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Question about circuit

J

John Popelish

Jan 1, 1970
0
ahonda55 said:
Hi all , this is a tachometer circuit in this page..

Please see it ..


http://www.niksula.hut.fi/~mdobruck/siililand/mini/diy/alien/tacho/tacho.html

as the author wrote "Therefore if the output is linear then we have 1V
for every 2000rpm. "

i want to make it 2v or more for every 2000 RPM .

How can i do this ??

Thanks a lot :)
Here is the data sheet for the chip:
http://www.emesystems.com/pdfs/parts/LM2907.pdf

Read page 7.

There are a couple ways to increase the output by a factor of 2. You
could double the size of the timing capacitor, C1, or you could double
the value of the load resistor, R1. Or you could change both values
such that their product is twice the listed values for C1 and R1.
 
A

ahonda55

Jan 1, 1970
0
Thank you very muc
I did that already , but i need to increase the (sensetivity) of th
tachomete
for example, at 2000 RPM 1v , at 4000 RPM it should be 2v , i want t
make it 3v or more

i will try to reduce the (ref. high) in the LED driver IC LM3914,
think it may work

if it worked i wil post the result here

Thanx a lo
 
E

ehsjr

Jan 1, 1970
0
ahonda55 said:
Thank you very much
I did that already , but i need to increase the (sensetivity) of the
tachometer
for example, at 2000 RPM 1v , at 4000 RPM it should be 2v , i want to
make it 3v or more.

i will try to reduce the (ref. high) in the LED driver IC LM3914, i
think it may work .

if it worked i wil post the result here.

Thanx a lot


From the datasheet John mentioned:
Vout = Vcc * Fin * R1 * C1 * K
(K generally equals 1)
Try changing C1 from 47 nF to 100 nF and see if that gives you
what you want.

Ed
 
A

ahonda55

Jan 1, 1970
0
i will do that and see if it works

i dunno how to thank you Ed :) and all of you :
 
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