Lm2917

[iz3dmq]

Hello to everyone.
sorry if i'm opening another post about LM2917; sorry again,I'm Luca From Verona , north Italy , i asking if someone can halp me to convert my anemometer with magnet and reed contact , with an easy LM2917/14 pin.
i've found something here but only for AC waves and LM2917/8.
i have some LM2907/8 too,...
please if anyone can help me with a picture of schematic diagram.
bye and hello to everyone

 

[Norlin]

**broken link removed**
has a picture for something that might be useful, didn't look too closely, so you'll have to decide for yourself

 

[iz3dmq]

Hello and tks for your reply.
i'm trying to see it not too closed , but i have a 14 pin and i don't know like i can connect the others.
than , i see a magnetic pickup that probably gives an AC not from zero reference.
i have a reed contact , i could connect a resistor to the power of 5 Vcc and the other side to the ground , than pick up the contacts from the reed.
do you think that i'm doing a good job? or it s better use another resistor from the ground the the second terminal of my reed?

bye and tks
so long

 

[RODALCO]

Hi Luca,

From a different angle and perhaps easier to build is to get hold of an old VCR , photocopier or printer, light running steppermotor, and attach it to the anemometer propellor, and drive an electronic speedo from a car with it.
You get impulses directly proportional with the windspeed.

I have an old Holden speedo cluster which works of 12 Volts. An extra pin at the speedo requires a pulsetrain which you might be able to collect from the steppermotor, and directly read the windspeed in km/h. As extra bonus is that you get actual kilometres recorded as well on the odometer.
You may need to use a schmitt trigger to clean up your pulses and a 4017 to get the pulsecount correct.

This example is an idea I have already for quite a while but haven't had the time to implement it yet.
I know that the speedo works very precisely when the steppermotor is turned around by hand.

Regards and good luck with the project ,
Raymond