Questions tagged [latch]
A latch or flip-flop is a circuit that has two stable states and can be used to store state information. However latch is normally used to describe a simple storage device while flip-flop is normally reserved for clocked devices.
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Difference between latch and flip-flop?
What is the difference between a latch and a flip-flop?
What I am thinking is that a latch is equivalent to a flip-flop since it is used to store bits and is also equivalent to a register which is ...
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JK latch, possible Ben Eater error?
Is it possible that the schematic shown here is wrong?
I would expect something more like that...
It seems like that he inverted the feedback wires, but I'm quite suspicious because he made the ...
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How to turn a Latch circuit from Press-ON/Press-OFF to Press-ON/Hold-OFF circuit and how to make it auto-off when power is first connected?
I'm building a Latching circuit using 555 IC. The schematic is as follows:
The Input voltage is 12V and is used to operate the 555 IC that switches a relay coil through a transistor.
When the circuit ...
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Convert a toggle switch into a momentary response
I'm working on a project and I need to use a toggle switch to control a device that expects a momentary signal.
What I want is send a momentary pulse when turning it on and off. Ie: swith off to on: ...
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Why are inferred latches bad?
My compiler complains about inferred latches in my combinatorial loops (always @(*), in Verilog). I was also told that inferred latches should preferably be avoided....
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What is a flip flop?
There seem to be a number of different definitions of flip-flops and latches out there, some of which are contradictory.
The Computer Science text book for the course I teach is probably the most ...
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Resettable mechanical switch?
I'm looking for a mechanical on/off rocker or toggle switch that can be reset to a default state and position upon the removal of power.
The application is in a vehicle where I want the switch to ...
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How does an SR-latch actually work?
In case of a NOR SR-latch, if we make S = 0 and R = 0, then output Q = 1 and nQ = 0. I also know one important rule which is if we put high input in the set line (S = 1) then output Q goes high.
If S =...
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What is wrong with my D flip-flop toggle switch?
Until a few weeks ago, I had never drawn a circuit diagram in my life, so bear with me. I am currently trying to design (in Logisim) a circuit that acts like a toggle switch, using only basic logic ...
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What is state in a sequential circuit?
I understand that the output of a flip flop is also called as the state and the output of the flip flop before the clock pulse is applied is called as present state and after the application of clock ...
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Power circuit with a push button
In my current project, I try to connect a load rated at 5V/2A with a 5V power supply. To avoid plugging and unplugging the supply over and over again, I decided to add a push button. To turn the ...
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Why do all transistor latch circuits (that ive seen) use two transistors?
I am looking at building a transistor latch to control a relay. I don't like soldering, so a few components as possible, especially those pesky transistors.
I am looking around at various transistor ...
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Need a soft latching power on/off that starts OFF
I have spent a few days looking for a soft latching power on/off switch. I have breadboard-tested several designs, including at least these three:
Design #1
Design #2
Design #3
Testing:
I tested ...
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How to analyze S-R latch circuits?
I'm trying to understand the circuit below (from the Apollo Guidance Computer), which is two S-R latches connected together. The top input resets the output and the bottom input sets the output. But ...
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Latching power switch question
I have the following circuit (source: EDN):
I understand the basic working principle of the circuit and it works fine when it is powered from a 1.5V source.
But when I power the circuit from a 9V ...
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Circuit for childrens "electric" toy/game
Some might remember a childrens game where you have a sheet of symbols, holes in it that lead to contacts, and then you have two wires and whenever you have two symbols that match you put some cables ...
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A simple clarification on latches and flip-flops
Here are two representations of a gated SR latch (first one from my book and the second one from Wikipedia):
The part I don't understand are the S and R inputs, why are they reversed in these two ...
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Any IC similar to ULN2003A with latch or enable/disable?
I'm working on a project that uses a ULN2003A (darlington transistor array) and I need to enable/disable it. The point is that ULN2003A does not have enable/disable pin.
I think that a IC with latch ...
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How can I implement a simple, Q only, D-latch using VHDL?
I just started VHDL today and I'm the type of person that can only learn by doing stuff, so after I made some basic gates in VHDL, I tried making a simple D-latch(so no clock signal), however without ...
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Metastable state when S = R = 1 in SR Latch?
According to wikibooks, under the section SR Latch, S = R = 1 is a metastable state. The following things are mentioned under the heading
When both inputs are high at once, however, there is a ...
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Is there any way to inhibit this latch circuit from locking up at startup?
Using an opamp (in+ is fixed 4V ref, in- is a square wave 5/1V), I have an NPN-BJT in the feedback network, and this BJT acts like a latch; once the output goes "high" the BJT pulls in- to ground, ...
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Starting a latch in a known state
I have a latch, and I could use some advice on starting the latch in a known state.
I'm running some robotics off of an ATX power supply, controlled by an Arduino. The motors and such are weak and ...
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SR FlipFlop Question
I am studying Digital Logic Circuit right now and I have question to ask. I have searched lot of places in order to find this answer, however due to my lack of searching ability I was not able to find ...
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Issues with Latching switch using push button
I'm trying to make a latching power switch based off this schematic (source: EDN)
I emulated the circuit in Falstad and everything works like it should (link to simulation).
However, it doesn't ...
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Momentary to Latching Circuit with Zero Off Current
I have a project with several physical constraints so that I want to use:
1. A sealed very thin momentary switch as main on/off switch
2. 2 x AAA battery supply = 3V or less
3. Load is a small DC ...
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Why is a flip-flop also known as a latch?
I am new to digital logic design and would like to know why a flip-flop is also known as a latch?
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How to restrain this soft latching power switch from eating too much current?
I am designing a two buttons soft latching power switch for a project involving a raspberry pi, li-ion cells I salvaged from the battery of a broken laptop, and a power booster from adafruit.
I ...
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There is no 'latch pin' on MC74HC164A shift register
Unlike a 74HC595, this shift register (http://www.onsemi.com/pub_link/Collateral/MC74HC164A-D.PDF) doesn't have a latch pin. How then do I output the data stored in the registers (to something like an ...
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how to make a latching circuit with ground
I have a pump, represented by a lamp in my schematic, i want this pump to be running once i switch the Activate switch, and when ever an alarm(i have 2 different) is triggered (Alarms are ground) the ...
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How does electricity flow in this SR latch from Petzold’s Code?
I am confused as to how this circuit is complete and hence how electricity flows through it.
Petzold explains earlier in the book that the V refers to a battery connected to ground the way in which I ...
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SR latch circuit with ESP8266
I want to keep some state during a deep sleep of an ESP8266. To do this I used the following SR latch circuit:
It works well. The only change I made is that I used 2N2222 transistors.
The only ...
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How do we decide which circuit is a latch?
Will A and B always be the complement of one another regardless of
what logic gates we use in the latch-like circuit? For instance (the
two circuits shown as examples):
How do we decide whether A and ...
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Master-slave flip flop without gate delay?
It seems like a master-slave flipflop always has around a 2-gate delay between the Master and Slave sections of the flip flop. For example:
My question is what would happen if, theoretically, there ...
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Soft-latch auto-reset OFF (hold) / ON (press) button, is the schematic correct?
I'm looking to make a soft-latching interface with a single momentary push button.
Required features for my build are (edited, sorry for bad description) :
Circuit should always start in OFF ...
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Latched Logic Circuit
I'm having trouble with part of a build I have to do. I've built this circuit: \$I = A\bullet(B + C + D + E + F)\$ The \$+\$ is OR, \$\bullet\$ is AND, and I'm using 2-input OR gates. The output ...
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S-R Latch using given gates
Hi I want to know the following.
An S-R latch can be implemented by means of
a. AND, NOR
b. NAND, NOR
c. AND, XOR
d. NOT, XOR
