Need of circuit for sense voltage

Thread Starter

Dzoro

Joined Feb 1, 2019
156
I need a circuit that when senses a pulse of voltage from 1-5 v dc doesn't matter how much to give continuous output and when senses another pulse to turn off.
Is that possible to do with some simple circuit
 

danadak

Joined Mar 10, 2018
4,057
1) What is the pulse width and repetition rate ?

2) Resolution you want in the measurement ?

3) Absolute accuracy of measurement ?

4) What do you do withe the measurement data ?

5) Turn key out of the box solution or design from scratch ?


Regards, Dana.
 

MisterBill2

Joined Jan 23, 2018
7,011
YES, definitely possible. In fact, that function is part of a product that I designed several years ago. Easy to build, does not need calibration , and it does not draw much power. Also, not expensive to build.
It will switch on with the first pulse, off with the second pulse, on with the third, and alternating as long as the pulses keep arriving. If you want any other action it gets more complicated.
 

Danko

Joined Nov 22, 2017
989
I need a circuit that when senses a pulse of voltage from 1-5 v dc doesn't matter how much to give continuous output and when senses another pulse to turn off.
Is that possible to do with some simple circuit
Like this?
upload_2019-2-17_8-52-4.png
EDIT:
Name of CD4013 pin , connected with collector of Q1 is CLOCK.
Not used inputs of U1 should be tied to GROUND.
 
Last edited:

Thread Starter

Dzoro

Joined Feb 1, 2019
156
Yes buti don't have 4013 can i use 4747
YES, definitely possible. In fact, that function is part of a product that I designed several years ago. Easy to build, does not need calibration , and it does not draw much power. Also, not expensive to build.
It will switch on with the first pulse, off with the second pulse, on with the third, and alternating as long as the pulses keep arriving. If you want any other action it gets more complicated.
Can you sent a circuit
 

djsfantasi

Joined Apr 11, 2010
6,805
You should be able to use the 7474. I’d tie the Preset and Clear to ground since they are not being used. You don’t want to leave them floating.
 

djsfantasi

Joined Apr 11, 2010
6,805
Hi djsfantasi,
Preset and clear should be tied high as they are active low signals on a 7474 (On a 4013 they are active high.)

Les.
Thanks, Les! The futurelec page wasn’t clear to me on that point. I checked another datasheet.

The pinout diagrams didn’t indicate these pins were active low. I would have expected bar-CLR or bubble-CLR
 

Thread Starter

Dzoro

Joined Feb 1, 2019
156
On danko's circuit what is the name of the input pin that goes from tho colector of the seconf transistor
 

MisterBill2

Joined Jan 23, 2018
7,011
My design was intended to detect and trigger on much smaller pulses, so it used 2 stages of op-amp, each stage had a gain of 1000. So yes, the two transistor amplifier should be adequate. Mine used capacitor coupling so ambient DC or DC drift did not cause problems.On the CD 4013 all unused logic inputs should be tied low, on the 7474 clear and preset are active low. I never used TTL very much, CMOS is much easier, and much lower power.
Was the continuing alternat action acceptable?? Or did the TS just want on once then off?That gets a bit more complex.
 

MisterBill2

Joined Jan 23, 2018
7,011
For power on reset with a CD4013 dual FF, use a 10K ohm resistor to negative supply, from the reset pin, and a 0.01mFd capacitor from the supply positive to that reset pin. You might need to experiment with values, it depends on supply voltage rise time at turn on.
 

djsfantasi

Joined Apr 11, 2010
6,805
For power on reset with a CD4013 dual FF, use a 10K ohm resistor to negative supply, from the reset pin, and a 0.01mFd capacitor from the supply positive to that reset pin. You might need to experiment with values, it depends on supply voltage rise time at turn on.
The TS has already stated that he cannot use a 4013, as he doesn’t have access to one. He did have a 7474. Danko provided a circuit that used a 4013 as a T flip flop. It could be implemented with the 7474 which he had.
 

crutschow

Joined Mar 14, 2008
25,417
So the power-on reset for a 7474 would be just opposite a 4013, with a 10kΩ resistor from the Reset input to the positive supply, and a capacitor to ground.
I would use at least a 1μF cap, if not larger, to insure a good reset for a possible slow power supply start-up.
 
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