ADC0808 – Simple Analoque to Digital Converter. The ADC0808 IC needs clock signal of normally 550 kHz, which can be simply produced from an astable multivibrator constructed applying 7404 inverter gates. In order to visualise the digital output, the row of eight LEDs (LED1 through LED8) have been utilized, wherein every single LED is connected to respective data output lines D0 through D7.