My mistake not telling that is not exactly the schematic for my application... this is one i find from the net and want to see if this is the right connection for 20 leds in bar mode...
in my project as it is a car... will be 12v supply to a lm7808 and then to the lm3914
A 1N4148 (or 1N914) are signal diodes that work well at the many frequencies and low currents of a tachometer and should be used.
A 1N4001 is a very slow rectifier designed to work at only 50Hz and 60Hz but it might work in a low speed tachometer circuit.