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Questions tagged [latching]

A circuit or component that maintains its state after being activated (e.g. a latching relay which only requires power to change its state, then maintains its contact position even without power applied to the coil).

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Using a Latching Button for Car Hazard Lights with LED Indicator

I'm attempting to learn more about electronics with this small project I am using a latching button . I connected the button to the ignition wire of the car because I want the LED to stay on. My ...
jminhal's user avatar
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Is there something wrong with this power-on latch circuit?

I am analyzing an electronic device that has an MCU and the following characteristics: it is powered from a 3.7 V Li-ion battery it has an on/off button that needs to be pressed 1 second to power-on ...
uz3il's user avatar
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3 answers
108 views

Lowest-power approach for latching circuit for high-wattage load

I'm investigating the lowest power approach to have a single momentary push-button switch function as an on/off switch for a high-wattage load (13.8V, max 5A)—i.e., a single push gives power to the ...
Jonathan W.'s user avatar
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Single Switch with Momentary and Latching/Hold Properties Using CMOS/Logic (no µP/microprocessor)

I am looking for a CMOS/logic based solution (no µP/microprocessor) to a momentary switching scheme I'd like to implement that involves the following scenario: 1: pressing a momentary switch engages ...
paraparabolic's user avatar
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1 answer
55 views

Comparator connection with SR latch v2

I designed a comparator that sets 12 V on the output whenever there is overvoltage on the input of the comparator (13 V from AC sin source). In my schematic, the output value of the SR latch reacts to ...
Simplifier's user avatar
1 vote
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99 views

Latch circuit to cycle power in an ATX PSU

I'm designing a system powered by an ATX PSU. I'd like it to be able to be switched on and off by a momentary switch but also to be able to be turned off by another input. The latch circuit is powered ...
DusteD's user avatar
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0 answers
106 views

Explain schematic for one-shot trigger

Can you please help to explain following schematic: How does this circuit work? What is the purpose of the diode and the capacitor?
moci's user avatar
  • 97
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3 answers
204 views

Simplify a relay based latching circuit

I have designed a relay based circuit to control main power to load. How do I simplify the circuit to have less relays, especially less double pole relays? If necesssary, transistor is also acceptable....
VvOoGame's user avatar
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1 answer
168 views

How to create a power latching circuit without to exceed the GPIO specifications of an battery driven esp32 for a zero current power consumption

I want to operate an ESP32 with a 9V battery pack. In-between there is power latching circuit which is responsible for feeding a LDO voltage regulator with power for the micro controller module (ESP32)...
playmobox's user avatar
  • 105
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1 answer
48 views

Level shifter: clamping (input+VccA) when input and VccA are powered from same signal

I'm currently testing a PCB I designed, and found out the following circuit don't work properly: the SYS_EN signal is connected to a 1.8V rail through a 10k pull-up resistor. TXU0101DRYRU5 is a level ...
Sandro's user avatar
  • 7,705
2 votes
1 answer
135 views

Soft latching power circuit stops working after heating

I implemented the below latching power circuit (can be found here https://circuitcellar.com/resources/quickbits/soft-latching-power-circuits/) that has 1 button to turn the circuit on and is turned ...
ruben's user avatar
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1 vote
3 answers
117 views

Latching comparator always starts at latching position

I build a over-current protection circuit using a latching comparator, below circuit diagram is the simplified version (without the current limit circuitry): simulate this circuit – Schematic ...
ElectronSurf's user avatar
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3 votes
3 answers
216 views

Is there any such thing as a tristable, quadristable, etc. multivibrator?

The title says it all. Is there a discrete circuit that can produce 4 different outputs based on a single tactile switch click? I'd like to do this with either a discrete design or a 74373 since ...
Aaron Butkovich's user avatar
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1 answer
43 views

How to make latching valve turn to close orientation when power fail when controlling it with H bridge of MOSFETs?

I am making a circuit which controls a latching valve this valve is going to be controlled with 2 pins from my MCU. The valve must turn to the close orientation when power fails either from battery or ...
Alji2124's user avatar
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2 answers
198 views

Emergency stop behavior - state of normally open switch when activated

I am using and emergency stop in an application. It is a push button with a twist release. I have the main circuit connected to the normally closed side and a detection circuit wired to the normally ...
Siva's user avatar
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2 answers
87 views

Power latching circuit issue

I'm working on designing a circuit to latch power to an ATTINY85 when a button is pressed, then turn the power off when the button is held, but for some reason, the below schematic is not working. ...
QuantumPhysGuy's user avatar
1 vote
1 answer
117 views

LDO self-latching circuit review

I am putting together a latching circuit and just want to make sure I am not missing something obvious that would prevent this from working. Circuit: Note: the actual LDO in the design is XC6701B502PR ...
Zygis's user avatar
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2 votes
1 answer
622 views

Help identifying 6-pin SMD components with 46 L code

I am looking for the SMD below. Code "46" and vertical "L". It is used in a latch circuit and could be a NAND gate or equivalent, something like a flip-flop circuit. Here is the ...
user2053949's user avatar
0 votes
2 answers
84 views

Does this latch have a name?

I'm looking for a circuit like: Where, on the rising edge of any input, the corresponding output latches on and the rest of the outputs turn off. Sort of a mutually exclusive selection latch. Does ...
Jason C's user avatar
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0 answers
146 views

Transistor Latching Momentary Switch Help

Attached is a circuit for two "latching" transistor circuits using a momentary switch to toggle a relay. Switch 1/ Relay 1 works perfectly; toggles on/off as it should. Switch 2/ Relay 2 ...
mbmrsnctdy's user avatar
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1 answer
113 views

Is this circuit correct and safe to bypass my latch circuit, turning on the load every time I connect it to 5V?

I have this working on/off latch circuit below that works on a 8.4V battery. I can charge and bypass the battery when I connect the circuit to a 5V charger, while still providing supply to the load ...
Rodrigo's user avatar
  • 567
0 votes
1 answer
97 views

Transistors falsely latch with EMI

I have a very basic NPN - PNP latching circuit: [Sorry for the upside down image] The latch initially is off, and when the op_amp_Signal_and_latch turns on, the ...
15 Volts's user avatar
  • 707
0 votes
1 answer
131 views

Latching interval timer with positive trigger

Can I create a latching interval timer circuit with a 555 chip using a positive trigger (which is not pulsed but remains high during the timing interval and afterwards) without retriggering the timer? ...
billium's user avatar
2 votes
4 answers
1k views

Push button latch circuit - switch issue

I have built a single push on/off latching circuit as per the diagram. It runs from 12 V. It works, but the issues I have is that first, it is already on when I connect power, it should start off, ...
Grant Lee's user avatar
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0 answers
67 views

Bluetooth IC performance improves after resoldering/heating

This is a very general question and I'm trying to brainstorm and get some insight into potential issues, things to watch out for etc. Unfortunately, I can't share the schematic or the datasheet. My ...
pcbguy's user avatar
  • 83
1 vote
3 answers
1k views

Fan speed control using relays

I would like to control the speed of ac 240 vac fan using capacitors as shown in the diagram below. Since the project is an ESP32 based fan speed controller, the rotary switch in the schematic will be ...
Suresh Kumar's user avatar
0 votes
2 answers
260 views

Unstable latching circuit

I'm trying to implement a latching circuit for around 4.1V of voltage (LiPo battery). Below is the circuit: The problem is that the circuit is always on as soon as the power is applied (so even ...
Leonti's user avatar
  • 341
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0 answers
168 views

Replace transistor-latch with thyristor: is my circuit correct?

Please consider the following two circuits: On the left, is a transistor-latch using a PNP and an NPN transistor. I'd like to replace those two transistors with a thyristor, mainly to get a little ...
polemon's user avatar
  • 1,097
0 votes
2 answers
539 views

How can I quickly discharge a capacitor in a Zener on-delay timer circuit?

I have a project that requires using a delayed latching circuit. I found two circuits that I could combine, a on-delay timer circuit from TheEngineeringMindset and a latching circuit from ...
Jotaro Joestar's user avatar
2 votes
0 answers
141 views

Do I properly use Toshiba H-bridge TB67H400ANG?

I am new in this forum, so I am sorry if I don't properly ask my "question". I am a beginner in the making of circuits and Arduino programming. (first time using an H-bridge, first time ...
silvergoldengun's user avatar
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1 answer
101 views

Using a level triggered latch as a negative edge trigger for negative logic

I am a (relatively) new hobbyist and I am working on a project that uses an old video chip (v9938.) The chip is designed to use old DRAM, with a multiplexed 8 bit address bus, and *RAS and *CAS ...
user1958698's user avatar
0 votes
1 answer
4k views

N-MOSFET and NPN latching switch

I've seen many latching circuits through searching and reading some simple circuits. Most use NPN+PNP combination, some bistable ones use two NPNs, some use DPDT relays. Is the following circuit going ...
Elementronics's user avatar
2 votes
1 answer
1k views

How to make this T-flip-flop circuit

I am trying to make a T-flip-flop circuit with a relay, which would: toggle on a button press (12 V) [default state: off] allow control from an external micro-controller (optocouplers) allow ...
Jakub Smetana's user avatar
1 vote
6 answers
4k views

Latching relay but self resetting (to off) on power off?

I'll try explain my problem: I am trying to make a simple circuit that powers on when a momentary switch is pressed but then stays on until the power source (feeding the lamp) is then removed. I want ...
Jeremias Rößner's user avatar
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0 answers
110 views

ADW1205HLW latching relay heating issue

I want to take the advantage of latching relay to remove power dissipation from the circuit. I am also using ADW1205HLW dual latching coil relay but faces an issue of heating even after set or reset ...
irfan saiyed's user avatar
0 votes
2 answers
201 views

Need help on latching circuit turning on without pressing on/off button when battery is inserted

I have this latching circuit to turn on and off an MCU (ATTINY 167) and a led Driver, by using a 8.4V Lipo battery. It works fine: pressing the button turns it on and pressing again turns it off. Also,...
Rodrigo's user avatar
  • 567
1 vote
2 answers
312 views

Need help to bypass the momentary switch in this latching ciircuit (but keep using it.)

I’m using this circuit to turn on and off an Attiny167 and an LED driver with the push of a micro switch. My circuit is powered by an 8.4V battery. In the “load” part of the circuit there’s a voltage ...
Rodrigo's user avatar
  • 567
0 votes
0 answers
36 views

Get the system to turn on using a voltage source

I am working on a project where i have a momentary push button and i am using this latching circuit to toggle between the two stats, the circuit is working fine. I need to add a circuit to this one in ...
GellyHamb's user avatar
1 vote
2 answers
555 views

How to cheaply build a latching relay system to disable a circuit until power is cycled?

This is my first post here. I have an aftermarket backup sensor that needs to be disabled when I back a trailer. I want to be able to push a button to disable it, but have it be automatically re-...
idoseadoo's user avatar
0 votes
0 answers
270 views

Latching Push Button High Side Power Switch

I'm a beginner trying to design a long-push to turn off and short push to turn on push button switch. I've managed to find this design but when put into use in a 3.3V system, it does not seem to work. ...
Jing Hao Ngiam's user avatar
0 votes
0 answers
139 views

Need help in Latching ON/OFF switch

I am working on a latching on/off switch, There are many ways to do it by using discrete components. But I want to use an IC to perform that task. I found MAX16054 IC which is similar to my ...
niks's user avatar
  • 51
0 votes
1 answer
102 views

Momentary switch 12 V motor reverses game

I am trying to figure out how to control a DC motor with a momentary switch as a trigger and limit switches for stops. The trigger needs to be momentary because I need three of them in parallel at ...
Corey's user avatar
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1 vote
1 answer
90 views

7408 quad-AND with diode latching: sporadic (and undesired) self-latching at power up

As an introduction to electronics, I am still working my way through Charles Platt's Make: Electronics (2nd edition). This issue is about Experiment 21: A Powerful Combination In circuit on ...
Ad N's user avatar
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0 answers
248 views

Are there a way to join 2 I/O control lines using staircase two ways switches approach?

I am a newbie and would like to have a question and would like to have your advice. Requirements: Control 1 relay (max current is 20mA) over 1 Arduino pin (pinMode as OUTPUT and state of this pin is ...
Đặng Đình Ngọc's user avatar
0 votes
2 answers
1k views

Controlling AC relay with a single push button?

Is it possible to set an AC relay (220vac coil) ON / OFF by using a single push button (non latching) and some extra components but without the need of an additional DC supply? It doesn't have to ...
nahero's user avatar
  • 29
2 votes
1 answer
226 views

12 V relay switch wiring

I had some heated seats retrofitted to my car. I have wired them so that a 12 V ignition signal activates a relay and powers a bus bar which then powers the seats. The switches are round ON-OFF-ON ...
Ben Pettman's user avatar
0 votes
1 answer
295 views

How to add a MCU signal to turn off this push button mosfet-based latching circuit?

I’m using this circuit to turn on and off an Attiny85 and a led driver with the push of a micro switch. My circuit is powered by 7.4V battery. In the “load” part of the circuit there’s a voltage ...
Rodrigo's user avatar
  • 567
1 vote
0 answers
109 views

Can't find suitable Bistable/Latching 12V DPDT Relay

I have a 12V actuator that is controlled by a 12V programmable timer. So my pulse is either power or no power. I am using a regular 12V DPDT relay which works fine. However, I would like to use a ...
ToWi's user avatar
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3 votes
2 answers
608 views

What's wrong with this latching relay circuit?

I've been told that this relay circuit should latch. I built it and it does not. I want the LED light to stay on after the N.O dP switch is is closed and then released back to its N.O. state. Using 24 ...
Ted's user avatar
  • 31
3 votes
1 answer
888 views

Problem with SCR latching circuit

I put this circuit together to demonstrate latching properties of SCRs but I'm finding that the SCR doesn't behave as I expected it to from the datasheet values. Specifically, I found that in the ...
RichardD's user avatar