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Convert pulse frequency to DC volt??

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settra

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hey forum. i have a hall effect sensor, measuring the RPM of a wheel, with one magnet attached to the wheel. every time the wheel magnet passes from the sensor, it goes low.... so, one pulse per revolution...

i want to convert that signal, to analogue... 0 rpm = 0volt, more rpm = more volt (max 5v)... any ideas how can this work??
i have found LM2907 , which is an Frequency to volt converter, but it is supposed to work with VR sensors (who outpout -V as well). do you think it would work with a hall effect sensor switched to ground??

what else could work?? thanks!
 
hi settra,
The LM2907 should work OK, do you have a datasheet to post for your Hall effect sensor.?
E
 
I Don't really have any info on the hall sensor... :/ but its the plain simple style. i had asked "give me one hall effect sensor" , and took what the shop gave me , so... is it for something important?
as i remember, the Vcc and signal, are tight together with a 10k pull up resistor!
 
If the Hall effect works with a 5V supply and its output swings from approx 0V to ~5V, it should not be a problem driving the Lm2907
 
its something like that for sure. BUT , the otpout is 5v, and swings to 0v ... (so its 5v most of the time )
 
any other way i could do that?? becouse it might not be easy for me to find a LM2907 where i leave... :/
 
any other way i could do that?? becouse it might not be easy for me to find a LM2907 where i leave... :/
Whats is the highest RPM you need to measure.?
 
You can use a 555 as a frequency meter, do a google.
 
enothet thing, is that i want outpout 0-5 v... i think that LM needs 12v min....
highest rpm? i dont think more than 1000rpm, considering that the typical car wheel is 16" diameter...
 
after all, i managed to find, lm2907 with 16pins, and Lm2917 with8 pins.... do you think that the wire up should be the same???
 
after all, i managed to find, lm2907 with 16pins, and Lm2917 with8 pins.... do you think that the wire up should be the same???
The datasheet for the LM2917 shows similar circuit examples as the LM2907.
So either type should be OK.

Have you considered the 555 option.?
 
hi,
This is a rough idea of the Vout you will get, the actual Vout will depend upon your components.
E
 

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i cant seem to be able to get it to work.... i could see the lm555 as well, but i dont seem to be able to find a a good circuit describing how... :/
 
i cant seem to be able to get it to work.... i could see the lm555 as well, but i dont seem to be able to find a a good circuit describing how... :/
Please post your circuit and if possible a photo on how its connected, it should work.
 
its like the one you posted, but :

i give direct dc to pin one, with a pushbutton (although i tried with a 22pf cap)
c1 = 2.2uF
R1= 100k
and i also have no C2, but i think that this is for ripple only....
maybe i have arledy burned it ? :p
where did you made the simulation ? :)
 
Another, this one has some amplification on the front end:

**broken link removed**
 
hai settra....
i have problem like you, i want to convert sensor hall effect with pulse widht to voltage.
i have IC LM2917 (14 PIN), but not succes to convert voltage 0-5 VOLT, i want to try use IC 555.
if you succesfully with your circuits, please post the circuits.

thanks
 
Howdy, I built speed & tach measurements for a motorcycle instrument complex by timing the span between pulses.
It's then a straightforward calculation to MPH or RPM. The other numbers are time constants or stuff like tire diameter.
This is predicated on using a microcontroller, so may be somewhat advanced. I wasn't born knowing it either... G.H. <<<)))
 
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