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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762 views

Low voltage power “distribution” board design

I got a cheap 12 volts power supply (this one specifically) which I want to distribute to several CMOS CCTV cameras (such as this one) which are spread around the house (15m max. distance). Normally ...
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2answers
2k views

Switching a millivolt gas valve with a low-voltage digital timer

I have one of those old gas heaters that has a millivolt valve powered by a thermopile. I want to control it with the brain of a digital programmable outlet timer (minus the AC switching components - ...
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630 views

Brushed Motor Voltage Drop

First of all, I'm fairly new to electronics. I've been working on my own version of a miniature hovercraft just like this one http://www.thingiverse.com/thing:68639. I'm using an arduino pro mini for ...
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1k views

How to reduce 12v to 3.6v

I have led string lights outside (6 sets) that each have their own 3.6v power supply. The power supply's are not weatherproof and are failing. In addition the 6 separate power supply's are not ...
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4answers
444 views

Implement ac-dc converter for low frequency and very low voltage without external powering?

Iam using a basic cascade voltage multiplier to boost and rectify the 0.3v ac signal. The circuit rectifies but the boost is very less. So I thought of using LTC3105 after this stage to get a ...
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2k views

Simple USB powered PIR sensor with LED attached to it (no arduino)

I'm new here and I'm re-new in electronic hence why I'm seeking for some help. Last time I touched a breadboard with a transistor was 10 years ago. So, here's my problem and the problem to the ...
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1answer
89 views

Comparator input below V-

I am searching for a way to use a comparator with possible negative voltage on its inputs. My thoughts and attempts so far: Op amps and comparators with V+, V- and GND: the circuit utilizes a ...
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5answers
2k views

Anything special to consider when running a 12v “Bus” throughout my house?

I've recently begun playing a lot with tiny programmable computers/controllers (like the Raspberry Pi and the Arduino), and I'm planning to distribute several throughout my house as various sensors. ...
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2answers
126 views

Circuit Breakers in Low Voltage Chemistry Projects?

I'm currently using a circuit breaker for low voltage (6V) but high current (60A) electrochemistry projects. My bridge rectifier is rated at 60A max. I'm aware that circuit breakers work in counter ...
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1answer
93 views

Having two variable voltage sources, how drive current only from the larger one at every time?

Suppose I have a circuit I want to power, nominally 6V DC, 500 mA max. The circuit could be modelled as purely resistive (an incandescent bulb, for example). Let Vx and Vy be two different voltage ...
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179 views

LT3663 regulating low

I have a simple LT3663 circuit that I'm using to regulate 15v down to 13.8v. ("24v" is actually 15v in, and "15v" is 13.8v out.) This works almost perfectly. It current limits properly, etc. However, ...
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1answer
736 views

low voltage cut off for 1-cell lithium battery

I am designing a device running on a 1-cell lithium battery. I am really struggling to design the low voltage cut off. This document seems to be a very good solution, but those old parts can't be ...
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5k views

Esp8266 - can I use a 3.7v liion cell without a regulator

I'm more of a hobbyist than a pro so forgive me if I'm asking the wrong questions however I have put some time into finding a solution to this problem. In essence I want to run an ESP8266(esp-12f to ...
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2answers
13k views

TL431 Low battery cut-off

Good morning Could somebody please explain the operation of the attached diagram to me? The circuit was proposed here and here as a low voltage cut-off circuit, which switches off the MOSFET when ...
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3answers
19k views

How fast can a Transistor Switch?

An NPN Transistor can be made a switch by applying some power to the Base. Is there a limit to how fast I can switch the Transistor On and Off? Or I can switch it on and off as fast as i can turn the ...
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1answer
116 views

How can I regulate ultralow voltages?

I'm interested in using a step-up converter that has an input range of 20-500 mV (LTC3108). Is there a simple way for me to regulate the input voltage to less than 500 mV without adding significant ...
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1answer
4k views

Mosfets characteristics suitable for 5V

I want to use a N Mosfet for switching a device from a microcontroller (5V current and 5V signal), and a P Mosfet for giving a signal to the same microcontroller (5V signal , 12V input). (Device ...
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1answer
2k views

Low voltage cutoff circuit with Zener and BJT

I have a circuit that's supposed to cut off at <4V. It instead caps the voltage at 3.3-ish and reduces the voltage linearly below that. Zener - 3.3v Source - 5V +-5V
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4answers
916 views

How To Hold Power ON For Some Time Without Using A Microcontroller or 555?

This is my first question here, so I'm hoping for help. I'd like to take a Momentary event and use it to turn on a device (LED, for starters to model the concept) for a minute (give or take) at a ...
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2answers
3k views

Measuring low voltage AC current with a multimeter

I know that with DC you can measure current by putting your meter in series with the positive supply. I have a project running off a low voltage AC supply. Can I do the same?
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1answer
2k views

How to convert low voltage (< 0.4V) AC to DC

I've made a mini generator for a mini wind turbine. An oscilloscope voltage measurement shows a +0.4/-0.4 V sinusoidal AC current. I'd like to convert it into DC, in order to put a charge and detect ...
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1answer
320 views

Non-diode OR-ing solution for n equivalent power sources

I wish to allow powering my circuit using at least one of 3 connectable periphals. For example, my application could have 3 usb ports that each connect to different usb hosts. Any combination with at ...
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1answer
826 views

Variable vin AC to fixed DC power supply design.. Simplest And Small

Okay, so bare with me on this one please... First post on this stack and still refreshing my memory on electronics in general. So basically i'm working on a project which generates a varying AC ...
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1answer
414 views

Rules on grounding on a PCB with low voltage digital circuit

What are the most important rules for grounding in a PCB? Can anyone explain with reasons? We are making a PCB for electrical power systems in our project. It has high switching converters and some ...
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1answer
100 views

Dual output/dual input canceling 12v trigger

I have a video projector with two 12V trigger outputs (output impedance: 4.7 kilohms). It is attached to two separate motorized screens. Unfortunately the projector software makes the second trigger ...
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2answers
623 views

Simple way to charge 5 x AA via USB - any off-the-shelf component for that?

I need to power a gadget I am building with 5 x AA batteries (6V), but I also want to be able to recharge it via USB (5V) while the gadget is on (that is, I want to be able to plug and unplug the USB ...
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2answers
454 views

Driving a low current solenoid with a low voltage H-Bridge

I'm trying to drive a solenoid to create a magnetic field. I've got a constant current controller circuit that supplies the current I need, but I'd like to control this using an H-Bridge so the the ...
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2answers
192 views

Designing an over voltage protection for really low voltage

I'm working on time lapse photography projects and one of the main problems is the voltage supply. So, using a couple of hot glue tubes I was able to create dummy batteries for my camera to connect an ...
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1answer
1k views

Driving an infrared LED from a coin cell

I am designing a remote-control type IR transmitter that will be powered by a coin cell battery (i.e. CR2032) and commanded by a microcontroller. The LED is pulsed at around 40kHz. How can I ensure ...
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2answers
2k views

PiFace low voltage detector

I'm doing a project with PiFace, but being a software guy my capabilities apparently end when it comes to a circuit to detect low voltage. Basically, as far as I understand PiFace input port is +5V ...
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3answers
8k views

Low battery level circuit - Changing “trigger” level

I am re-creating a simple low-battery level circuit that turns on a low-power LED to indicate that the battery needs to be changed. The circuit is shown below. There are two things I would like to ...
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2answers
541 views

Opening MOSFET's gate with low voltage PWM

I have PWM of very low frequency and very low duty cycle. And max voltage comes out are 3.3. But thats not enough to open the MOSFET's gate(IRFP250N). Now I want to amplify the voltage. I do not have ...
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2k views

Thermocouple Simulation Test Circuit and Voltage Comparator Circuit

I have a challenge that I would like to share with you. (at least a challenge for me) The resistor R8 (10 turn potentiometer) can be adjusted from ~0 to 1K Ohm to output voltages from 3mv to 30mv. ...
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1answer
212 views

ADC Reading is much lower than expected

I am using a EFM32GG990 microprocessor and I am trying to get it to read a voltage using it's on-board ADC. I have made a circuit that I wish it to measure, both the loaded and open circuit voltage ...
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1answer
563 views

Topology for a DC-DC step up converter for a single AA battery with 50V 10mA output

I need to design a very compact step up DC-DC converter for the single AA battery (input voltage 0.7-1-5V) with an output of 50V 10mA. The load should drain in a typical case about 2mA, but in certain ...
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3answers
2k views

How do I keep my constant current source constant?

So I am trying to created a current source that will be used to drain a battery at specific time intervals for a specified duration. simulate this circuit – Schematic created using CircuitLab ...
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3answers
974 views

Need connector suggestions

I have an outdoor electronics project which is running 5V DC through 12 AWG wire to power strands of LEDs through 24 AWG wires. The strands are powered in parallel like so: ...
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1answer
203 views

Best way to provide clock signals for a low input voltage charge pump

I would like to use a charge pump to step up a 1.5V AAA battery to >7V. The charge pump itself is already constructed and works fine when I test it with a 5V input. At this point I'm providing the ...
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2answers
6k views

Battery draining very fast

I have a 48 volts APC UPS (2200va/1980watts) attached to 4 65AH AGM batteries. A week ago after cleaning batteries and terminals, I accidentally put one battery in wrong direction. I turned the UPS on ...
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1answer
2k views

Precision rectifier using a low-power single supply rail to rail op amp

Rectifying a very low voltage signal turns out to be very hard. (for me) I've tried this a few different ways without good results. I'm looking for a reasonable simple solution that performs well ...
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1answer
3k views

Control 12V MOSFET with 5V, with PMW pass-through?

I am new to electronics, and still tying to fully wrap my head around MOSFETs. I have a few questions about controlling a 12v MOSFET using only 5v to the gate, and an incredibly small amount of ...
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1answer
2k views

BJT audio amplifier for 8 ohms 0.025 watts speaker

I have to analyze an amplifier circuit for 8 ohms, 0.025 watts speaker and don't understand how it works. What is the working principle of the components? What configurations are used? In which stage ...
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1answer
3k views

How to calculate Snubber for different load value

We are doing home automation project in that we need snubber for both resistive and inductive load. If we connect less than 5W load(Bulb) it is keep on glowing without switch on. Whether i need to ...
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1answer
139 views

Standards for vehicular lighting connections

I am a cyclist and electronics hobbyist, so I am designing an electrical system for my bicycles. THE QUESTION "What do I need to know (standards, available components, good practices) so that I can ...
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2answers
2k views

How to construct a low input voltage DC-DC converter if no suitable IC is available?

I need to convert a very low input voltage (around 0.5V) to a steady 3.3V output to deliver 50-80mA current with relatively high efficiency (>= 80%). After some research, it appears that some DC-DC ...
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3answers
698 views

1.5V “amplified ear” debugging

I've tried to make this circuit, a 1.5V audio amplifier. I've omitted P1 and directly connected C6 to C3 as stated in the page. I've also omitted the switch SW1 and connected a wire for the path ...
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1answer
161 views

Identifing a connector pair

Male part on the board: Female part in the casing, on the cable. Lockable. What type of connectors are these? Sorry for low quality photos, camera seems to be incapable to do macro job. But male ...
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1answer
226 views

Possible measures to make power supplies safe

I'm looking for a list of ways that mains-powered ELV power supplies with touchable terminals can be made safe in the case of transformer failure with primary and secondary coils becoming connected ...
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2answers
11k views

Mains to low voltage seperation between FR4 PCB layers

I cannot find clear information on running mains and low voltage on adjacent layers on FR4 PCBs. I understand how much creepage distance to allow, but for example, can I run - 50Vdc, 240Vac, 0Vac, ...
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2answers
286 views

VDC for little centrifugal pump. How much tolerance?

Can I run a little 7 VDC (1.2 watts) pump with a 9 VDC/0.5 Amp power supply? (The pump is for a drip to attract birds.)