I posted a thread about a lower power anemometer here:
https://www.electro-tech-online.com/threads/low-power-analog-wind-sensor-anemometer.22595/?highlight=anemometer
I followed the steps outlined in the Easter Egg Anemometer site, however I am having some trouble with the LM2917 Frequency to Voltage chip from National Semiconductor.
My circuit looks exactly like this:
**broken link removed**
All of my components are the same. However, I don't think that I am wiring up my AC frequency-in correctly. For my AC frequency, I want to use a reed switch / magnet to generate voltage pulses. Is this how I am supposed to wire up the reed switch (ASCII art time):
----- 2.5V
|
|
/
|
|---- LM2917 PIN1
|
----- GND
The "/" is my reed switch. When a magnet passes over the switch, the switch closes and current should flow through. When I hook it up like so, I get no reading from the LM2917. When I attach an external signal generator to PIN1, the LM2917 reads accurately. I believe that I am just doing the AC frequency-in incorrectly. I think that I should be putting a resistor between GND and PIN1, but I am not sure.
Any suggestions or tips will be greatly appreciated!
https://www.electro-tech-online.com/threads/low-power-analog-wind-sensor-anemometer.22595/?highlight=anemometer
I followed the steps outlined in the Easter Egg Anemometer site, however I am having some trouble with the LM2917 Frequency to Voltage chip from National Semiconductor.
My circuit looks exactly like this:
**broken link removed**
All of my components are the same. However, I don't think that I am wiring up my AC frequency-in correctly. For my AC frequency, I want to use a reed switch / magnet to generate voltage pulses. Is this how I am supposed to wire up the reed switch (ASCII art time):
----- 2.5V
|
|
/
|
|---- LM2917 PIN1
|
----- GND
The "/" is my reed switch. When a magnet passes over the switch, the switch closes and current should flow through. When I hook it up like so, I get no reading from the LM2917. When I attach an external signal generator to PIN1, the LM2917 reads accurately. I believe that I am just doing the AC frequency-in incorrectly. I think that I should be putting a resistor between GND and PIN1, but I am not sure.
Any suggestions or tips will be greatly appreciated!