I have a 555 timer that creates what I believe to be a square wave. This 555 timer feeds into a 4 bit counter (only using 3 bits) and from there into two separate 8-1 multiplexers (74LS151).
One of those has bit 0 set to high and the other one has bit 4 set to high.
The two outputs I get create alternating pulses like so:
output a: 10000000
output b: 00001000
Then I use the inverse of output b:
output b: 11110111
Now here is where my trouble starts. For the J-K flip flop I use a 74LS76. I put J, K, and preset to high and clock to output a and clear to output b.
I want to create a perfect square wave with these pulses, such as that I can prevent one of the output b pulses from reaching the flip flop and in that double the period.
when output a goes high, the flip flop starts blinking almost sporadically. Even when I put clear on high, the flip flop is supposed to toggle which each pulse coming from output a but on my board it's toggling more often than this output a signal.
the weird thing is, if i send the clock signal with a parallel port instead of the previous circuitry, then the flip flop behaves as expected. The output toggles with each falling edge of the clock signal.
Could it be possible that the multiplexers sending the pulses are actually sending many pulses or a "rough" type of signal that look like pulses to the eye? I don't have a oscilloscope available right now, hence I'm only guessing.
I'm posting this because I might be missing something obvious, like a capacitor in the right place or another component.
To summarize, everything from the 555 -> counter -> multiplexers is keeping pace until the flip flop, that's acting up.
I can provide a schematic if needed. thanks for any help.
One of those has bit 0 set to high and the other one has bit 4 set to high.
The two outputs I get create alternating pulses like so:
output a: 10000000
output b: 00001000
Then I use the inverse of output b:
output b: 11110111
Now here is where my trouble starts. For the J-K flip flop I use a 74LS76. I put J, K, and preset to high and clock to output a and clear to output b.
I want to create a perfect square wave with these pulses, such as that I can prevent one of the output b pulses from reaching the flip flop and in that double the period.
when output a goes high, the flip flop starts blinking almost sporadically. Even when I put clear on high, the flip flop is supposed to toggle which each pulse coming from output a but on my board it's toggling more often than this output a signal.
the weird thing is, if i send the clock signal with a parallel port instead of the previous circuitry, then the flip flop behaves as expected. The output toggles with each falling edge of the clock signal.
Could it be possible that the multiplexers sending the pulses are actually sending many pulses or a "rough" type of signal that look like pulses to the eye? I don't have a oscilloscope available right now, hence I'm only guessing.
I'm posting this because I might be missing something obvious, like a capacitor in the right place or another component.
To summarize, everything from the 555 -> counter -> multiplexers is keeping pace until the flip flop, that's acting up.
I can provide a schematic if needed. thanks for any help.