THE GREAT MULLARD MAGIC BLOG — MONOSCOPE

Now here’s something you don’t see every day – it’s a Monoscope. These were invented in the immediate post war period in the GEC laboratories at Wembley following on from the need for broadcasters to derive a signal with which to test their equipment. Within the cathode ray tube (CRT) of the monoscope, a solid silver plate, photo etched, curiously using photo sensitive fish glue (yes, really!) and carbon coated depicted the information that had to be produced – in the case of this device, the redoubtable BBC Test Card C.  A signal was generated as a focused beam of...