• on Audio/Video/Photography
  • Published in issue 7/2003 on page 0
About the article

Mini Test Chart Generator

A video test chart for less than a tenner

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!
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Resistors:
R1-R4= 1kOhm2
R5= 120Ohm
R6= 75Ohm
Capacitors:
C1= 100nF
Semiconductors:
T1= 2N2222
IC1= PIC12C508C (Microchip)
Miscellaneous:
X1= 4MHz quartz crystal
Disk, PIC program, order code 020403-11 or Free Download
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