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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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 ...
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2 votes
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88 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 ...
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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 ...
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287 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 ...
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1 answer
159 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 ...
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388 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 ...
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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 ...
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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,...
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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 ...
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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 ...
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2 answers
182 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-...
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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. ...
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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 ...
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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 ...
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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 ...
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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 ...
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2 answers
389 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 ...
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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 ...
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107 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 ...
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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 ...
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2 answers
457 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 ...
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3 votes
1 answer
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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 ...
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1 answer
930 views

Want to replace push-button with IR receiver

In the diagram below I want to replace that push-button switch Sw1 with IR receiver, I tried a lot with different combination with IR receiver and tried with transistor but I failed, so, please how ...
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Toggling 9A with ATtiny85 single-button-latch

I'm trying to use a nice one-button On|Off latching setup on ATtiny85. See for details the last one of these four: http://www.technoblogy.com/show?VOO In a low-power set-up on my breadboard this is ...
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1 vote
1 answer
131 views

3V Soft latching switch

I apologize if this has been asked before but the answers I found are all over the top for this simple latching application. I'm looking for a very compact solution: 1) 4.5 volt dc, 3 stacked hearing-...
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3 answers
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Persistent Mechanical Feedback

I am looking for a device (preferably in a small form factor) that can provide feedback for the user even after the power has been removed from the PCB (No, I don't want a battery powered solution.). (...
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1 answer
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Need a modified S-R latch

I have a comparator output who is normally high and goes low from time to time. I need a latch which will change its output from high to low when the comparator's output change to low (and keep it ...
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1 answer
109 views

Latching power button with force-off

There's been a lot of soft-latched power switch circuits discussed here and elsewhere on the internet. However, I can't wrap my head around how to implement the following requirements: Battery ...
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0 votes
2 answers
591 views

Dual Coil Latching Relay with LEDs - Opposite LED Triggers on Trailing Edge

This is my first time using dual-coil latching relays (Kemet EC2-5TNU), and I'm running into some strangeness when breadboarding out the below circuit: The coils switch without issue when sending a ...
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2 answers
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Latching Switch Pinout

I'm planning on incorporating a latching switch into my design: https://lcsc.com/product-detail/Electrical-Switches_XKB-Enterprise-XKB8080-Z_C318860.html I also found the corresponding datasheet: ...
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Latching relays connected in parallel not working as expected

I have a project I'm working on where I need 4 relays to open when power is applied to the board and close when power is lost. I need to use latching relays to conserve power as the device could be ...
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1 answer
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How soft latch power switch in this specific circuit is possible?

I am trying to understand the soft power switch operation of a LED lamp I dissembled. The circuit of the lamp is depicted below. The switch S1 can be considered as a momentary on switch (SPST). The ...
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2 votes
3 answers
631 views

Circuit to turn microcontroller on when reed switch state changes (to monitor door lock state)

I'd like to build a circuit that provides power to a microcontroller (ESP8266 in this instance) when a reed switch is changed from closed to open AND when changed from open to closed. This is to be ...
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1 vote
1 answer
500 views

momentary switch latching circuit

I'm very new at all this and hope you will have patients with me, I'm trying to use this circuit diagram to turn a momentary switch into a latching switch, I though it would be straightforward but ...
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1 answer
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Voltage reducer on a latching circuit

I have two circuits, a latching circuit and a simple 12 VDC to 5 VDC circuit using a 7805. I would like to combine these two circuits if possible. The voltage source would be a 12 VDC battery. When ...
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1 vote
3 answers
1k views

Is there a circuit simulator out there that has latching relays?

Okay, I'm at my wits end with this one. Having tried a dozen or so free/semi-free circuit simulators, I can't find any that include latching relays. This surprises me as they're one of the most common ...
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2 votes
1 answer
2k views

Latching power with LDO enable pin

There are lots of examples of latching circuits that use a single momentary push-button to turn on/off a circuit by combining two or more transistors. Some examples are: Simple soft power latching ...
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2 votes
2 answers
216 views

Electrically toggle-able switch?

I'm wondering if a switch exists that fits this functionality I imagine: The user would depress the switch, it would latch and stay depressed. Once the product completes its function, the control ...
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-1 votes
3 answers
678 views

MOSFET switching with 5V but latching ON with 12V

I am having an issue with a control signal. I have a CEP50P03 P channel trench MOSFET that is supposed to switch a 12v power supply. I am having an issue I can not figure out. When I power the ...
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1 vote
1 answer
279 views

Transistor latching circuit

I have made the following circuit from a few online sources, it is very basic but uses two NPN transistors to make a latching circuit that toggles when either push button goes to ground. My Falstad ...
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2 votes
1 answer
430 views

making an automotive "dizzy" switch with using a latching relay

My engine builder wants me to be able to turn my car over without it starting to pre-oil the motor due to a remote oil filter. The car needs to be wired so that the coil will not have juice until I ...
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1 vote
2 answers
350 views

What's happening to this 2N3906?

I'm creating a soft-latching circuit for my project, using a 2N3906 PNP transistor and an N-Channel IRLZ44N MOSFET. The circuit is fairly simple; Once switch one is pressed, it brings the gate of the ...
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2 votes
1 answer
181 views

Using two momentary switches to toggle LED

So, this circuit should (in theory, at least) turn the diode on when ON button is pressed, and turn it off when OFF button is pressed. It doesn't though. The diode is powered on at the moment where I ...
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2 votes
1 answer
401 views

Can we apply a longer pulse to latching solenoid than its rating?

I've a 6-12V dc latching solenoid, which needs 60ms of pulse to set it to on/off. I'll be using a microcontroller to generate the pulse. I've following questions. What if the generated pulse is ...
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1 vote
1 answer
357 views

Latching switch to single pulse circuit? (monostable multivibrator with 555?)

I am looking at using a latching switch (SPDT) to momentarily connect two pins. This is for a power button for a raspberry pi, so to power the machine from a hold state you have to momentarily short ...
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1 answer
1k views

Latching switch, momentary pulse output when switching on

I'm really struggling to find a simple circuit that'll give me a pulse (~1s) when switching the circuit on. The latching switch can't be changed and already controls other circuits, and the new module/...
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2 votes
3 answers
405 views

Latch-Up in CMOS-Devices

I recently read something about the latch-up effect in CMOS-Structures but I don't understand why are MOSFETs affected by this effect. I understand that high currents through the source-drain path ...
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4 votes
3 answers
2k views

Simple soft power latching circuit for a microcontroller

I'm building a simple device with a microcontroller and I'd like to be able to turn it on and off using the "hold a pushbutton for 2 seconds" trick that is found on so many consumer devices nowadays (...
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0 votes
1 answer
238 views

Turn off circuit using microcontroller signal

I want to turn off this circuit using micro controller signal to base of Q4 transistor. Can I use the same transistor model for Q4 as for Q3? I'm attaching the picture of schematic from Proteus ...
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0 votes
2 answers
1k views

How to wire latching SPDT relay using proximity switches without relay hanging

I have a hydraulic-driven piston pump that I designed and built. I need a way for the pump to automaticlly go up and down. I wired it using a SPDT relay and a 3 wire PNP NC (normally closed) and ...
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