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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Some questions about a transistor latch?

Below is a latch made up of two transistors: When the base current of Q2 is increaased this increases also the base current of Q1 which in turn increases the base current of Q2 more. So by such ...
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Problem based on Latches (Sequential Circuits)

I am trying to solve the following question: I want to know: If the truth table for \$ Q_{n+1}\$ and \$\bar Q_{n+1}\$ is correct. I have found out the Reset and \$Q_{n}\$ conditions. However, I see ...
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Jellybean Radio Button logic Chip

Below is an LTSpice simulation of a 'radio button' circuilt. Ignore the bottom button, I am working on a 'reset' mechanism to unlatch any of the other buttons. The idea is that the button you push, ...
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Photocoupler to Latch Microcontroller Power Supply

I'm revising my custom arduino circuit which involves powering an atmega328p. I am using a 9V battery connected to a BS170 MOSFET. Without any voltage applied to the gate of my BS170, the battery is ...
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116 views

Aircraft Starting Mockup Display With Buzzer Question

I am stuck in the middle of building a circuit for an aircraft starting mockup that will train our students to correctly start the aircraft without accidentally re-engaging the starter and thus ...
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177 views

Latching and Momentary Combo Switch

I am looking to recreate a switch circuit I have seen on an intercom system. The switch allowed for two functions, while using one momentary switch. When the switch was pressed and emetily released, ...
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73 views

Find high current latch or use Darlington array?

Looking for best practices here. I'm building a common-anode LED matrix. I've got a current sink LED driver, and I'm looking for a latch that will provide enough current to drive an array of LEDs. All ...
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235 views

Shift register SPI control: cascading but individual latch

I would like to connect several boards to the microcontroller and send data to shift registers placed on the boards. I'm cascading all the shift registers for the data sending from the SPI. But I ...
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Why is the SR Flip flop edge enabled

I'm struggling to understand the diference between a Latch and a SR Flip Flop, I know that a latch is level activated, and the SR Flip Flop is edge activated but if the circuit is the same, why is the ...
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TTL “radio-button” using priority encoder and latch

I'm liking this site and I am not always using it to just throw a question but to develop ideas all the way. First time I did that was on StackOverflow I need JSZip and gzip for my web page, and JSZip ...
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Understanding complements on inputs

I've got a problem understanding formal writing down of complements on inputs. During my laboratory exercise I was working with a device that had D flip flop embedded in it. The goal was to ...
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22 views

Sequential NAND Based Phase-Frequency Detector output

I'm trying to understand the output of my phase detector only for a pulse that goes from zero to one. here is my schematic: (ref is Clk_ref, and Div is Clk_out, both come from an outside circuit) ...
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BJT Latching Circuit Help

I have build a latching circuit using both a NPN & PNP BJT to turn on and off an LED, as shown below: simulate this circuit – Schematic created using CircuitLab When I built the circuit ...
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105 views

Latch-based sense amplifier design using CADENCE Virtuoso 65 nm technology

I am trying to design a latch-based sense amplifier to sense about 55mV voltage difference using 65nm technolgy, it takes differential input, and should get from it differential output too where it ...
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55 views

Capacitor life hours

Working on an existing product which has had field failures. Design is a short (60ms) pulse is sent via microcontroller to activate / deactivate a latching switch. I have determined failure is due to ...
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82 views

Question about SR latch timing

I have a question about how SR latches work: To my understanding the real-world implication is that one of the two gates will receive power first and produce an output signal, and they aren't going ...
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201 views

Latching power circuit with short-to-ground switch

I'm trying to build a circuit around an existing switch that allows another component to override the switch state. (Our component is a computer and the feature we're trying to build is remote-...
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178 views

High frequency clock from clocked RS latch

We were taught that this circuit is not of much use as when CLK=1, J=1 & K=1, Q toggles at a very high rate. So suppose I want to make a high-frequency clock, can I use this? Of course, the ...
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Latch with no Vout

I'm working with the WiPy expansion board at https://github.com/wipy/wipy/blob/master/hardware/ExpansionBoard-v1.2/ExpansionBoard-v1.2_Schematics.pdf On sheet 3, there is what appears to be a latch ...
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141 views

Strange output from latch connected to comparator

I'm trying to make a latch (in ltspice), so if the comparator output (A) goes low, the latch will trigger and C will go high. C should stay high, irrespective of whether A goes high or low after that. ...
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473 views

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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109 views

Soft latch on/off button simulation

I am trying to simulated in pspice a soft latch on/off circuit but it is not working as expected, even if I double check the implementation. Can someone explain to me why the voltage on the probe is 0....
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332 views

Lowest power way to latch power supply after input pulse

Background Right now I have a circuit consisting of a Adafruit Huzzah Feather (ESP8266 board), an ADXL345 accelerometer, and an ATTiny85 (bare chip). The circuit is powered by a lipo battery plugged ...
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93 views

Memory in sequential circuit

In sequential circuit block diagram ,it is said that some outputs are again feedbacked to inputs,after storing them in memory. But,where is that memory in sr latch.In sr latch ,it is seen that the ...
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386 views

Building a D flip-flop with two D inputs using 3 S-R latches

"Use three clocked SR latches to build a D flip-flop with two D inputs (D1 and D2 ) and two clock inputs C1 and C2 . Clock C1 takes data D1 and clock C2 takes data D2 ." Any hints how to start?
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What protection measures to consider when switching many loads at the same time with shift registrers?

I'm developping a programmable load board with many of these load steps to test LDO or DC/DC converter Output. As you can see, what changes is the resistor R6 to provide other current load values....
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368 views

Latched comparator output higher than supply

I am trying to simulate the following latched comparator (the detail analysis of that circuit can be found here). At low clock frequency (200MHz), the circuit works perfectly well . However, when I ...
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213 views

IC for clocked nor RS latch

Does anybody know if I can find an IC of a NOR RS latch? It has to have a clock and does not have to have any other functions such as clear or preset. EDIT 1: It could be a D Flip Flop gated but ...
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344 views

What is the clock-to-out delay for a pulse triggered flip-flop?

In edge triggered flip-flops, the clock-to-out delay or the flip-flop delay is defined as the time between the triggering edge of the clock till the arrival of stable output from the flip flop. What ...