital-to-analogue circuitry created with an R-2R ladder, Kapil Gupta has made a simple and effective analogue clock display for the oscilloscope. He has also added a temperature display which uses a thermistor for measurement. The circuitry fits neatly on a protoshield, as you can see in the following detailed demonstration video:
When working with time and Arduino (or any other system with the I2C bus), consider using our super-accurate real-time clock module. Based on the DS3232, it has a temperature-controlled crystal oscillator for accurate time keeping, battery backup and 236 bytes of non-volatile memory for user data. For more information, see our modules page.