1950s Oscilloscope into a 405-line TV
The Industrial Electronics Model 1200B is a compact London-made oscilloscope from the early 1950s, with a 7 cm Mullard DG7-5 tube and DC-coupled push-pull EF36 amplifiers on both axes. That is most of a 405-line picture monitor already: the scope keeps its tube, EHT and deflection amplifiers.
An add-on box makes the line and field ramps from the sync pulses and drives the grid, using the VCR139A monitor's sync separator, timebases, video amplifier and spot-kill. The only change inside the scope is a clamp diode on the grid, which unsolders to turn it back into a scope. Addendum A swaps the discrete sync separator for an LM1881, now tested on 405 and 625 lines.
At a glance
| Scope | Industrial Electronics 1200B, 1951–54 |
|---|---|
| CRT | Mullard DG7-5, 7 cm green, electrostatic |
| Picture | About 48 × 36 mm, 405 lines (625 and 525 also) |
| Status | Scope working; sync separator tested; timebases being built |
Block diagram
Click a drawing to open it full size.
Documentation
The full design report, schematics and parts list will be published here once the project has been built, tested and filmed.