Dual D_type Flip Flop 1

[skeematics21]

I'm trying to design a simple circuit that detects High/Low inputs and displays pass or failure with a LEDs.
I'm currently using a CD4013BC (Fairchild) in the design as the voltage detector driving Switch mosfets that control the illumination of the Pass/Fail LEDs. The problem I'm having is that if the Input is LOW (0V) and the outut is displayed as "Fail" with the LEDs, I can reset it by Inputing a High (+5V). I only want it to reset when using a reset switch.

If the input is low, I would like the output "Fail" LED to remain lit wether or not a High voltage is set on the input. I only wanted reseted by a reset switch

 

[IRstuff]

You seem to have already alluded to the solution in your title; so what's the problem?

TTFN

 

[Noway2]

It sounds as though you are either using the Set and Reset pins for your inputs or you are clocking at a steady rate to to change the state of the FF. From the datasheet, this device is rising edge sensitive with asynchronous set and reset controls. The device does not have a clock enable line. It sounds like you may want to use a device with a clock enable control to disable further activity when a fail state has been achieved. Perhaps you could initially set the output high (set) indicating a pass state and tie the output to the enable control line. Then if you clock in a low input, indicating fail, the enable line gets deactivated and the FF will hold in the fail output state. This assumes you are using an active high enable. If your enable is active low, you would want to tie it to /Q instead.

 

[skeematics21]

The problem is that i want the Q (output) to remain at it's state no mater what the input is. I want the data stored once it's detected and only changed with reset switch.

Is that possible with this chip?

 

[skeematics21]

Noway2.... thanks!!! I'll try that and get back to you.

 

[IRstuff]

The two standard approaches are:

> Reset FF low; Tie D input high, Use Signal as clock
> Rest FF low; Tie D&Clock low; Use Signal as Preset

TTFN

 

[skeematics21]

IRstuff..Bear with me but I'm not clear on your approach.

- Reset FF low; Tie D input high, Use Signal as clock....... Use which Signal? D or Q

- Rest FF low; Tie D&Clock low; Use Signal as Preset.......... Use which Signal? D or Q

 

[IRstuff]

YOUR signal

TTFN