My project is a homemade analog oscilloscope clock, similar to my previous designs but differing in the manner the display is created. The segments which make up the characters are generated as a continuous line, arc or circle by using an analog switch and digital potentiometers and rheostats controlled by a microcontroller to manipulate an analog signal (sine wave) from an oscillator. This is quite different from my previous method of using vectors (dots) to draw the display point to point. The board has pots to adjust vertical & horizontal height / width, focus, astigmatism, brightness, and vertical and horizontal centering, as well as oscillator shape, oscillator gain and phase shift.
It starts with the same basic design as my previous models, using the same type supplies for high voltage & low voltage, the same wave shaper to pick up and convert 60/50HZ and the same blanking and deflection circuitry, with some slight changes. The new method of actually drawing the display begins with an oscillator configured to generate a sine wave which is switched by an analog switch to the deflectors, and positioned & sized by the digital pots. The microcontroller programmed with my firmware handles all this amazingly well !
The kit comes with everything you need to build it yourself, except the crt and an enclosure. It should work well with most small relatively low voltage crts, as in my previous kit version. The kit will be a really challenging build, which will make it the more rewarding to the builder who is able to complete it and adjust the controls to optimize the display ! As always, I will be available for Q & A and ready to supply any docs I have for different crt types. It is also possible to exchange the microcontroller for a new one with upgraded firmware, since the IC's are all in sockets.
The deluxe version will be built using the pledger's choice of either the DG7/6 or the very nice DG7/12-C which has very high quality resolution & focus as well as gold-plated electrodes. I will use gold pin sockets and the $345 or higher pledge will also come with a future firmware upgrade (when available) and for any pledge $500 or more I will build the deluxe version with any type of crt the pledger chooses as long as it is possible.
I would like to produce a run of a hundred boards or more with this design. I currently have a prototype run of four boards and will need to make another prototype run to correct some minor errors first.
Some points of interest: All the components on my clocks / kits are replaceable/repairable because they are all standard size, not SMT The IC's or "chips" are socketed so they can also be replaced easily, even by the layman In many cases, I will repair the clock free for any reason if you ship it back to me - i.e., if a component fails or is damaged (except the tube(s)) All of my clocks use standard electric service (do not need a separate power supply) and most can be set for 120VAC (U.S.) or 240VAC (others) Instruction set for scope clock ______________________________ When plugged in, the blue led should light immediately, and there should be a small "click" of the relay engaging. After several minutes, the filament should warm sufficiently and the screen should display "1", (number one). This means 60HZ was detected, and set accordingly. If a zero appears instead, then 50HZ was erroneously detected (unless your country uses 50HZ mains of course). Unplug, wait until the blue led goes off, and then plug back in. The time set buttons are a pair situated close together, one is fast set, and the other slow set. To set time without programming any preset on/off times, just press the slow set button (on the left) once and the clock display should appear, then use the two buttons on the front to set time. To manually turn the display on/off, press the toggle button (separate from the two set buttons). To program the preset on/off times: First press slow set to enter normal timekeeping mode, then press the fast set & slow set buttons at same time and the screen should display 12:00:00. Press the fast set button to increment the hours. Each time that button is pressed, the hours should increment once. When the desired hour is shown for ON time (AM only), Press the toggle button to advance to the next screen and the display should change again to 12:00:00. Follow the same procedure, and after the OFF time is selected, either press slow set to enter normal timekeeping (fast set / slow set) mode or, to set the second set of preset on / off times, press toggle and follow the same procedure, except this time you will be selecting first a PM on time and then an AM off time. Please refer to the youtube link for illustration: Note: The clock will display 12:00 AM to start, so if the present time is after noon, you will need to advance the time past 12:00 in order to reach the PM hours, else the preset on/off times may be reversed. I.E.: if the present time is 8:00 PM, you need to advance PAST 8:00 once, and then stop at 8:00.
A place to buy some crts: http://www.sphere.bc.ca/test/crts2.html
Risks and challenges
Designing the circuitry to drive the analog portion of this clock was challenging ! I wanted everything to be as simple as possible and to be driven by a single 5VDC supply. I also wanted to fit the entire circuit on one board, and that board to be the same size as my previous mini scope clock board, OSC4.3. The risk of doing it this way would be not to sacrifice the quality and still keep the cost down. Overall, I am very happy with the design. I plan to continue to work on the firmware to create an analog clock face in the future to alternate with the digital display as in my previous design.Learn about accountability on Kickstarter
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