Hey thanks for your reply Pencil.

I chatted with Austin and we got the problem fixed. I needed to ground some of the pins and I needed to switch from 7.5 volts to ground over and over instead of using a push button switch.

I got that working, but now I am having trouble getting his Op-Amp circuit to work. I am waiting to chat with him again. I can't seem to hook up the op-amp to work properly....

 

I am having trouble getting his Op-Amp circuit to work. I can't seem to hook up the op-amp to work properly....

If you post the complete schematic with a part number for the opamp then we can help you.

 

I now have the Op-amp working and I need to use it as the CLCK input on the D Flip-Flop. The problem is it's a "pull-up" op amp and it is not giving me a full cycle on the CLCK. As Austin told me, you need to have a full cycle for the clock to register.

Austin told me this was possible using the op-amps output and a transistor. We never finished the conversation though. Does anyone know what he was getting at?

To summarize...I need to use the Output of an Op-Amp to trigger the CLCK of a D Flip-Flop.

 

We DO NOT know what is going on since you refuse to post the complete schematic with a part number for the opamp.

 

Why did you post ANOTHER thread about the LM339 COMPARATOR (which is not an opamp)?
http://forum.allaboutcircuits.com/showthread.php?t=76985

 

Sorry, here is the schematic I drew up.

EDIT: Full picture doesnt want to show up. Click here to view it.

As of right now, the left and right are independant circuits and do not interact with each other.

On the left: This is my comparator with the LED. When the light is shone on the photo-resistor, the LED lights up.

On the right: This is the D Flip-Flop. I need to connect the CLK to the comparator in such a way that shining the light on the photoresistor will make the D-Flip Flop change states.

 

Why did you post ANOTHER thread about the LM339 COMPARATOR (which is not an opamp)?
http://forum.allaboutcircuits.com/showthread.php?t=76985

They are mostly the same. The difference is usually just slew rate and output type, at least that I'm aware of. So, in essence, don't bag on a guy for "technically" using the wrong name.

 

Your LEDs do not have current-limiting resistors so the LEDs and/or ICs might blow up if they have a high output current. Also the LEDs are restricting the voltage swing so the CLOCK voltages are not valid.

Why do you use one quarter of a big LM339 quad comparator IC instead of one half of a little LM393 dual comparator IC? Their comparators are exactly the same.

The unused comparators must be turned off.

 

Good to see you Austin. We never finished our convo about the transistors. Do you have any thoughts on how to change the D Flip Flop with the comparator?

 

Your LEDs do not have current-limiting resistors so the LEDs and/or ICs might blow up if they have a high output current. Also the LEDs are restricting the voltage swing so the CLOCK voltages are not valid.

Why do you use one quarter of a big LM339 quad comparator IC instead of one half of a little LM393 dual comparator IC? Their comparators are exactly the same.

The unused comparators must be turned off.

Alright, I have the LED's on resistors now...

Not sure what you meant by this: "Also the LEDs are restricting the voltage swing so the CLOCK voltages are not valid." Can you please explain?

I am simply using the LM339 because its the only chip I have

Okay, so connect the other comparators to ground to disable them?

 

WHERE IS YOUR SCHEMATIC?????
Resistors on the LEDs? In series? in parallel? 1 ohm? 1M ohm?

Since you connected an LED directly to the output of the comparator then the output is held to the supply voltage (7.5V) minus the voltage drop of the LED (maybe 2V for a red LED) so the output can go as low as 5.5V which is supposed to be a logic low (should be at most 2.5V) to feed the clock input of the flip-flop IC.

Connecting both inputs of a comparator to ground does not always disable it.
Instead connect one input to ground and connect the other input to the supply voltage.