Questions tagged [low-voltage]

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

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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 ...
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0 answers
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What sort of testing goes into satisfying the CE Low Voltage Directive?

I am designing a product that uses a third party 120/240 volt power supply that has been CE and FCC rated by its manufacturer. The rest of my system is operating at 12 volts DC. I will have some hand ...
1 vote
1 answer
38 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 ...
0 votes
2 answers
71 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?
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 ...
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0 votes
2 answers
116 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 ...
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41 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 ...
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0 votes
1 answer
88 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 ...
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1 vote
1 answer
84 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 ...
0 votes
1 answer
59 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 ...
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0 answers
101 views

High Voltage & Low Voltage PCB Design

I am trying to make a PCB that acts as a "Raspberry PI HAT" and allows me to connect the raspberry to different sensors. Specifically, I'm having difficulties in defining the design rules ...
10 votes
3 answers
2k views

Is it okay to charge a deeply discharged Li ion cell below 1V?

I accidentally discharge my lithium cell to 0.45V. Is is okay if I try to revive it by charging with 10mA of current till it reaches 2.5V? cell capacity is 4000mAh.
1 vote
1 answer
239 views

Blocking oscillator, Slayer exciter drawing too much power

I am trying to build one of these using an air-core coil. I got it oscillating but have to cut power off after 4 seconds as it starts to heat up (can't hold it with my fingers.) The transistor is not ...
-3 votes
1 answer
91 views

12V-only (and no 110V/220V) household electrical installation [closed]

Power outlets are in 220V/110V in houses for historical reasons (light bulbs and other appliances probably required >100V voltage) but nowadays as: we use a USB charger 220V->5V for phones, ...
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1 answer
46 views

Single vs two pole breakers - Single phase loads on IT power with distributed neutral

Are two-pole breakers required on single-phase 230 V loads when connected to a 3-phase supply with IT earthing system (with distributed neutral) in Germany? Where in the standards is this requirement ...
1 vote
1 answer
174 views

3 phase low voltage signal generator

I want to create my own 3 phase signal. However, instead of it peaking at 230V AC it must peak at 5V AC. This generator will be used to feed a secondary unit that uses this signal to perform its own ...
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0 votes
1 answer
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Low voltage asymmetric duty cycle oscillator

I'm designing a low voltage (1.6 V and less) LED decoration. The source voltage is a low power, high impedance energy harvesting source. With the following characteristics: deliver between 0.8 and 3 V ...
1 vote
3 answers
138 views

Can I use a 1kV capacitor for a 5V circuit?

In a different question, it was asked if you could use a relatively higher voltage cap in a 5V circuit (35V cap). It seems that's ok, but I want to know if that logic is still applicable towards the ...
2 votes
2 answers
74 views

Regenerative Drive VFD when drive is a major % of network load?

I'm in the process of designing a new facility with about 50-60 VFDs in the 5-10 HP range, another 5 VFDs in the 100-225 HP range, and then one burly beast at 1000 HP. I've been looking into various ...
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0 votes
3 answers
101 views

Why do we not see multiple or parallel DC PSUs?

A friend mentioned that his home router had blown its 12V PSU recently and had to be replaced. That got me wondering - Servers and routers can have isolated dual PSUs for exactly this condition, but ...
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0 votes
1 answer
68 views

Design a flashing circuit that uses PWM signal and MCU signal to control when it is on and off

My team and I are working on the low voltage systems of a solar car and have an issue with figuring out how to flash the turn signals on the car. The options we are exploring include: Using a 555 ...
0 votes
2 answers
168 views

Help with constant current load hysteresis

The circuit above is a constant current load based on an LM358 comparator. It is very useful to measure the capacity of lithium-ion batteries. The original circuit I found online had a 5V supply but ...
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1 answer
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Low-Voltage Unidirectional Ground-Level Shifter

Greetings, electronics Mavens! I'm trying to interface the status LEDs of a third-party device to the GPIO of my ESP32. I am using internal pull-ups on the ESP32 inputs, and trying to trigger on the ...
-1 votes
2 answers
273 views

What will happen if I use RCBO where there is no neutral in the system?

I need some help. Could you please go through the scenario and try to answer my query below? This system is installed in a ship where there is no neutral connection available. A 440V/220V step-down ...
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2 votes
0 answers
67 views

Isolating low-current, low-voltage digital signals

I'm working with a battery-powered sensor that allows reading its measurements using two digital signals - a clock and a data line. The clock speed is abount 3kHz. In addition to those two signals, ...
0 votes
1 answer
344 views

Low voltage MOSFET gate drive

What is the best way to drive a MOSFET with low voltage? I have encountered several projects where power from a battery is used to drive motors or source a DC/DC converter. In most cases, we used an ...
1 vote
1 answer
729 views

Can I use a multimeter to verify if RX/TX of a device is working?

To summarize a problem: My electricity meter uses a HAN interface (via M-bus) to transmit the meter's data every 10 seconds. Apparently this HAN interface can be enabled/disabled by my energy provider....
2 votes
1 answer
52 views

How to wire two open-drain logic outputs to a three pin bi-color LED

I am very new to working with electronics; my main experience is in programming. I am working on a project and intend to use this MCP73833/4 Li-Ion Charger. It has two "Charge Status Output" ...
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1 vote
1 answer
199 views

How to block low voltages in a very low current circuit

I have a circuit circuit fed by a 48V nominal lithium battery source. I'm using a few simple resistors to divide the voltage down to a suitable range to drive a p-channel mosfet gate. When the battery ...
1 vote
1 answer
161 views

How can I block low voltage?

I have added a picture about my circuit. Please look at the picture. How can I safely provide the logic in the image? What kind of circuit should be in low voltage control block? I have to cut off Vo1 ...
1 vote
0 answers
693 views

Update very old, very low voltage (10V) Nutone doorbell system to new 16V chime

I have a Ring video doorbell that is connected and functioning to the old doorbell wires, which I measured at 16V. I also have a old Nutone Scoville 10 V, 5 VA transformer tucked in a very hard to ...
0 votes
2 answers
72 views

Safety with low voltage high current safety

For my work, I’m working on a project that uses a power supply that outputs 42A DC at 5V limit. While I know that 5V is nothing if I were to come into contact, poor grounding can still cause flashes ...
-1 votes
2 answers
110 views

Can I power a 35 Watt light fixture over a thermostat 5-wire?

I would like to add this light fixture to my ceiling in an area that only has a thermostat 5-wire coming out (something like this). (The other end of the thermostat wire travels about 15 feet, ending ...
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0 votes
1 answer
104 views

Can an Adjustable Circuit Breaker be adjusted while Energized?

For a Low Voltage Circuit Breaker, such as the Legrand DPX3 630, 3x400A, 36kA, 400V, we have adjustment dials to change the properties of the magnetic (Magnetic adjustable from 5 to 10 In) and or ...
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1 vote
1 answer
352 views

DC-DC boost converters in parallel to run DC motor

Our aim was to power the motors of our bot (which were selected according to the torque requirement of our bot) using a single AAA Battery but due to limited time and and the difficulties in ...
0 votes
0 answers
103 views

Relay: wetting contacts before using sub-wetting current

I'm considering using small signal relay for my application since I need to switch shunt resistors to measure currents from 1uA to 10mA (two shunts) with voltages from 0V to 5V. Now, it's clear for me ...
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0 votes
1 answer
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Modifying the MT3608 DC-DC Boost convertor

I am using the DC-DC boost converter MT3608 for a project where my input ranges around 1 V. Is there a way to modify the circuit so that the boost converter can operate at voltages less than its ...
0 votes
1 answer
88 views

How to protect low-voltage hardwired device against 120 V AC miswiring ? (I need a resettable solution)

I need to protect a hardwired device, made for AC low-voltage transformers (e.g. doorbell), from miswiring to a 120 V AC power line. It actually occurs no matter how many warnings I put everywhere. ...
0 votes
0 answers
27 views

Low voltage beak away/tension release connectors for building to building overhead cables

Are there low voltage breakway or tesion release connectors that should be used for overhead, building to building applications? The background is we are running a single pair of speaker cable, and a ...
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2 answers
147 views

Low voltage directive

I just want to check my understanding of LVD. I have a portable device that operates on a 30V DC input. Its output is less than 30V DC and is powered by a wall plug (UK 240V) that I supply. Am I ...
1 vote
1 answer
83 views

low voltage radio frequency amplifier [closed]

Is it possible to build an RF transmitter final amplifier that can be powered by a single lemon as a battery? (maybe 0.9 Vdc at 1 mA, with suitable electrodes, when fresh) Desired operating frequency ...
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0 votes
2 answers
249 views

Voltage Limitations of a header being used as a voltage selector

I have an application that takes a reference voltage. These voltages could be considered 'low voltage' as they range from 0 to 1000 V. Below is a reference schematic of what I'm trying to accomplish, ...
0 votes
1 answer
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How can I electrically isolate two 24 VAC sprinkler controllers working on the same output (master valve)?

I have an old 24-zone sprinkler controller and I'm trying to move 16 zones to a "smart" sprinkler controller. I have a master valve that has to be switched on to provide water downstream to ...
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1 answer
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how to calculate hysteresis resistor value TL431

I'm creating a small ESP32 based robot controller board. Partially as a self learning experience (mech engineer, self taught on eletrical front but this is for hobby use :P) and partially because it ...
0 votes
2 answers
303 views

back gate effect in low volatge circuits

1- In some circuits (Low voltage ones) the body of the pmos is connected to the gnd and nmos to the vdd. i wanted to know the reason behind this technique or in others words what's the idea behind ...
6 votes
2 answers
130 views

270a DC inrush, 130a DC nominal load. 14 vdc supply. Ways to limit circuit to no more than 11.5 vdc?

What device can be installed between the glow plug relay and the power leads to the glow plugs, to allow ANY voltage under 11.5 vdc, but allow no more than 11.5 vdc, regardless of how much higher the ...
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Nodal voltage magnitude properties of electricity distribution networks

I am wondering how to know about an electric bus according to its measured voltage magnitudes (possibly and its corresponding real power injection profile). Following assumptions can be made: One ...
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4 votes
2 answers
664 views

Solution for how to drive a P-Channel MOSFET when Gate/Source voltage is too low?

I have used this forum to lookup solutions and suggestions from time to time but this is my first ever post! There are many great P and N-Channel MOSFET Questions and Answers in here, but I cannot ...
1 vote
2 answers
113 views

Is upsized reactor allowed for the comparitively less motor HP?

We have a LV-MCC in our commercial outlet having a 480 VAC, 15 HP VFD with line and load reactors in series with it. The VFD is sized for 22.0 A (normal duty), the motor has a horsepower rating of 10 ...
2 votes
0 answers
278 views

Controlling 120v line with a 12v switch on a different line

I have 10a 120v power sockets in my garage that currently doesn't have any switch on it and powers some overhead lights that I have plugged in. Separate to that, I have a 12v circuit powering various ...
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