Study the Analog to Digital capabilities of Atmel ATtiny26. This tiny but mighty IC is really a miracle. One special thing is the internal 10-inputs multiplexed ADC circuit which can covert analog voltages to bytes. This check circuit uses only 3 inputs. Of course you can may changes to use more inputs. I used the AVRISP in-circuit programmer to program the chip. You can see the connector for this purpose. The 10uH micro coil is for improving the voltage stability at the ADC section. It is not really needed for 8-bit resolution. Apply a stabilized voltage of 5Volts dc.