Ah, that explains it. I wanted a +/-5V sawtooth output. Also, I
DC-coupled the sawtooth to the square-wave comparator, so as to have no
lower limit on frequency of the square wave. This required the
symmetrical sawtooth as well.
-Richard Brewster
sasami@... wrote:
DC-coupled the sawtooth to the square-wave comparator, so as to have no
lower limit on frequency of the square wave. This required the
symmetrical sawtooth as well.
-Richard Brewster
sasami@... wrote:
>>I do have a question for Ken. The sawtooth buffer amp shows a 330K
>>feedback resistor and a 240K bias on the schematic. I inserted pots and
>>adjusted to get a +/-5V sawtooth. The values turned out to be exactly
>>200K / 600K, just like the ASM-1. This is also just what you would
>>expect to convert the 0-5V signal out of the CA3140. Double the voltage
>>(200K/100K), then offset the 0 to -10V result back to +/-5. I think
>>maybe the 330K/240K values are for a +/-12V power supply.
>>
>>
>
>More thoughts on this - the ASM-1 sawtooth is centered around 0V, while the
>output of mine SITS on 0V, so it is 0V-10V. The +/- 5V wave form is then
>available from the AC coupled output. There may be slight offset
>differences when running off 15V instead of 12V, but the above is the
>primary reason for the somewhat different values.
>
>Ken
>
>_______________________________________________________________________
>Ken Stone sasami@... or ken@...
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