Questions tagged [voltage-detector]

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Detecting 220vac with optocoupler and microcontroller on lines that have capacitive coupling voltages

I'm a hobbyist, trying to instrument my heating system so that I can control a three position valve. I have an ESP8266 integrated with a DRV8825 stepper motor controller, and a no-name Chinese 220vac ...
Richard Appleby's user avatar
0 votes
5 answers
150 views

Detecting 16 V AC with a GPIO

My project involves detecting a ringing doorbell. The doorbell circuit is 16 V AC and I want a low-voltage binary signal from it. The obvious way to me is to transform that electrical signal until ...
Jonah's user avatar
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3 votes
3 answers
493 views

Window comparator to drive LED

I’m struggling to build a window comparator circuit where the output is high when the voltage is in range. I do not have access to any kind of inverter. I have tried using an inverting op-amp, but ...
FluffyMuffin's user avatar
0 votes
0 answers
59 views

How to detect voltage peaks above a set threshold?

I have a power source that will generate voltage peaks for a very short amount of time (around 20 - 100 Microseconds long). I am trying to develop an electrical circuit that will capture the peak ...
Raph's user avatar
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3 votes
1 answer
173 views

Simulating HCPL-3700 using LTSpice

I am trying to simulate HCPL-3700 using the LTSpice model provided by Broadcom. Following the application note 1004 example 1, I am able to successfully calculate the Rx value and simulate the model ...
raj's user avatar
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2 votes
1 answer
1k views

BLDC back-EMF zero-crossing detection using comparators: resistor confusion

I am building a sensorless BLDC driver development board using an RP2040 chip and I plan on detecting the back-EMF using comparators. After reading quite a bit about the BLDC phases and methods to ...
vm1988's user avatar
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3 votes
4 answers
1k views

How does this transistor-based voltage detector circuit work?

I was looking to see if there is a low voltage detection circuit that could be made without ICs. I found this circuit but with the given values and configuration I don't understand how it could work. ...
josh's user avatar
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1 vote
2 answers
191 views

Detection of mechanical relay sticking

I'm exploring new methods to find if relay contacts have been stuck together without using auxiliary contacts of the relay. while searching I find out this block circuit: at this Toshiba page as far ...
David's user avatar
  • 41
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4 answers
427 views

How to detect a sine wave signal to trigger a logic gate? [closed]

I need a way to detect a signal input and then output it as a logic high. The signal input has a 40 kHz frequency and it's a sine-shaped signal. The amplitude is not sure, could be from 12 V to 1 V. ...
jjk's user avatar
  • 123
1 vote
1 answer
169 views

Would this isolated AC peak voltage detection circuit work?

I have adapted the circuit from Michael's circuit in Efficient method for isolated detection of AC voltage without a stepdown transformer to detect on either side of the positive half-cycle peaks, ...
photon-delight's user avatar
1 vote
1 answer
60 views

Why I am seeing small voltage in the voltage display from detector?

I am using this detector to detect the brightness of an LED (powered and controlled by controller). When I use this multimeter to measure the detector output, I see the range of detector from 0-12.13V....
nyeas001's user avatar
1 vote
1 answer
120 views

Cheapest HV AC detector

I need to detect AC voltage with MCU for ensure relay health condition, the cheapest and smallest solution are most welcome. I have no hard time restrictions or noise canceling\debounce requirements (...
segar's user avatar
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0 votes
1 answer
33 views

Voltage detector with ajustable time delay in a THT package or build own simple small time delay?

For my project I need to delay the enable signal from an esp32 for a 50MHz clock by a bit - The examples I use on how to do that only ever use a BD523 with non-inverted output. For testing I want to ...
Daniel Do's user avatar
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0 votes
3 answers
899 views

Zero crossing detector output to another optocoupler

I will use the configuration below to build a zero crossing detector to connect to a PLC. I will change the output voltage to 24VDC and the correspondig resistor to 50K. The problem is that the input ...
user3177225's user avatar
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1 answer
2k views

Why is my 50-600V voltage tester able to detect 3V? [closed]

I used non-contact voltage tester to test burned out Christmas lights. It says it can only detect in the range of 50-600V. One of the strings has 40 bulbs in series and none of the lights are burned ...
RNdev's user avatar
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0 answers
378 views

How The no Contact Voltage Detector circuit work?

I saw the no Contact AC voltage detector circuit on some video on youtube and tried to make the circuit except that I wanted to replace it's led with an active buzzer with internal oscillator Problem ...
Mahmoud Salah's user avatar
0 votes
2 answers
75 views

Detecting very high voltages

I work for a plastics molding company and we manufacture containers that we need to verify do not have holes in them. I am looking design a fixture that will apply a very high voltage (about 15-30KV) ...
Victor Konshin's user avatar
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0 answers
36 views

How do I detect the output voltage of the charging controller?

My project uses Li-ion battery charger LTC4099 (https://www.analog.com/media/en/technical-documentation/data-sheets/4099fd.pdf). And S6E2DH FM4 microcontroller (https://www.cypress.com/file/224786/...
Nikeboy's user avatar
  • 63
1 vote
2 answers
276 views

Need a circuit to detect if something has gone from off-on or on-off

I'm new to circuit design but I'm trying to design a circuit for a power antenna that will send a 5 second pulse whenever it detects a a wire has gone from off-on or on-off. So far I have designed ...
Peter Walker's user avatar
1 vote
1 answer
506 views

HCPL-3700 voltage detector opto influencing DUT due to low input impedance. Pump float and controller

I am trying to monitor the state of a float in a septic tank using the HCPL-3700. The float is connected to two screw terminals on the controller panel. This float is normally-open with 120VAC ...
Maxwell Faraday's user avatar
0 votes
3 answers
805 views

Detecting very low voltage audio signal

[Note: the initial text of this thread was edited] I'm trying to do the simpliest circuit possible for muting tpa class-D amp boards (tpa3118, 3116, and so) in the absence of input sound/music - yeah,...
user243993's user avatar
0 votes
2 answers
907 views

Defect LED detection for car lights

The schematic beneath is a new project of me. The theory behind this is: My car has a very fool proof bulb failure detection and warning system. CANbus proof LED bulbs can't fool the car and just a ...
htevents's user avatar
0 votes
1 answer
70 views

Automatic watt/volt/amp switch

Google has failed me so I'm asking here. I am looking for an automatic switch, which will change state depending on the number of Watts/Volts/Amps flowing through the circuit. As an example: When ...
Illidanek's user avatar
  • 103
0 votes
2 answers
45 views

Signal Superposition and divider?

I am all out of MCU pins and would like to add a voltage sense function. This will only be necessary when the device first starts up. I have a somewhat sensitive signal already connected to my ADC, ...
Hackstaar's user avatar
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1 vote
0 answers
101 views

Can I extend the allowed Vin range of a voltage detector IC with a simple zener shunt regulator?

I'm trying to solve a particular corner case in the behaviour of a system I designed. The issue can be boiled down to this: I don't want a particular LDO to operate if it's input voltage is below 4V (...
anrieff's user avatar
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0 votes
1 answer
90 views

Fast mains outage detector

What is the fastest mains outage detector at <1ms? Anything that uses a 12V DC adapter or a mechanical relay is not an option for me because it has a long delay. Is there an AC driven static/solid ...
selnet's user avatar
  • 11
0 votes
1 answer
102 views

Power consumption in voltage detector

I am quite new in embedded system and circuit design. I have designed a system in which I have to add voltage detectors. I need to find the accurate power that the detector can consume in each cycle ...
Quratul Ain's user avatar
0 votes
1 answer
145 views

Open drain voltage detector NCP301LSN45T1G

I have to use a voltage detector to detect a decrease in voltage to reset a microcontroller. I have found the NCP301LSN45T1G to do this. But I have a question about the Reset Output current (N-...
geek225's user avatar
  • 197
0 votes
1 answer
334 views

Voltage tester pens

This is my first post here so please have patience with me: I understand, there are at least two kinds: a direct contact tester which basically is a neonnlight, and a resistor a non contact AC meter ...
AbsolutelyFreeWeb's user avatar
1 vote
1 answer
578 views

How do I make a discrete voltage detector?

I would like to design a circuit which has outputs LOW when the voltage it is connected to is below a threshold, like 3.3V. There are some ic's you can buy to do this, but I would like to make my ...
Eric Navarrete's user avatar
1 vote
1 answer
2k views

How do non contact voltage detectors work on open circuits

I’ve seen how people use non contact voltage detectors to check whether or not a socket’s live wire has power. Non contact voltage detectors take advantage of capacitive coupling that occurs in AC in ...
rr1303's user avatar
  • 481
1 vote
2 answers
4k views

Why does a non contact AC voltage detector detect voltage on a DC line that is not flowing

I have two non contact voltage detectors (Klein and Greenlee) ..both are rated to detect AC voltage with a sensitivity range from 50 to 1000 V. I used these detectors on 9 different cell phone power ...
user197770's user avatar
3 votes
3 answers
2k views

Flip a Schmitt-Trigger when current flows through a Zener diode

I am trying to design a circuit using an intermitent power source (a bicycle hub generator), which is rectified and filtered, and regulated at 6,8V. Now I want to "detect" when the power source is ON ...
heltonbiker's user avatar
1 vote
3 answers
1k views

Non contact (contactless) AC or DC detection?

I'd like to detect AC or DC current (not the current level just nothing or something => ON/OFF) in a wire with a (DIY) sensor just in contact (glued) with the wire plastic insulator. At the end the ...
E.Racineux's user avatar
1 vote
2 answers
3k views

24 VAC Detection Using Optocoupler

I have been using an HCPL3700 to detect 24VAC, but they are large and relatively expensive. I have tested the design shown in the figure (AC input to the diode, and measuring output collector-emitter ...
T2JSplode's user avatar
3 votes
1 answer
1k views

Detecting power loss in a microcontroller to save context

I am trying to detect sudden power loss in my micro controller to save its state before the MCU dies. I have been thinking to utilize one of my GPIO pin to detect the supply voltage and use a large ...
Zac's user avatar
  • 432
0 votes
2 answers
249 views

detection of dc pulse

following is a pulse which i obtained from a circuit and i want to get a count when the pulse is initiated. My circuit is to detect a lightning and i obtain this pulse in our high voltage laboratory ...
Ayesha's user avatar
  • 33
0 votes
0 answers
85 views

Measuring direction of a three phase motor (400VAC, 50 Hz) within a 5V-circuit

I've got a lot of motor controller boards, without the actual motor, and I'm interested in measuring at the output terminals (U,V, W) to see if there's any voltage. This to just check rudimentally if ...
bos's user avatar
  • 950
0 votes
3 answers
96 views

How to find status (on/off) of any applicance ( light, fan, etc.) connected to an electrical circuit

There are 4 appliances connected to an electric circuit, how to determine which applicance is on/off and pass that information to an electronic device in binary form. The idea is to make an ...
Shreyance Shaw's user avatar
5 votes
1 answer
2k views

Detect Sound From Google Chromecast Audio

Recently I have brought a Google Chromecast Audio and the audio signal is fed directly to my stereo. I want to detect on the sound level in order to turn the stereo on and off. Then I successfully ...
Jens Joachim's user avatar
0 votes
0 answers
62 views

Controlling NMOS

Can I control a NMOS (don't look the reference in the schematic) to shutdown a LDO with a voltage detector like so ? Or is there missing something? simulate this circuit – Schematic created ...
Tagadac's user avatar
  • 453
1 vote
5 answers
243 views

Simple, low power way to buffer a 500mV threshold signal to an open collector output?

I have a signal that is 0-500mV when low and 600-900mV when high. I'd like to buffer this signal to an open collector output. The output must withstand a maximum of 3.3V be capable of sinking 60uA. ...
bigjosh's user avatar
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0 votes
1 answer
773 views

Will this circuit suffice for low battery detection for any microcontroller?

I'm making a major digital circuit powered by two 3.6 volt cordless phone NiCD rechargeable batteries, and one thing I want to include is a low battery detector. To protect the rest of the circuit ...
user avatar
3 votes
1 answer
395 views

Detecting presence of a voltage without drawing too much current

I am working on a microcontroller project for a garage door opener. Rather than supply additional magnet+reed switches or other kind of detectors for sensing whether the door is full-open or full-...
jose can u c's user avatar
2 votes
2 answers
817 views

Separating Phase and Neutral in AC?

I need determine if a cable is connected to a wall-socket (230V) on the other end with a timer in-between. 230VAC---TIMER---CABLE Depending on how the timer is ...
Niclas's user avatar
  • 21
3 votes
2 answers
2k views

Efficient method for isolated detection of AC voltage without a stepdown transformer

What is an efficient method to detect the presence of Line AC power in an isolated method? My first thought would be to use an optocoupler, but in order to do that, you need to supply the current ...
Eric Johnson's user avatar
3 votes
1 answer
197 views

Why can't a control unit detect this 12 volt signal while my multimeter can?

I work as a contractor installing stop request signs on busses. The stop request sign is basically a device that illuminates when a rider pulls the stop cord. When it is pulled, 12v is sent to the ...
David Tang's user avatar
1 vote
1 answer
373 views

How to detect a signal if it is greater than VDD or smaller than 0?

I need to detect a signal if it is greater than VDD or smaller than 0. I can't use comparator because the input signal is outside of common-mode input range and I have only one power supply VDD. Is ...
emnha's user avatar
  • 1,619
2 votes
1 answer
383 views

Detecting when AVR ICSP header has a cable connected

I have a bunch of Atmega16A MCUs laying around so I want to use them with an ESP8266 to relay temperature and such in each room of my home to a server. The thing is, if I need to update the firmware ...
Funkyguy's user avatar
  • 3,588
0 votes
1 answer
230 views

Is there anyway to detect lowest voltage of a signal like capacitor and diode do for the high one?

Is there any simple (not the best one) way to detect the lowest value of a signal, like a diode and capacitor detect the peak value, I want to do it for detect the lowest value of a signal.
Pulse9's user avatar
  • 499