About this project
My project is an oscilloscope clock. The clock can be built to display the time on a cathode ray tube. I have worked on perfecting this design for years, and now I have a nearly completed project and I am ready to produce a first run. The board is an upgrade of a previous version with several very important improvements. These include a better quality high voltage supply which produces "cleaner" and more stable high voltage, a more efficient blanking circuit that eliminates almost all retrace lines, a dual primary transformer to allow line supply from 120VAC (U.S) or 240VAC (some other countries) as well as a battery backup option which uses a standard nine volt battery, and firmware upgrades to support these new features. The prototypes are displayed using a 6Lo1i (Soviet) crt and a 2AP1 crt, but the design can be used with many other small, low voltage crts like DG7-32, DG7-6, 2BP1, LB-8, 50HB1, 7SJ33J, 3SP1, B7S2, LO-247, 3GP1 and many others.
I plan on ordering a 35+ run of the pc boards, using the design files of the prototype run. I already have quantities of the components stocked, and plan to stock enough to complete all 35. I have accumulated a collection of crts over the years with this project in mind, and have more than enough in stock to fulfill the rewards for this project. I craft the bases for the crt and boards to mount on from 1/4" plexiglass stock, and thermoform the dust covers from 1/8" plexiglass. The circuit board measures about 4" x 4-1/2" (about 10cm x 11cm).
The scope clock started when I dreamed of building a clock using an oscilloscope crt, something that had become obsolete due to the advent of much thinner, wider displays like lcd, plasma and now led. I designed the circuitry for the kit board to be as compact as possible, while still using components big enough to be easy to work with and handle the wattage of the circuitry. After designing the pc boards, I wrote and debugged my firmware for the PIC microcontroller that makes the whole design work.
The concept is built around a digital circuit controlled by a PIC microcontroller running my original firmware. The digital circuitry controls a compact high voltage circuit which drives the crt. The crt's focus, brightness, and centering are adjustable, as well as the vertical and horizontal gain (size) of the display. The firmware allows the user to program the clock to turn the display on and off at preset user selectable times, while the low voltage circuit keeps time and settings. Optional battery backup from a standard nine-volt battery will keep the low voltage circuit powered up for days, preventing loss of settings and keeping time. The clock's feature of turning the display on/off at preset times is crucial to extending the life of the crt, this is a totally unique feature to my design that makes these clocks practical to run 24/7 while preserving the tube from burn-in
The boards will take about two weeks for production, and the 10 kits will be sent out within two weeks thereafter. The assembled clocks will ship about two weeks later, so the whole process of fulfilling rewards should take about six - eight weeks, following the project funding. My goal is to have the rewards fulfilled by mid - July.
The assembly instructions:
A great online store to buy crts (tubes):
Another great place to buy crts:
I also recommend this site for crts:
Risks and challenges
One of the challenges of building a clock this way is to design the circuitry so that it doesn't interfere with the display itself, since crts of this type use electrostatic deflection (a method of deflecting or moving the crt beam by using changes in voltages). The idea here is to create something not just functional but also visually appealing. This is as much a form of artwork as it is a technological curiosity. Another challenging aspect is to provide this in a form usable with many different types of crts, making it possible for builders to choose their own crt, possibly one already owned that is not used for any other purpose and would be left in obsolescence otherwise.Learn about accountability on Kickstarter
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