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Last Updated on:
Tuesday, November 29, 2011 08:14 PM
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Ten Turn Pot Forms
Frequency Readout |
This hobby circuit gates the output of a continuously operating 32KHz crystal
oscillator to the input of a C-MOS buffer when clock pulses are needed. The
technique gets around the problem of a slow starting crystal oscillator by
keeping the oscillator going and switching on a transistor power stage only as
needed. |
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The method keeps the standby power consumption to a
very low 1uA when used with a 3v supply. |
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Let’s say you are designing a signal generator for a
test fixture. To adjust the frequency you would like to use a ten turn pot with a
nice dial mechanism attached as a frequency display. However, a display range of 0
to 9.99 would be impractical since there is no such frequency as 0. But since many
pot dials have a display of "11" at the highest setting you could shift the
display for a range of 1 to 11 and get a nice linear function. The signal
generator circuit could then be setup in nice decade steps with a range selection
switch and get an overall accuracy of about 1/2%. |
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Click on Drawing Below to view PDF version of
Schematic |
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eMail David A.
Johnson, P.E. about this circuit |
