S
Steve Taylor
- Jan 1, 1970
- 0
We have an instrumentation application where we need to have a very low
power RF oscillator (30-50 MHz) sitting spinning on a small shaft. The
frequency of the oscillator is selected by a pair of capacitors which
are switched externally by a magnetically triggered reed switch. Our
exisitng brush-based system is a.) expensive b.) fiddly. c.)
unreliable. The existing system takes the RF back through the sliprings
to an amplifier for conditioning - we are only interested in the
frequency of the return, not its amplitude. The transmission distance is
about 12mm, 1/2".
We wondered whether we could use a solar cell to power the circuit, but
the typical output voltage is only around 0.7 volts, and there is not a
whole heck of a lot of space to get more in - the board diameter is no
more than 38mm (1.5 ")
Would LEDs of the same type as the emitters make efficient photo-cells ?
Ideally we would like to couple enough energy to modulate an LED
(different colour) at the RF frequency, to pick it up on a filtered
photodiode.
Any suggestions or comments would be gratefully received.
Thanks
Steve
power RF oscillator (30-50 MHz) sitting spinning on a small shaft. The
frequency of the oscillator is selected by a pair of capacitors which
are switched externally by a magnetically triggered reed switch. Our
exisitng brush-based system is a.) expensive b.) fiddly. c.)
unreliable. The existing system takes the RF back through the sliprings
to an amplifier for conditioning - we are only interested in the
frequency of the return, not its amplitude. The transmission distance is
about 12mm, 1/2".
We wondered whether we could use a solar cell to power the circuit, but
the typical output voltage is only around 0.7 volts, and there is not a
whole heck of a lot of space to get more in - the board diameter is no
more than 38mm (1.5 ")
Would LEDs of the same type as the emitters make efficient photo-cells ?
Ideally we would like to couple enough energy to modulate an LED
(different colour) at the RF frequency, to pick it up on a filtered
photodiode.
Any suggestions or comments would be gratefully received.
Thanks
Steve