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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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24 views

Digital voltage stabilizer relay diagram

I am using this voltage stabilizer relay diagram below, which provides a 16 step-up level. I need to edit it, so that I can made it to work as step-down in case of high voltages such as 245 and above. ...
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80 views

Stabilize circuit on 5V 2A

I have not yet build following circuit: Circuit in high performance needs 5V 1.7A (measured). I have source which is powerbank with 16 000 mAh. Outputting via ports: USB-C 5V/3A, USB-A 5V/3A, Micro-...
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3answers
75 views

Does the Rds(on) of a MOSFET vary based on source-drain voltage?

The Rds(on) of a MOSFET decreases when you apply higher gate voltage, but does it typically vary based on the source-drain voltage? I will be using a MOSFET to switch very low voltages (10's to 1000'...
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51 views

Electric heating for glass melting furnace

Some furnaces use electricity for glass melting. Low voltage and high amperage power is passed through the molten glass through 2 molybednum electrodes dipped into the glass. The molten glass acts as ...
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1answer
46 views

How to determine which harmonized standards are relevant to achieve CE conformity declaration

We are aiming to develop our first product to achieve a CE marking. So far i understand that there are a few directives like Low Voltage Directive (LVD), ROHS, EMC, etc, which can be implemented by ...
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4answers
142 views

Too High Voltage Drop across Transformer's Output

I want to get very high current flow thought secondary winding of transformer on my 3 Ohm load. As I apply high voltage of secondary to the load the voltage across it drops dramatically. Only about 2% ...
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1answer
52 views

Reducing the start-up voltage of a low voltage cut-off circuit

I just built this circuit, with the intent to use it as a low-voltage cut-off switch for a single li-ion cell. It works great, but once it's triggered it needs about 7 volts to turn back on, so I ...
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2answers
31 views

Pros and cons of centralised vs decentralised power deliver for small devices

How does compare using one power supply for multiple devices vs each device having its own - regarding efficiency eg. power consumption? Model situation: Home automation using low power devices such ...
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1answer
71 views

How to convert high voltage DC at low amps to low voltage DC or AC at high amps?

How to convert high voltage 500 volts DC at very low amps to lower voltage 12 volt DC or AC at high amps? Must I use an electrostatic motor or can I use an op amp? The reason I am posing this is a ...
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2answers
94 views

Cheap Low Power Signal Transmission To Smartphone

For my university project I'm making a certain sensor which has to (one-way) communicate with a smartphone. The sensor needs to be as cheap/simple as possible (aiming at +- €0,50 in total) and only ...
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2answers
183 views

3.3V overvoltage limiter circuit topology

I need to design, using discrete components only, a shunt voltage limiter that drains little or no current (less than 2mA, the lower is better) at 3.3V, and ensure that, when driven at more than 4V, ...
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24 views

BLDC generator mode low speed boost voltage

for my final year project i might use in hub wheel motor (bldc), now the bldc on low rpm produce low voltage. is there a way i can increase voltage (boost) like a normal dc motor ?
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4answers
85 views

Can I provide a constant charge to a battery?

I have a sketch here of what seems like a solid plan. sketch I need to provide a .2ohm coil around 3.7v which will take around 20 amps. The load will be very brief; 3-5 seconds, and intermittent; ...
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0answers
133 views

Low voltage cutoff circuit with PV panel

I'm trying to build a simple reliable low voltage cutoff circuit and sufficient voltage turn on circuit for a PV panel powered circuit. The idea was to supply power from PV panel to a working circuit ...
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1answer
60 views

Safety for 48v leds in water

I'm builing a 48v DC LED system to be used inside a fountain in a public space. I'm using a 48DC 30A switching power supply. What should I do to make it safe in case any conductor gets exposed to the ...
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2answers
251 views

Determining safe current and fuse rating for LV LED lighting

My home builder pre-pulled a length of 18-8 solid copper wire (18 AWG, 8 insulated conductors inside single jacket) into the ceiling of a room where I want to use some LED lighting with a remote power ...
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1k views

Smallest circuit for Ultrasonic Mist Maker or humidifier

I am working on Ultrasonic Mist Maker or humidifier circuit, but does not found any good circuit. As search on google that we have to make about frequency 1.6MHz to convert water into mist. using ...
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1answer
84 views

Safety Standards for Low Voltage Systems

I am looking for safety standards which could be applied to the piece of equipment desribed below. Basically the piece of equipment is a housing which inherits a 24V 100Wh Battery (2x SBS60) and a ...
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2answers
75 views

Logic level for system lower than IC's recommended logic level

My system has a logic-level and logic-supply-voltage of 2.4V. I want to use a particular IC in it (which basically operates as a shift register), and the datasheet says the minimum recommended logic ...
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1answer
215 views

Multiplexer for low-voltage measurements

How does voltage leakage (or cross-talk) from a mux affect low-voltage (voltages on the range of 10s of microVs to mVs) measurements? I am building a measurement set-up consisting of a Keithley 2400 ...
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3answers
138 views

Detect voltage below 0.7V? [closed]

I have a LED in circuit which I want a circuit to detect whether it's on or not. I have found ground and +ve of the circuit. And I checked the voltage across +ve of LED and Ground, when it is ON, it ...
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1answer
80 views

What DC motor controller will work for a small toy train? [closed]

I'm thinking about modifying a battery-powered toy train to use a higher voltage battery so the toy can go faster. Like this: https://youtu.be/qK-IVIllOBY?t=30 The 9V battery has a nice form factor ...
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1answer
566 views

PIR (HC SR-501) not working

I'm working with ESP8266 Wemos D1 Mini and HC SR-501 (PIR sensor) in one particular project (please, see the circuit image in annex). The question is the HC SR-501 stay always LOW. I tried change the ...
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0answers
64 views

Specifying & operating a TRIAC with a low voltage load

I am looking to do a circuit to switch a 12 VAC of a device to the ground. I intend to use a microcontroller to drive the TRIAC. The goal here is only to short the 12 VAC of a device to its ground. ...
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2answers
99 views

PCB relays for switching 700-1000V analog signal [closed]

I'd like to switch the polarity of a differential high voltage line that carries up to a 750V (+/-375V per conductor) analog signal. The easiest way to do this appears to be to use a dual-pole dual-...
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2answers
392 views

Low voltage disconnect with no quiescent current

I'm a noob. Please correct my mistakes. I'm making a circuit where I'd like to protect my Li-ion battery (3.7V, 3500mAh) from discharging too much. The batteries have a protection inbuilt which shuts ...
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2answers
138 views

Calculating resistance when ohm law has no response

I have a 3v DC source and a 3v light emitted diode, i want power this led with just 5 mA . There is a formula : R = V/I But in my case V is 0 V[source] - V[LED] = 0 So R is 0 always!!! How can i ...
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3answers
3k views

Circuit with 10 LEDs with 9V battery

I know that a 9V battery can only power so many LEDs. I need a 9V battery to power 10 of them maybe less or a few more and keep brightness and im not sure where to go to make it happen. Or if i ...
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1answer
78 views

How to convert 0.08 V of AC to DC

I am using an insulated wire as an antenna, which is picking up 0.08 V of AC. I want to convert that to DC. I know I need to use a rectifier, however my configuration doesn't seem to be working. I ...
2
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1answer
126 views

Switch off this single cell lithium hi-power LED driver with protection circuit

I've been goofing around the internet trying to build my own flash light with a single 18650, with low voltage protection circuit. For now this circuit can already achieve following ideas: Standby ...
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3answers
236 views

Isolated way to detect 240V contact closing

I want to create a small project with an ESP8266 that makes a server call when a thermostat is open or closed. My main problem is detecting the thermostat status. The electro-mechanical thermostat ...
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0answers
57 views

Unknown 2-pin weatherproof connector

We have a meteorological station (Made by the now-defunct Solar Millennium) next to our solar plant that has a faulty connector from its PV panel. It has a circular cross section and has a screw-in ...
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1answer
184 views

Using flyback diode with relay, load regulation faults occur

I'm having a problem with load regulation errors on my board. When I engage our load with a relay, it causes a metering chip in our system to reset. I've placed a picture of the relay with the flyback ...
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4answers
701 views

Low voltage cutoff circuit not working

I've spent the past 10 hours trying to figure out why my low voltage cutoff circuit won't work, and I'm at the point where I feel like I need to ask for help. The idea is to slap this circuit in ...
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2answers
2k views

Can I run a 12v fan off of a 9v power supply for LED lights and are there any side effects

I have multiple (9v 1500mA to 9v 3500mA) LED light fixtures that I have tested chaining a single fan (12v 5.2w and 12v 0.16A fans) and they seem to work under the brief test with enough air flow for ...
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4answers
2k views

AC vs. DC in Low Speed, High Torque application

My club is building a 1/4 scale utility tractor (around 800 lbs) and for the past couple of years we have been using an electric hybrid drivetrain. Our system has been a 32 hp gas motor powering a DC ...
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2answers
169 views

Biased single-source relaxation oscillator not starting

Vcc is 5 V , first op-amp LM358 provides 2.5 V ground for easiest possible relaxation oscillator build with MCP661 (2.5/5.5 V supply, 60 MHz operational range). I wanted to use it to measure values of ...
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2answers
1k views

Do low voltage “Nixie tubes” exist?

I want to make a small clock using Nixie tubes (for the cool/retro/steampunk look of them), I have some basic knowledge of electronics, but I have never done anything with more than 12V DC and ~10A. I ...
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1answer
90 views

Low Voltage AC to Dual DC supply

I have a special power supply requirement for Agro Based Applications.. After stepping down conventional primary 230VAC, 50Hz Single phase single line supply to secondary 80VAC (4Amps to 6Amps), I ...
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1answer
131 views

Measurement of highly resistive samples with Keithley 2182a nanovoltmeter

In our laboratory we are measuring transport properties of various materials. Currently we have deployed Keithley 2182a nanovoltmeter. When measuring bulk mineral (tetrahedrites, Cu12Sb4S13 Peru) ...
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1answer
57 views

LED Power Box Design

I am designing an LED power supply unit, using off-the-shelf constant current drivers (Phillips Xitanium). The system will include a 0-10v dimmer, and I need to connect the Xitanium to both 120v for ...
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3answers
1k views

Can I make a VCO full audio range with only one capacitor?

I'm trying to make a VCO with a low voltage setup (3.3V), and i 'm using a mcp6002 op-amp. I'm controlling the frequency with an MCP4822 (dac). The problem is that i get a limited range of frequencies....
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4answers
169 views

How to indicate Low voltage(2.7kV) and normal voltage(above 2.7kV) in 3.3kV 10uA power supply through LEDs

I have a power supply which gives 3.3kV 10uA output. Now what i need to do is to turn ON a Green LED when the voltage is above 2.7kv and turn red LED ON when it goes below 2.7kV. Could anyone guide me ...
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2answers
244 views

5 mA low dropout voltage, current source [closed]

I want to power two signal LEDs in series, about 3 V in total from a 3.3 V supply. The on current is 5 mA and I can switch either the positive or negative rail. Using only a resistor will not be ...
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3answers
5k views

How can low voltage, high current (kA) power be dangerous?

Aluminum refineries use electricity to separate aluminum from minerals it naturally occurs in. This electricity typically takes the form of low voltage DC ("low" meaning 4 to 6 volts), at very high ...
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1answer
396 views

Braiding 3 Phase Wires

I'm working in the 50V, 10A range with un-shielded wire to drive a brushless DC motor. Are there any advantages to braiding the 3 phase wires? will it reduce EMI and spiking?
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1answer
826 views

L298N (via 74HC595) motor control - unexpected voltage & motor not spinning

(Corrected version as last text was somehow corrupted) I have made a circuit with L298N in order to control direction of 2 DC motors. When I power the circuit I noticed that voltage between 2 output ...
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4answers
222 views

Filter-Amplifier circuit for Low Voltage I/P circuitry

I'm designing my first ever circuit for a hobby project. I've a sensor that outputs in mV (1 to 2) and a controller with ADC. The ADC is 16 bits, VDDA = 3.0 V, Temp = 25 °C, fADCK = 1.0 MHz. Since the ...
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1answer
36 views

Powering an SN754410E from Arduino logic pins

I want to run a very small stepper motor using a 5V source (specifically, a stepped-up Lipo battery). Since both the stepper I have and the SN754410E are rated to operate from 5V up, I figured this ...
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1answer
2k views

Using a relay to turn on and off really low voltage circuit

I want to build a thermostat for my fireplace. I want to use my Arduino to turn it ON and OFF. The fireplace has got a switcher on the wall and I have measured it and the voltage different from one ...