A voltage regulator is an analog circuit that produces a stable output voltage that doesn't vary with input voltage or load changes. Switching regulators are much more efficient than linear ones.

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Portable phone/device charger

I am doing my best to make a portable charger. Here is the link with the schematic of the circuit I am working on:Voltage regulator question .I was told that the 9 V battery I was using didn't have ...
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2answers
40 views

Feedback op-amp voltage regulator help

I have made a voltage regulator: simulate this circuit – Schematic created using CircuitLab And here is the zener circuit: simulate this circuit I have already tried to charge ...
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1answer
30 views

arduino boot up button and shutdown mode on regulator

We've a projet with an important autonomy concern. We use an homemade arduino (atmega328), and for the moment we're using interrupts on buttons to wake up the atmega. so we have: sleep ->(button ...
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0answers
45 views

SLA (Sealed Lead Acid) Battery Float/Trickle Charger Design

I would like to replace an unregulated transformer-based built-in charger in an emergency LED lamp. The biggest problem with the original charger is that when the current tapers off, the voltage ...
0
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1answer
49 views

need advice with LM317T current limiting circuit ,new alternative

i am using an LM317 as a Current Regulator for series LED similar to protecting LEDs From over current ( in time of short circuiting) for my LEDs and Mosfets, similar to this picture: the problem ...
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0answers
44 views

LM2596 voltage dropping

I bought a cheap LM2596 adjustable buck module from eBay and I connected it to 19V power supply and adjusted it to 5V output. The problem is that when I add load the voltage drops, which is not what ...
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7answers
1k views

Transform 8~13V to 12V

I'm trying to build a diving flashlight and now I'm stuck with the electrical part. I have a \$12\$V \$10\$W high brightness LED, and am now trying to decide which is the best option for the ...
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2answers
39 views

Current consumption by a LDO (5v to 3.3v)

There is a LDO that converts 5v to 3.3v and has a quiescent current of 0.11mA. Suppose it powers a ultra low power digital sensor (i2c or spi based) that uses only 50uA, (there is an mcu too but that ...
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0answers
38 views

LT8609 DC/DC stepdown not working correctly

I am using this exact circuit with the exception of a 2.7uH coil (closest available at the local parts store). It is an example provided in the LT8609 datasheet: The only load is an LED with a ...
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1answer
56 views

how to design a rheostat which gives me fix 24V supply for different input of 24V,48V,110V,220V [closed]

i want a constant voltage output using rheostat. It can be any electronic circuit control or by appropriate tapping.
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0answers
52 views

Why is the output of my 5V step-up voltage regulator the same as the input?

I'm trying to step-up voltage from a solar cell. Using a lamp, the cell outputs a constant 3.8V. The output I'm getting from the voltage regulator is about 1.5V. Why is this? I have a 1000uF capacitor ...
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4answers
826 views

Two voltage regulators in series vs in parallel

What is a better idea - to connect two voltage regulators in series or in parallel? I don't need much current (max 300-400mA). I need both voltages. Transformer output is about 9V. U2 gives 1A max and ...
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1answer
76 views

Can the LD1117V33 handle short peaks of up to 900mA?

Got a project with the typical 5V and 3.3V power requirements. My initial prototype I used the LM3940 (datasheet). This worked pretty well but these regulators are damned expensive here in Australia ...
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2answers
65 views

Arduino digital input - Read voltage slightly higher then 5V - a power efficient solution [duplicate]

I need my Arduino to detect the state changes in a device - (ON or OFF). In order do do this, I have to check the voltage between two points on the PCB of the device. When the device is OFF, the ...
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1answer
45 views

Can decoupling capacitors be doubled up? Xbee + VR both have them

I'm using an MCP1700 low-dropout voltage regulator to power an XBee separately from my other Arduino circuit, because it can use up to 215mA all on its own. There are 1uF decoupling caps on both the ...
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2answers
108 views

How to achieve the max efficiency from a Buck converter

I have a question about switching step-down regulators. (As I stated in my previous questions, please consider the fact that that I'm not very expert, so feel free to reply/talk as if I were a ...
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3answers
88 views

Voltage Regulators Transistors?

I am new to electronics and I was wondering, how can I distinguish a transistor from a voltage regulator and the opposite? For example here are 2 images, 1 of a transistor and 1 of a voltage ...
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2answers
43 views

Low cost, wide bandwidth voltage reference

I have designed a circuit with 5V single-supply op amps, but since the inputs to the circuit are AC, I need a biasing voltage to replace the ground node on the equivalent dual supply circuit. Without ...
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0answers
97 views

How to run a 5V device from 40V

I am working on a power supply circuit that has 0 and 40V rails. It contains a single op amp that has inputs in the 20V range. While digging through my op amp stash, I realized I only have tiny 5.5V ...
2
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1answer
76 views

Using 2 7800 series regulators to get -ve, GND and +ve voltage rails

I was wondering if there is a way to use 2 linear regulators in series to get positive, GND and negative rails. For example could you connect 7805s to get outputs like drawn? This is more of a thought ...
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1answer
65 views

Most efficient way to drive a low power LED at half brightness

I'm working on a small project where efficiency is very important (every mA counts). I need to drive two red 3528 LED's in series and only have a 9V DC source. I want the LED's to be only around half ...
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0answers
45 views

Guarantee 9V operation with a battery or wall powered device

I have a device I want to provide a constant 9V of voltage to it while both using a 9V battery or while it has 9V DC power supply running into it (with or without battery) whilst seamlessly ...
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1answer
57 views

Step Down Regulator - Output voltage unstable/voltage drop with load

I'm currently trying to build a USB charger device for my mobile phone using an old 12V car battery as power source. I purchased different step down modules (see below) to regulate the voltage from ...
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2answers
74 views

Powering a device through GPIO

I have a custom PCB based on imx28 (primary board). It receives external power via a cable. There is another PCB (secondary board) connected via GPIO to the primary board. The secondary board doesn't ...
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2answers
87 views

In an op-amp, what does connecting the negative supply to the feedback do?

I'm trying to understand how the LM317 works? I've found that a good simplification is the following: So a practical example would be simulate this circuit – Schematic created using ...
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2answers
65 views

Variac is blowing fuses

I'm using a variac to control voltage on a heating element and we're having issues with the fuse blowing. The variac is rated for a 10 amp fuse and we're using a 8 amp one. The 8 was suggested to ...
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2answers
68 views

Controlling Voltage

I'm seeking help in finding a way to control the incoming voltage for custom LED fixtures. My fixtures use 12V 3014 240/M LED strips with 221 resistors. The strips are wired in a parallel circuit ...
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1answer
65 views

i want to make circuit to drop voltage 24v input to 10v output by using resister [closed]

i want to make circuit to drop voltage 24v input to 10v output by using resister By the help of pot meter.
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2answers
71 views

How to change speed of dc motor using potentiometer?

I want to change the speed of a DC motor(12V,2000RPM) using a pot and operate a table fan(where I've replaced its AC motor with DC).Now the problem is I get a regulated output at o/p of 7812 but not ...
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1answer
69 views

12V regulator for 100W LED

I want to make a 100W high power LED headlight for bike, but the problem is that LED releases a lot of heat, and I'm using a 150W boost converter to convert 12V to 30V ( minimum operating voltage of ...
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1answer
40 views

Need help finding a replacement regulator [closed]

Im trying to find a replacement for the low dropout voltage regulator shown in the pic, im located in the U.S.(Florida). All help appreciated.
2
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1answer
55 views

Better to regulate voltage by supplying or subtracting base current to BJT pass transistor?

As a learning exercise, I'm designing new guts for one of my venerable HP 721A (circa 1959) DC bench power supplies. With help from members of this site I was able to vastly improve the reference ...
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2answers
41 views

Voltage regulator current consmption

Our pcb current consumption is less than 0.5mA . We use a 3.7v lithium battery, and the battery goes through voltage regulator ...
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1answer
55 views

3.3V Voltage Regulator for LiPol battery [closed]

I'm looking for a low drop voltage regulator to use in a 600mA – 1000mA (peak) 3.3v system that can be powered either through a singe-cell LiPol battery or USB (so a max drop of ~0.4V). So far the ...
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2answers
53 views

would using the reference voltage of an ADC as a VOLTAGE SOURCE affect my ADC or the stability of the circuit?

I am using an Arduino to capture an AC signal. However, the application is sensitive and needs a high resolution, I decided to use the internal 1.1 Volt as a voltage reference for the ADC. In the ...
2
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2answers
577 views

Will the lower frequency of 50Hz AC affect overall charging time? [closed]

I'm using a voltage converter to go from 220V to 110V to charge a small appliance. The recommended charging time is 6-8 hours. However, this is specified for US AC voltage 110V@60Hz, whereas the ...
0
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1answer
27 views

LT3029 regulator for arduino mega

Does the LT3029 regulator give out 9v 500mA without external circuitry needed for it?... I'm planning to use it for my arduino mega... I really haven't used that regulator before ...My main power ...
0
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1answer
55 views

Reduce voltage after AC-DC rectification before step-down

I have a Weller Magnstat soldering station providing 24V AC to the tip. I want to use that output to power a 12V fan to disperse or absorb the fumes. With a cheap multimeter I measured 25V AC during ...
4
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5answers
920 views

Is there any advantage to biasing a transistor with a zener diode rather than a (resistor-based) voltage divider?

In the figures below, we see two methods of biasing a bipolar transistor: the first uses a voltage divider, and the second employs a zener diode regulator. Since the voltage regulator appears far ...
0
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2answers
63 views

Will AVR stabilize the flow of current? [closed]

In our village, the power supply is unstable. Sometimes it goes weak, sometimes not. You can tell it by our bulbs, it goes dimmer when the power is weak. Our monitor now shows some green and red wires ...
0
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1answer
36 views

TSP65070 and OMAP 1V8 pull up to 2.7V

I want to use the TPS65070, the power solution for DSP to power the OMAP L138, but i read in the errata sheet of the OMAP L138 OMAP L138 Errata page 25 that the 1V8 power supply can pull up to 2.7V ...
0
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1answer
27 views

Can I use an electrolytic capacitor with a MCP1826S voltage regulator?

I have a MCP1826S and according to the datasheet, I should use an output capacitor of 1-10uF and with an ESR of lower than 1Ω. I have some 4.7uF electrolytic capacitors, but I think they have an ESR ...
0
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0answers
40 views

reducing voltage for an external battery pack.

I'm trying to build an external battery pack for a cannon camcorder from NIMH rechargeable D cells. I need to reduce voltage by 1.07 and keep constant voltage. I'm connecting through the charging ...
4
votes
2answers
96 views

Increase LDO current with PNP

I have seen this circuit a few times. It takes a common 3 pin LDO, and adds a PNP transistor between VIN and VOUT, to increase the amount of current it can provide at the regulated voltage. It is ...
1
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3answers
82 views

Help with understanding strange capacitor configuration arrangement

I am on a chapter of my electronics beginner’s book where the author talks about the PICAXE microcontroller. One of the first things the author mentions in this chapter is to make sure that the PICAXE ...
0
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1answer
110 views

Design an E-switch

I'm trying to run a OLED display densitron with a ssd1322 controller. It requires basically two supply voltages 15V VCC supply and maximum 3.5V Vci supply voltage for operation and IO pins. There is a ...
0
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1answer
52 views

Connecting the voltage sense screws of a power supply (wire gauge to use?)

Very often I see high wire gauges (i.e., very thin cables) used for the wires that connect a test circuit's voltage input terminals to the sense screws of a power supply. I would have thought that you ...
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1answer
74 views

Negative supply from LM3940

I got a bunch of LM3940 to convert 5V to 3.3V. I wanted to use the same to make -3.3 V so I switched the ground and output. In the schematic the top circuit works fine and I get 3.3V out. I expect ...
0
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3answers
206 views

Any clever way to provide 3.3V with good current output from a 9V battery?

I'm sorry for any English mistakes as I'm not used with using it when talking about technical stuff. I have been using some ESP8266 WiFi modules with Arduino Mega for a project. They work with 3.3V ...
0
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1answer
66 views

Should I use a regulator to improve efficiency or safety

I am considering a low power design where I do not use a regulator. The components will operate from 1.9 to 3.7 Volts. The design is powered from two primary cells(Nominal Voltage: 1.5 Volts ...