hi guys this is the complete schematic.
& one thing is that i am supplying this counter from a nokia mobile charger which is 5v & 800mA.

 

Hello,

It looks like the way you connected the 555 it is an oscillator that is switched by the optocoupler.
This will be instable, as the 555 will get not enough power.
What do you want the 555 to do?
Is it to make a single pulse when the interuptor is powering the 555?

Greetings,
Bertus

 

bertus & sgtwookie sorry i forgot to indicate gnd.
this is new one

 

A quick obervation:

The photo-interruptor does not have a part number but I would venture to say that the photo-emitter appears to be wired in the reverse direction.

hgmjr

 

Hello,

Yes, hgmjr, that is a sharp view.

For the 555 take a look at this page for the possibilities:
http://www.uoguelph.ca/~antoon/gadgets/555/555.html

Greetings,
Bertus

 

yes bertus 555 here is an oscillator.
i connected 555's pin#4 & 8 to photointerruptor's output.Motor has one opaque flap & anoter is transparent when motor rotates the opaque flap comes in photointerruptor's slot & display show one count.i just used 555 for giving only one pulse in result of one interreption by opaque flap as in the begining of this case i asked u that my counter gives unstable counting for one pulse then u advised me for using 555.

 

yes hgmjr i did mistake in drawing figure the 1k is on anode of photo emitter & cathode is ground.

 

Hello,

You can connect the pin 8 of the 555 to the powersupply.
Use pin 2 to trigger the 555 as in the picture below:

For better reaction of the interuptor reduce the 1K resistor for the led to 390 Ohms.

Greetings,
Bertus

 

in above figure where should i connect output of interruptor?

 

Hello,

Pin 2 comes from the transistor-output of the interuptor.
Pin 3 goes to the counter.
Pin 4 should go to +Vcc unless you want the counting to stop.

Greetings,
Bertus

 

in that fig can i used same 100k Potentiometer for Ra & 22uf for C as in schematic i post u?

 

Hello,

The 22 μF is pretty large.
This will limit the number of RPM's dramaticaly.
Use 0.1 μF as first try.

Greetings,
Bertus

 

bertus plz tell me the suitable resisitance for Ra & Rb in your given schematic.