problem 0f 7490 in counting

Thread Starter

Afeesh a n

Joined Jun 12, 2009
i have configured a 7490 as a decade counter. but as the pulse come the counter is counting with 2 ie. 1 3 5 ......what may be the problem the pulses are coming from a monostable multivibrator with time period of plz do suggest some idea to eliminate this.

thank u


Joined Jul 17, 2007
Are you using bypass capacitors on both your astable multivibrator's Vcc/GND supply AND the 7490 supply pins? If not, there's a very likely cause.

Are your interconnecting traces/wires/jumpers long? Try to keep them as short as possible; long wires have a good deal of inductance, and will cause circuits to oscillate unexpectedly.