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Hi guys,

I want to make this JK Flip Flop work based on in its input from the transistor and the photodiode. The photodiode activates based on the LED glow in the circuit. Now, Im not getting the JK FF to work based on these readings. Can anyone help?

https://www.circuitlab.com/circuit/3j2374/resetter/

Sorry but your circuit has several errors.

Some stuff that may help you understand:

1) How a photodiode works;

2) How to use it;

3) How to build a simulatable circuit in CL using it.

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/photdet.html

http://en.wikipedia.org/wiki/Photodiode

https://www.circuitlab.com/forums/optoelectronics/topic/rc8vh32k/photodiode/

https://www.circuitlab.com/circuit/tne4sa/photodiode-receiver-01/

Note that logic devices (Digital Elements) in CL have hysteresis at their inputs:

https://www.circuitlab.com/docs/circuit-elements/#digital

Most real devices do not.

CL's use of hysteresis will give misleading results compared to a real circuit because real devices will not switch cleanly with slow edges whereas the same edge speeds presented to a logic device in CL will appear to switch cleanly.

The use of hysteresis may also produce pulse width distortion on input signals with asymmetric rise and fall times.

It may also give misleading propagation delay information.

Hi thanks for the reply.

Basically, I just want to capture the light emitted from the LED to "Run" the photodiode. Based on the values, I want to trigger the outputs of the relay. Basically, when the photodiode is ON, the relay should be closed allowing the switch to turn ON and vice versa when the LED is OFF.

From you links, its clear to me that you can't just connect a LED and a Photodiode and expect it to work. The link you provided contains a circuit I believe is an interface?

I understand what you want to do.

You have to understand some basic electronics: about how devices work, which way round they have to be connected to operate and the circuitry that needs to go round them to make a functioning circuit.

You also need to understand the difference between:

a) drawing a circuit diagram that represents how you connect up physical components to make a circuit, i.e. a passive circuit diagram or schematic;

and

b) creating a schematic that can simulate the detailed operation of your circuit, i.e. an active simulation schematic.

As I said earlier, your circuit has several errors.

i) V4 has no series resistor to D1;

ii) Q2 is permanently off;

iii) D3 is the wrong way round;

iv) the circuitry around D3 is wrong to do what you want in terms of driving suitable signals into a 5V operated JK flip-flop;

v) you need to be aware that CL digital elements only operate with a 5V input and output swing.

iv) your diagram is harder to read than it needs to be because you have drawn the supply rails in a non-standard way.

Sorry but before you go any further, you need to learn more about electronics:

http://www.kpsec.freeuk.com/study.htm

https://www.circuitlab.com/forums/basic-electronics/topic/bf37fy6t/some-useful-learning-resources/

and if you're serious:

https://6002x.mitx.mit.edu/