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Questions tagged [low-voltage]

Low voltage refers to voltages in a range from 1) 50–1000 Volts AC (root mean square) and 2) 120–1500 Volts DC according to standard IEC 60038 of the International Electrotechnical Commission.

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Troubleshooting a Low Voltage Cutoff (LVC) Circuit for Overdraining Prevention

I am attempting to design a Low Voltage Cutoff (LVC) circuit to safeguard against overdraining my 12V rechargeable battery. The objective is to halt circuit power once the battery voltage drops below ...
Karampistis Dimitrios's user avatar
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1 answer
64 views

Millivolt logger with high sampling rate [closed]

I'm trying to find modern components for a design that would be able to record millivolt range samples at a high sampling rate (~30 kHz) for ~1 hr interval. Key components I can think of thus far are ...
Keiland Cooper's user avatar
1 vote
1 answer
45 views

Low power consumption/leakage tips and tricks (input NC magnetic reed switches)

I have an ATtiny412 that has 2 pins (PA1, PA2) set as internal input pullups. These 2 pins (PA1, PA2) sense magnetic reed switches with the NC setting. GND is active when closed on these switches. The ...
Jonas's user avatar
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1 answer
37 views

Need help connecting 10 LED USB powered lights to one power source [closed]

I need help to connect 10 LED string lights into single plug. I wanted to make sure I have enough power, but not burn out the lights.
Nick 's user avatar
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Symmetric PCh and NCh MOSFETs for variable resistors

I'm wanting to build a variable voltage-controlled resistor. The resistor would be in series with a 200 uA AC current source and need to be controllable between 1-20 ohm. My current plan is to take ...
Mekala's user avatar
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1 vote
1 answer
68 views

Voltage stabilizer or voltage protection device for irrigation setup [closed]

I have an irrigation setup in a rural area with voltage fluctuations. The irrigation setup consists of a Hunter X2 Controller powering a pump start relay which in turn runs a 1.5 HP submersible motor ...
tushar_p's user avatar
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1 answer
41 views

A stable very low-voltage reference generator (a very low-voltage LDO design idea) [closed]

Essentially, I have a voltage which varies between 0.15 VDC to 0.25 VDC, and this feeds into a system whose output is varying because of this variation at the input side. This is summarized in the ...
Debugger_Op's user avatar
7 votes
2 answers
2k views

LED Fails to illuminate, what am I not seeing in my configuration(s)?

I'm working on a super simple circuit, I want to light the LED. Power Source 1: 5.5v from 9v battery through breadboard power supply module Power Source 2: 5.5v from lab bench PSU LED Info: Vf - 3v to ...
Riana's user avatar
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2 votes
0 answers
69 views

Philosophy of safety by Double Insulation

In a Class I appliance, when a fault occurs that brings dangerous voltage in contact with accessible conductive parts, the installation wiring fuse or GFCI will not only shut down the dangerous ...
tobalt's user avatar
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1 vote
1 answer
83 views

Op-amp not increasing amplitude of signal

I was doing some LTSpice simulation with an op-amp to amplify a 1 millivolt 40 kHz sine wave. However, in the output signal, it had just raised the voltage of the whole waveform, it decreased the ...
epicMan123's user avatar
1 vote
2 answers
86 views

Reading voltage across Christmas light wires, multimeter shows erratic readings

I am attempting to splice a simple on/off switch into a strand of Christmas lights. Previously, I separated the two wires and cut open the one marked with dots, expecting it to be the positive/live ...
Riccardo Orlando's user avatar
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60 views

Asking Question about Low Voltage Transistor, MOSFET or op-amp for a Conditioning Circuit

Which transistor, MOSFET or op-amp, can I use in place of the 2N2222 NPN transistor to turn ON the circuit for the lowest input voltage in mvolts. Explanation: I've obtained a voltage signal from a ...
Ubaid Ullah's user avatar
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1 answer
95 views

Low Voltage LED Runway lights Part 2 [duplicate]

I will use 10 g 2 strand direct bury low voltage wire I believe that I need to run a loop and I am considering adding another 600 watt transformer to the opposite side of the runway that will turn ...
Hermannator's user avatar
1 vote
0 answers
60 views

Electrical Standards for Exposed DC Connections

We are trying to make a slide lock connection between two parts and thus need to have some sort of connector between them. I am wondering if anyone is aware of a IEC standard relevant for connecting a ...
Explorex's user avatar
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2 answers
116 views

If the current through a welder is hundreds of amps to melt metal, how does the welder circuitry cope

A pretty simple question but i have no idea. My logic is if the current is so high where something as low resistance like a metal slab can be heated to melt. How on earth does the components in the ...
George kirby's user avatar
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2 answers
98 views

Single pulse generator

For my 10V model train's signals and switches I need a ~500msec power pulse (AC; low Amp). I already have an electronic switch that provides power when triggered. However, the power should be brief, ...
Ben van der Pluijm's user avatar
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1 answer
74 views

Is there a way to tell if I have MLV or ELV transformers driving my 12V 50W LEDs? [closed]

Is there a way to tell if I have MLV or ELV transformers driving my 12V 50W LEDs? I want to dim a small row of ceiling downlights with 3-Way Lutron Maestro dimmers. The actual fixture is a Nora NL-301 ...
Bob's user avatar
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0 votes
1 answer
59 views

1950s Era primary and secondary low voltage intercom system [closed]

I have a 1959 low voltage panel right next to my 120 volt panel in my laundry room. This panel controlled an Old intercom system as well as the lights for the house. Inside of the panel there seems to ...
Maile Latu's user avatar
0 votes
0 answers
127 views

Variable voltage control from an ESP32

First, the background context: I have a pair of these TCS-300 landscape lighting controllers which have a cloud-only control interface, which cannot be integrated with my local home assistant. My goal ...
Wez Furlong's user avatar
2 votes
2 answers
84 views

Looking for Low Noise High Shielding BNC [closed]

I am doing some research looking at low voltage signals, on the order of 100nV. Due to the usage of other equipment such as a current source there is spurious pickup noise in the cables carrying this ...
Cillorn's user avatar
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4 answers
119 views

I have a solenoid rated at 24 volts AC, but at a trickle voltage of 1-9 volts the solenoid stays pulled in when it shouldn't be

I have a solenoid that pulls in at 24-30 volts ac to control water flow. It opens at 24 volts ac, but stays pulled in at a trickle voltage of .75 -1.0 volts. How can I stop this from happening?
doctortom44's user avatar
2 votes
1 answer
183 views

What assumptions are made by UL when they equate 30Vrms to 60Vdc for LVLE circuits?

UL defines Low Voltage Low Energy circuits as "A circuit involving an alternating current voltage of not more than 30 volts, rms (42.4 volts peak) or a direct current voltage of not more than 60 ...
jrive's user avatar
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2 votes
1 answer
134 views

Simple LED Low Voltage Indicator for Li-ion cell (3.3 V threshold)

I'm working on a handheld project that runs off a single cell 3.7V Li-ion cell. I would like to trigger an LED to turn on when its voltage drops down to 3.3 V. I have seen other answers with a TL431 ...
user346278's user avatar
0 votes
0 answers
112 views

High swing (Low-voltage) cascode current mirror pole

I have been trying to figure out extracting the exact derivation for the poles, I am only struggling with figuring how the author got pole 8. I am using the small signal for the high swing cascode ...
serdude's user avatar
2 votes
1 answer
49 views

How to achieve the lowest noise configuration from a differential setup

I want to be able to capture a differential output from a shunt resistor. The shunt resistor differential voltage will range from 2.5mV to 50mV at 50Hz. My initial idea was to send this signal through ...
JoeyB's user avatar
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1 vote
1 answer
136 views

How to design an accurate (1 μV error) meter

I want to design an accurate LV meter. The range is from 2.5mV to 50mV both AC, with a 5uV accuracy. This comes from a shunt resistor that is connected to AC main (230V AC). Hence it will go below 0V. ...
JoeyB's user avatar
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0 votes
1 answer
95 views

Can not get maximum torque (stall torque) when current reach peak current

I am using FOC to control torque of 220V AC servo (SPMSM) with 36V power supply at low speed (100-200rpm). I tested with some servos (different manufacturers) which has specs as the below table. But I ...
Breezehn's user avatar
2 votes
3 answers
173 views

I need help designing a low voltage DC to AC circuit

Can anyone help me design a circuit that will perform low voltage DC to AC conversion? Ideally, I would like to have 3 to 6 VDC input (using AA batteries) Approximately 1 VAC output (less would be ...
Paul's user avatar
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1 vote
1 answer
35 views

Low voltage shut off [closed]

I have some temperature controllers that run on 110V. They get 110V from a generator pushing 480 three phase through a transformer to get 110V. The controllers have issues if the voltage drops too low ...
Ron K's user avatar
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4 votes
0 answers
622 views

What is a short-circuit proof cable?

German norms and standards (VDE 250 Teil 602) specify, that wires and cables, rated for 3kV can be considered as "short-circuit proof" and "earth-fault proof" in low-voltage ...
syoma's user avatar
  • 191
2 votes
2 answers
348 views

I need to build a high current, low voltage buck converter

I am trying to power a 14 mΩ resistive load at 0.3 V 21.5 A to add some buffer to the design I'm trying to design for 30 A, since the load can change. Without going too in depth the load is a new ...
user336223's user avatar
0 votes
0 answers
102 views

Why is a spliced USB extension cable frying USB Drives?

I cut a functional USB-A extension cable in half, reconnected the wires, and plugged a USB drive into it. This cable killed three USB Storage Drives. Why? The above photo shows the cable. I know, I ...
Michael Altfield's user avatar
1 vote
1 answer
84 views

Switching low voltage with high accuracy

To do some discharge tests, I want to connect 1.5 V batteries to very low resistances for a short amount (10 - 200 ms) of time, then have them disconnected for at least a couple of seconds. What would ...
JSz's user avatar
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0 votes
2 answers
187 views

LED light data issue

This has been driving me insane for some time now. I can't seem to figure out why my LEDs have issues with communication. They have plenty of power supplied. I broke down my entire circuit to the most ...
astraledm's user avatar
1 vote
1 answer
117 views

Using skin to close low-voltage circuit

I am trying to create a ping pong ball sized light-up ball that should light up when held in my hand, as in the 80's toy inspired by the movie/television series "Star man". The circuit must ...
Erik's user avatar
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0 votes
1 answer
73 views

Low voltage boost-converted versus high voltage on capacitor

Let's say I have a 7.4 V Li-ion battery that I boost-converted to 36 V, and I have a 36 V Li-ion battery. I want to know if a charged capacitor from a boost converter would release energy like a ...
Vely's user avatar
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1 vote
1 answer
82 views

Are there any substitutions for depletion PMOS transistors?

I am currently building a low-voltage cut-off circuit. When the battery is under 10 V, the microcontroller should pull the battery power to ground which will blow the fuse with high current and cut ...
Terry's user avatar
  • 35
0 votes
0 answers
88 views

Low voltage to drive LED flash (not successful in simulation, but works on breadboard)

I first did this circuit on a breadboard, except I originally used a light-sensitive resistor, which is around 1 kΩ at daytime and above 160 kΩ in darkness. It oscillates with LED as capacitor adds up ...
ankyxia06's user avatar
1 vote
3 answers
115 views

7-meter cable between gas meter and microcontroller: too long?

My gas meter has two GND / PULSE pins that trigger a short pulse (probably +3V or +5V) each time 0.010 ㎥ has been used, for use with domotic equipment. There is no power plug in this basement, and I ...
Basj's user avatar
  • 1,906
1 vote
1 answer
72 views

Battery over-discharge protection

I am studying NiMH battery charging and using such a battery on a board to feed other circuits. I would like to add a protection circuit that provides protection for over-discharging the battery at ...
Multicharger's user avatar
-1 votes
1 answer
225 views

Fusing power injected LEDs from both sides [closed]

I am involved on a project where we will be installing thousands of LEDs (WS2812B Addressable strips) on the floor. I have a question about about fusing and if there is a more efficient way to go ...
WirelessTaco's user avatar
2 votes
4 answers
920 views

Low-voltage vacuum tube amplifier design

Amateur radio HF frequency amplifiers using transistors commonly can be powered with around 12 to 14 VDC, or even lower voltages, for QRP transmitters. Tube amplifiers seem to require DC power ...
hotpaw2's user avatar
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1 vote
1 answer
68 views

Thermoelectric EMF problem for low voltage measurement load cell

The resolution of a load cell is highly dependent on its capacity. That's because the higher the resolution and the higher the capacity, the smaller the voltage change. For example, many companies ...
Herza Ryo's user avatar
0 votes
2 answers
133 views

Low voltage connector identification?

Can anyone identify the female and male connectors in the picture? Thanks Here are some more pics Thank you. 1.56mm from pin to pin. So it should be a JST 1.25mm 2 pin micro?
3D Partner's user avatar
11 votes
4 answers
1k views

Powering and dimming a few hundred light bulbs

I want to power a very large light fixture: it has 273 G4 socket light bulbs. The bulbs I found for the thing are 12 V 5 W ones, incandescent. So the question is how to power the beast (as it is 1365 ...
A. Daty's user avatar
  • 113
0 votes
2 answers
363 views

Transistor to switch low voltages (< 1V)

I am building a system for pulsed electrodeposition, where I would like to switch very low voltages (0.3 - 1.0V.) I am not sure about the type of transistor to use for that. A BJT would drop 0.7V, so ...
iblue's user avatar
  • 101
0 votes
0 answers
53 views

potential free output signal with AC as input (no mechanical relay)

Here's what I'm trying to do: I have a a bunch of 24vac actuators running of a 24vac XFR. The actuators themselves are controlled by a thermostat. What I need is a isolated 0v signal when any of them ...
Vulxcn's user avatar
  • 75
1 vote
1 answer
250 views

Replacing button switching 1.3V with microcontroller

First, sorry, I am a total hardware beginner (and 20 years since I had some electronics classes on the uni). I want to replace a mechanical switch (well two switches…) with something driven by a 3.3v ...
Natris's user avatar
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1 vote
1 answer
97 views

How can I select a suitable cable with these characteristics: 690 V, 550 A, 1 km long, AC three phase underwater cable

How can I select a suitable cable with this characteristics: The cable is connected at one end to a 690 V power generator that is between 6 and 40 meter below the surface of a big river and converts ...
Robert Werner's user avatar
0 votes
1 answer
77 views

Two battery control

I have two Li-ion batteries in my system. (7.4 V 12000 mAh and 7.4 V 2200 mAh; also they have BMS). The larger one of the batteries can be easily removed and installed from my system, so I can charge ...
mco's user avatar
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