Hi

I am looking for a CD4000 series IC that will take a positive pulse and the output will
go high and stay high. By the same token it should take a negative pulse and the output
should go low and stay low. I wonder if a type of flip-flop would do the job.

Juan

 

You can use any flip-flop that has SET and CLEAR functions, or what is known as an R-S flip-flop.

But you need to draw the waveforms with time and voltage scales so that it is clear what you mean by positive pulse and negative pulse.

 

Certainly such a circuit can be created, but not with 4000 series CMOS. A NEGATIVE pulse, that is, relative to the return side of the power supply , will usually result in a damaged device. 4000 series CMOS operates with positive voltages, I am not aware of any exceptions..

 

If a negative pulse means negative voltage, you will have to bias the signal into positive voltages.

 

Not an IC, but a pre-biased memory relay will do exactly that.

 

When I don't use gate all the time I forget need review.
possibly the D latch enable will work for a dedicated on and dedicated off? he does mention memory.
At high speed, a 2 channel oscilloscope could capture the green leds. A 4 channel would show the enable also.
A logic probe for slow. enable for locking the on/off state. If you build from cmos you really will understand better.

The setup of a CD4013 dual SR Flip Flop

 

Hi

I am looking for a CD4000 series IC that will take a positive pulse and the output will
go high and stay high. By the same token it should take a negative pulse and the output
should go low and stay low. I wonder if a type of flip-flop would do the job.

Juan

Hi
By negative pulse, I think you are meaning a "low going" pulse, or a pulse that starts high and falls low.
A CD4013B FF is positive triggered, but you can use an external device to "invert" the low going edge to a high going edge.
A transistor, or CD40106 inverter, or NOR, or NAND gate configured as an inverter can invert the signal. Or you can use any of these to create an SR Flip flop and inverter.

 

You don’t need any fancy flip-flop.
CD4001 quad 2-input NOR gates or CD4011 quad 2-input NAND gates would do it.

 

What is supposed to happen when each pulse teminates?
How brief are the pulses?

 

Please clarify if by negative pulse you mean a voltage that is negative relative to the power supply common?? or just a falling edge of a positive voltage?? It matters a great deal.

 

Depending on the response from the TS, and it pains me to say it, a 555 can do this.

ak

 

Hi

I am looking for a CD4000 series IC that will take a positive pulse and the output will
go high and stay high. By the same token it should take a negative pulse and the output
should go low and stay low. I wonder if a type of flip-flop would do the job.

Juan

A flip-flop would indeed do the job if you want something that takes a positive pulse and keeps the output high and similarly taking a negative pulse to bring the output low. Some options would be CD4013, SN74ABT574DWR, MC74F374DR2 and NLX1G74MUTCG.

 

Had to change my post after rereading all previous ones.

EDIT/
Is the OP by any chance talking of trailing/leading edges?
/EDIT

 

Had to change my post after rereading all previous ones.

EDIT/
Is the OP by any chance talking of trailing/leading edges?
/EDIT

Evidently a whole lot of folks ASSUME that the TS means exactly that! But if it is not, there will be a fair amount of smoke released.
There is, however, a scheme that would work that way, within limits, if a15 volt CMOS FF is used. Just connect the negative supply terminal of the IC to the negative rail and the positive terminal to the positive rail, and the reference for the pulses would be at the center of the supply voltage. Triggering may be a bit unreliable, possibly.
An addition, after my email is finally repaired (took75 hours).
Differentiate the pulses so that they will operate edge triggered logic. Then feed that result to an opamp capable of a bipolar output (bipolar power supply) THAT will work. Certainly farfrom a one device solution, though.