555 / 74LS107 Problems

Thread Starter

benjam47

Joined Oct 4, 2013
2
Hi everyone,

I am trying to use a 555 to drive a 74LS107 JK flip flop.

I am using a 36k and 18k resistor, and a .1uf capicator. The 555 is producing the expected clock at a 75% duty cycle.

However, the Q output of the 74LS107 is following the output of the clock, instead of only flipping on the negative edge. I have the J, K, and CLR lines all tied to positive.

Pictures of the project and the scope are attached.

I am a newbie at this, just trying out some projects for personal enjoyment, so I suspect I've done something dumb. But I have tried replacing chips, looking for wiring faults, and am now out of ideas.

Thanks for any help!
 

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MrChips

Joined Oct 2, 2009
19,280
Glad we can help.
Next time get help fast from AAC.

100μF across the supply might do the trick, but do put a 0.1μF capacitor across pins 1 and 8 of the 555 circuit!
 
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