ds18s20
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Yes, a resistive divider will work just as in the DC world at low frequencies.bbiandov said:What I am talking about is good old 50Hz 500mA source - I need to know if resistor network will divide it just as it would in the DC world and also when one runs the numbers - is the norm to use rms for calculations and all intensive purposes?
Google for "variac" or "variable autotransformer."bbiandov said:I also need to know if there is such thing as adjustable AC voltage regulator - I just need to have few different AC voltages for this weird display and I cant figure out how to produce them - all I have is DC gear?
Google for "variac" or "variable autotransformer."
lambtron said:What are the display's requirements? That is, what AC voltages does it need, and at what currents and frequency? Are they all fixed voltages?
No, that won't work because the opamps are running open loop.ds18s20 said:... you mean hook up the op-amps like this:
lambtron said:ds18s20 said:phase with each other, to generate a differential 3.5VAC after passing through low-pass filters. The filters are followed by power opamps, which in turn directly drive the filament.
The low pass filters probably don't need to be "perfect" as the filament has some inductance that will help to smooth out digital edge effects that are not blocked by the filters.
Note that the AC waveforms have a +1.75V bias because their negative peaks bottom out at 0V. Because of this, you may need to increase the anode voltage by an equal amout, from 20V to 21.75V to keep the display happy.
Hi,
Thanks, that schematic makes a good point. Just one question - what's the math behind it? How did we get a 3.5V amplitude out of a 5V square wave signal which comes out of the micro just by passing via the filter? Then how did we get 50 msec period out of a 1kHz square wave, again just by passing via the filter. Lastly how do you figure 1.75V bias?
Ahh and the output AC - why isn't that 7V p-p, if we have each composite amplitude go to +3.5V? The output should see 7V p-p wouldn't it?
Thanks
~B
ds18s20 said:How did we get a 3.5V amplitude out of a 5V square wave signal which comes out of the micro just by passing via the filter?
ds18s20 said:Then how did we get 50 msec period out of a 1kHz square wave, again just by passing via the filter.
ds18s20 said:Lastly how do you figure 1.75V bias?
ds18s20 said:Ahh and the output AC - why isn't that 7V p-p, if we have each composite amplitude go to +3.5V? The output should see 7V p-p wouldn't it?
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