Mini Test Chart Generator
Recognise this? You have to adjust a television or monitor but do not have access to the required tools… This small test chart generator for less than a tenner is then just the bee’s knees.The circuit described here is actually just a standard video signal generator that can be used to synchronise a television or monitor, provided that the equipment being tested is fitted with a composite video signal (CVBS) input. All the timing and corresponding signal levels are generated by a PIC12C508 microcontroller. This circuit also has a second function. Many video recorders can record stereo sound. It is interesting to exploit this property to make a good quality recording from a radio broadcast, potentially using the recorder’s built-in timer. Unfortunately, modern video recorders switch to a background colour when they do not sense a proper video signal at their input. This prevents noise from being recorded, but at the same time the audio signal is also ignored!