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FlyMario wrote:I have to look at this deeply sometime. I am fascinated that you are using Decade counters. I am always puzzled by doing that instead of using Binary Counters. I thought maybe you are making a DAC to control the horizontal and vertical position. But seems that binary would be more logical. So I must be way off
FlyMario wrote:hehe I bought a "Windsor Deluxe Portable T.V. AM/FM radio model VR-99" off of Ebay $16.00 to my door. I figured it might be fine as a first attempt at a tubed NBTV with all the stuff to drive the tube. I do want to make my round russian tubed one look so very nice so best to work out all the problems on something I don't care that much about.
FlyMario wrote:So, I am thinking about this when I should be working.
Let's say I have a tube and I need to generate 32 lines.
I have tons of ttl logic chips.
So say I have 4 bit counters which should be able to give me my 32 lines.
I hook resistors to the outputs from the pins to make 2 DACs.
One for the + direction of the electron beam and one for the - direction of the electron beam. I suspect I would need to go into an OPAMP to increase the output voltage. But how then do I get negative voltage? Do I make a voltage divider in the negative range and have the dacs fight against that voltage?
I take it that you can't get - voltage from a dc circuit. Do I need an ac transformer, like two half rectifiers and two huge capacitors to even get both sides. Seems I would need +12v gnd -12v right? the 12v part doesn't matter.
I went down this road when Klass and Steve mentioned doing all this in a DAC way ,i didn't have 1 % resistors so my first result was a bit primitive and all the wiring a DAC chip was the way to go here ,but if you can do it go for it that side i rather cut out all the resistors .
smeezekitty wrote:
If you have a trimmer resistor for each output bit, I am sure an R2R ladder DAC could actually yield quite a good result with a little tuning
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