Picture of Mullard Pupil's Oscilloscope
This instructable describes the construction of a extremely simple 12v oscillosope.

The diagram below is a schematic of the Mullard pupil's oscilloscope.  This is a single valve (+CRT) oscilloscope that is about as simple as an oscilloscope can get.  The Mullard scope is described in the Radio Basics column of Practical Wireless March 2005.
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Step 1: Transformer Winding

Picture of Transformer Winding
The transformer was home wound on a ferrite core that I had handy and an aluminium clamp fabricated to enable it to be fixed to the chassis.

Transformer Winding Details:
L1,L4 12 turns 26 swg
L2,L3 3 turns 26 swg
L5 450 turns 36 swg

Step 2: Construction

Below are pictures of the oscilloscope during construction and completed.  The scope shown above did not include the X attenuator potentiometer shown in the circuit diagram.  I also added a 68pF capacitor between the Y amplifier anode and the supressor grid of the timebase pentode to provide a sync. signal.
robot79710 months ago
how much volts on the high voltage?
Parcgwyn (author)  robot7977 months ago
Sorry for the late reply, I think it is about 275 to 300V.
I like this.

Where did you get the cathode tube?

All of mine are over a foot long and six inches wide.

Have you seen my Instructable, Building a Digital Oscilloscope from a DIY Kit?
Parcgwyn (author)  Josehf Murchison1 year ago
Hi Josehf,
I purchased the cathode ray tube from ebay for about £15 in the UK an alternative to dh3-91 is the 1cp1. Thanks for the link to your page I have seen this kits advertised and may buy one in the future.
Cool I was looking at another Instructable they got there tube from an old video camera.