Question about circuit

Here is the data sheet for the chip:

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.

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

i will do that and see if it works.

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