Can a LM2907 be used to show higher/lower than center frequency ?

Thread Starter

Externet

Joined Nov 29, 2005
1,403
Hi.
The intention is to use a LM2907 that will turn a LED on when frequency is 60Hz +/- 5Hz and two more leds for frequency being lower and higher.
Does the LM2907 has any pin useable to tell if input is under or over the center frequency ?

It is for a adjusting the engine governors in portable generators, to be built in a wall wart case.
 

SgtWookie

Joined Jul 17, 2007
22,201
The LM2907 simply takes an input frequency and outputs a voltage that is relative in amplitude to the input frequency, depending upon component selection. I suppose you could add a window comparator to trip at the desired voltages/frequencies.

Your application simply screams for a microcontroller, used as a frequency counter. You could drive 7-segment LEDs to show what the actual frequency is. Or, you could use something like a bargraph LED to show more of a range.

[edit]
See this link for a PIC16F628-driven 5-digit frequency counter:
http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html
 
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