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Forum Index : Electronics : Converting a monitor into a cro.
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I have a old Macintosh Plus computer that I want to convert into a simple low frequency cro. For those that remember, the Mac plus was a 1 meg machine, no hd, just a floppy. Late 80's I think. It does go, but I dont have the boot disc and its not really usefull for anything these days anyway. Its a neat little case, has a 9 inch screen, heaps of room inside and on the front panel to mount dials and switches, etc. I disconnected the deflection yoke and it still runs, nice little dot on the screen. So I only need to feed a deflection saw tooth waveform into the horizontal coil, and connect an audio amp onto the vert coil. Has anyone played around with this sort of conversion before, and could offer some tips? Its all pretty straight foward stuff, but I dont want to reinvent the wheel, so any help would be appreciated. I only expect a frequency response up to 20kHz, just handy for testing audio circuits and wind generators Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Chris Senior Member  Joined: 12/09/2005 Location: AustraliaPosts: 146 |
lol what a co-incidence... I was just thinking of trying to do this with a old monitor i have lieing around. I got no idea on how to do it though. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Chris. I played around with the idea when I was a kid, but didn't really have the know how. Still dont. I had a old B&W tv. I was lucky and the beam was still on when I disconnected the yoke, most tv's need the horz yoke for the EHT circuit to work, but this one didn't. I connected an audio amp to the horz deflection coil and fed in a sinewave, that gave a very un-linear trace across the screen. Then I fed audio into another amp across the vert def coil, and wha-la, I had a rough un-calibrated cro! To do it right, I need to provide a triangle wave fed into the horz coil. Variable frequency to give me a range of 10Hz to 20kHz. Some sort of blanking to kill the retrace of the beam. And trigger circuit. The vert deflection is easy, just a good audio amp, only need a couple of watts to give full deflection. Its one of those projects that will take a year to finish. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
I googled it before, it doesnt seem that hard to set up.
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. The hardest bit to design are the horz timebase circuits, and trigger.
