Change DC Logic Output to Pulse
Change DC Logic Output to Pulse
(OP)
Hello everyone....
I have a simple (I think) question. I need to change a continuous DC logic output to a single pulse output using a simple circuit or switch of somekind. I am planning on splitting the DC logic output of my circuit into two seperate leads. One lead works perfectly already with the DC out, but I need the second lead to change into a single pulse, like pushing a button once. Each time the DC out is true, I need a switch or circuit (flip-flop???) to send a single logic pulse. I would prefer to purchase something that could accomplish this as opposed to building it, but I have no idea what direction to look for a solution.... any help???
Thanks,
Scott
I have a simple (I think) question. I need to change a continuous DC logic output to a single pulse output using a simple circuit or switch of somekind. I am planning on splitting the DC logic output of my circuit into two seperate leads. One lead works perfectly already with the DC out, but I need the second lead to change into a single pulse, like pushing a button once. Each time the DC out is true, I need a switch or circuit (flip-flop???) to send a single logic pulse. I would prefer to purchase something that could accomplish this as opposed to building it, but I have no idea what direction to look for a solution.... any help???
Thanks,
Scott





RE: Change DC Logic Output to Pulse
Look for 555 timer....
RE: Change DC Logic Output to Pulse
be converted to a pulse for you don't know when the pulse
is to be sent.
Usually you send the pulse when the DC rising exceeds
a certain threshold. The circuit is : Comparator with reference voltage -- triggering a single shot.
<nbucska@pcperipherals.com>
RE: Change DC Logic Output to Pulse
RE: Change DC Logic Output to Pulse
Is it for industry use?
Is it a budget project?
For industrial use a special timer relay can make the job,
but the cost will be comparable to cheapest PLCs.
In the relay logic it may be done as follows:
- the continuous signal operates relay 1 coil,
- relay 1 switches a capacitor from charging to discharge on relay 2 coil,
- relay 2 is active until the capacitor is discharged to some voltage.
The pulse time depends on capacity and discharge current.
In reality the relay 1 contacts have to be protected by limiting the charging current (by resistor).
This determines minimum time between pulses.
Cbarn24050, not exactly.
You have to provide means to discharge the capacitor while the signal is off.
RE: Change DC Logic Output to Pulse
RE: Change DC Logic Output to Pulse
At input the transition from Low to High should make a quick pulse (Discharge time depends on RC values).
RE: Change DC Logic Output to Pulse
When a logic low DC signal is applied to the trigger input the Q output will transition from a logic low to a logic high. The duration of the pulse is controlled by the rc time constant expressed as 0.7 RtCt. If your signal input to the Trigger input of the 74121 is alogic high just use a 74704 inverter IC to convert the signal to a logic low.
Best regards, PLCSAVVY.
RE: Change DC Logic Output to Pulse
The output of the pulse is from the emitor. Put a resistor parallel to the capacitor. The length of the pulse would be from the capacitor.