tachometer using 555IC(10/1998)

[fever16]

i want to build LED based tachometer for my motorcycle.my friend gave me the schematic of tachometer published in ELEKTOR in 10/1998 http://fly.srk.fer.hr/~wgottwe/e98a034.pdf .it uses LM3914 as LED driver and 555timer for frequency to voltage conversion.
i bought every component and assembled on bread board.but its not working.
1.i used another 555IC insted of TLC555 is it ok?
2.for induction pickup i did exactly what mentioned in the article.as my vehicle is CDI i cant get signal from ignition coil.
3.when i measued the output as shown in the below pic.it was stable 5v without any effect to the RPM of vehicle.
http://img97.imageshack.us/my.php?image=0mh0.gif

i desperately need help to finish this project.
pls help me
thanks

[mark63]

Hello,

Tachometer
October 1998, 980077
In the parts list and the circuit
diagram, the value of R1
should be corrected to read
2.2 kO.

Mark

[fever16]

thanks for the reply.
i'll replace it.
but whats wrong with the 555 IC circuit.when i measue voltage between the JP1 and ground it is 5volts.where as according to the ckt it shld vary when i increase the RPM of motorcycle.
can u help mw with this 555 ckt problem.
thanks

[fever16]

iam using NE555 insted of TLC555.(can i use it or do i need only cmos version of 555).iam not sure abt it.
so i think this is creating the problem.

[Guest]

you definitely need the TLC555 or 7555. Apply pulses from a generator to C3 and work on the TLC555 circuit until it performs the frequency to voltage conversion function it was designed for. A few volts peak to peak are required to trigger the timer.

regards,
EE Labs

[fever16]

atlast its working.
i used 7555(as i was unable to find TLC555)and thick copper wire.when i change the number of turns of copper wire the range of LED's changing.(not by adjusting the P1 trimmer)
and in article they did't mentioned abt the PCB size.at what size i shld take printout so that i can use it for eatching.

[Guest]

please help me to build tachometer for my motorcyle