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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Can I use an op-amp in voltage follower configuration as variable voltage power supply?

I see that this works in theory, but I my gut feeling says there is a drawback or caveat of which I'm not aware. Basically what I want to achieve is described best by the circuit diagram below. ...
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56 views

Taking an unstable DC voltage, and stabilizing it

I have a DC motor generator (basically the motor spins, and it powers an LED at the moment), and the output current (mAh) and voltage (V) is very unstable. The goal is for the entire circuit to run ...
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99 views

can a voltage regulator circuit be modified to put out PWM?

can a voltage regulator circuit be modified to put out PWM? i'm putting a full-wave rectifier circuit and voltage regulator circuit on a pcb. i'd like to modify the vreg circuit so that it puts out ...
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1answer
39 views

Can I dynamically change STM32 voltage during runtime

I'm using an STM32L151 MCU for a battery powered wireless sensor node. I came across the TPS6274x series switching regulator, who's voltage can be reconfigured at runtime by flipping it's inputs. The ...
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32 views

low dropout regulator output voltage

I want to use the DMOS low-Dropout regulator REG102 3V3, but in the datahseet REG102 of the regulator i found two configuratons. The first configuration is without resistors divider and by connecting ...
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94 views

3v3 Microcontroller controlling a MOSFET that needs 5V

I'm designing a heater controller that has a primary input voltage between 12 and 24V. Everything except the heater runs on 3V3, including microcontroller, LED's, potentiometers and the MOSFET. The ...
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144 views

electrolytic capacitor [on hold]

if i changed a 63v 1000uf electrolytic capacitor for a 35v 1000uf what would happen its a main smoothing cap on a power regulator board thats running @ 67v dc 8amp and i want to reduce the voltage ...
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1answer
59 views

bypass a low voltage shut off [closed]

Is there a way to disconnect or bypass a low voltage shutdown operation? I have a factory made electronic shooting gallery (toy) that runs on 4 AA batteries. I want to run it to a steady 6VDC supply ...
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1answer
53 views

Dual Dc regulated voltage circuit design

I'm working on my term project which is designing a dual DC regulated voltage that gives a DC voltage between +or-ve 3 to +or-ve 15. I have completed the testing for positive DC output part, but I ...
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1answer
87 views

Different pin assignment for same regulator

I got 2 samples of LP2905CZ (TO-92) voltage regulator. First sample is made by TI and second on by On Semiconductor. Links of the datasheets: On Semiconductor TI Due to ignorance, I just read the ...
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4answers
238 views

LDO or Switching for 24V Input, 5V Output

I have a 24VDC supply that needs to be regulated down to 5VDC to power an Arduino Mega and a XBee Series 2 module. How would you choose between a Switching Regulator (LM2576T) and a LDO Regulator ...
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2answers
63 views

Stepping down 12VDC linear power supply to 9VDC

I have a +/-12VDC power supply that I have built up for testing simple audio circuits. It works just fine for me now but I would like to add a permanent +9VDC leg to it. I have never seen a scenario ...
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71 views

Please explain the circuit (current regulator test circuit with Zener diode)

my mind needs refreshing so could someone please help explaining analysis of this circuit. It is used for testing a current regulator (LED driver circuit) ('I' in the image). The regulator current is ...
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1answer
50 views

Negative voltage across ground points under load

All, I have a circuit with an Exar XRP7659 5v 1.5A regulator and a Torex XC6210B 3.3V LDO Regulator. I am using this circuit to charge USB devices at full current and have noticed that when the ...
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2answers
29 views

Can I replace U1 (79L05) -5V 1MA with MC7905CT -5V 1A without problem?

I am assembling a metal detector kit of parts. http://silverdog.co.uk/images/BuildingMinipulseRevD.pdf At the end of stage 1 which involves building is 'a simple linear regulator that provides the ...
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2answers
51 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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46 views

Constand output voltage from batteries / rechargable batteries

I'm trying to make myself a battery pack for my DSLR camera. The original battery of the camera has 7.2 V and 1200 mAh. I've also bought a coupler ( a dummy batterie for external DC input ) which ...
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12 views

Reprogrammable Remote Power Supply Raspberry Pi Monitor and Control

I currently have a reprogrammable power supply (HCS-3400) hooked up to be controlled remotely from an control/monitor app provided by the power supply company, Manson. The supply is connected via USB ...
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2answers
46 views

DC to DC step-up boost converter compensation pin, what values to use?

Okay, so I decided on a DC to DC boost converter but am having some difficulty figuring out what values to use for the compensation pin capacitors and resistor. The data-sheet really does not go into ...
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1answer
56 views

Use reference voltage as power suppy

I am using MCP3202 which does not have Vref as independent input. The datasheet states that the current consumption is: 550 μA max. active current at 5V Can I ...
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1answer
53 views

3.7V to 9V DC to DC boost step-up converter design help!

I need serious help choosing an IC for my project. I need a step-up boost converter to power my device from a 1000mAh or 2000mAh lithium ion battery. So far I have measured that my device only draws ...
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66 views

Is there a voltage buck converter which also boosts output current?

Application: solar USB charger. I have a 9V solar panel. I use a buck converter circuit to bring it down to 5V before going into the USB battery charging circuit. Exact components: ...
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52 views

How to regulate voltage into two variable outputs?

I'm thinking of building a control voltage generator for a synthesizer. Basically I want to control two pitch control voltages with variable resistors, something like this: R1 needs to control only ...
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1answer
79 views

Regulator circuit design

I need to design a regulator for my thesis, but I really need help, Please! The topic: - A temperature regulator for a small fridge Some details: - the regulator has to control a peltier element ...
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1answer
39 views

Need to make sure Thyristor switches off with rectified AC

So I have full-wave rectified AC from mains and the following circuit which is basically a AC dimmer that takes slices of that for a much lower total average voltage. (Voltage source is labeled as ...
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3answers
59 views

Brown Out Problem in Raspberry Pi Over Power Tether Cable

I am in the middle of making my own ROV with six DC motors as the thrusters. The main controller inside the ROV is a microcontroller that is connected to Raspberry Pi that can send and receive ...
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2answers
40 views

Potentiometer with No Minimum Resistance

I'm looking to create a variable current regulator with the LM317 using 1-turn pots. I know that I am going to need to have a resistance of 1.25 Ohms to have a current of 1A, which I want to be my ...
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2answers
103 views

Practicality of this LM317T PWM Voltage and Current control circuit

Ive been trying to design a LM317T power supply with a PWM (Arduino MCU etc) adjustable voltage and current limit. After various circuits, videos and tutorials i have designed the following circuit in ...
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292 views

How can I protect this 48VDC device from overvoltage?

I'm powering this isolated DC/DC converter from a power supply that is a nominal 48V, but could potentially reach a maximum voltage of 56V. The datasheet for the converter says that the absolute ...
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39 views

Battery charging via Buck or LDO?

I am supposed to charge a Li-Ion battery (12V 50Ah) and then discharge it over a period of time for testing purpose to measure its efficiency. And this charging and discharging is to be done using ...
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2answers
43 views

How can I get this PMOS to turn off?

I have a 2V regulator circuit which is used to drive a microcontroller (EFM32G222F128). On the output of this regulator I have a delay switch type circuit (see image below) which is used in order to ...
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1answer
59 views

Step-down Regulator Voltage Drop / Frying

I'm trying to implement an Exar XRP7659 on a breadboard to step 17V to 5V @ 1.5A. The regulator is rated for 18v. Now, I have the circuit wired up and initially the output voltage is 5V on the ...
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1answer
128 views

Dropping 12V to 7.4V

I'm trying to power up my NXT Mindstorm Brick which needs 7.4V (at least, that's what the battery output is) with a 12V Power Adapter. I'm doing that because I want a constant supply from the socket ...
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1answer
73 views

Designing E-Cig, need some help with the schematic and components [closed]

So I'm in the process of gathering all the parts needed for an e-cig (vaporizer). Will be using a Lithium, 3.7V nominal battery, heating up a coil that will be somewhere between 1 ohm and 2 ohms (this ...
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1answer
22 views

Peak current requirement for switching logic

Is there a way of estimating peak current requirements for sets of logic gates? This is to qualify the regulator. I have a Gumstix Parlor board with a 1.8V regulator (MIC5247) at 150mA on it. This is ...
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1answer
40 views

voltage regulator connected between positive and negative voltages

I'm kind of new to the world of electronics, so bear with me. I need to regulate +24 volts down to about +21 volts (for supplying a really pretentious heating resistor). I already have the circuit for ...
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2answers
79 views

Passive voltage drop from 6V DC to 5V DC for 3W circuit

I plan to put an Arduino onboard of my hub-generator powered bicycle circuitry. Currently, I have a circuit consisting of: 6V/3W AC hub generator (variable frequency and power); Rectifier bridge; ...
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1answer
50 views

What would cause a zener shunt regulator to have Vout < Vz?

I'm restoring a old motorcycle and the headlight is very dim. Upon inspection, there appears to be a shunt regulator. I infer that the part they call the 'regulator' in the diagrams is just a zener ...
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62 views

Can I use a transformer to drop a DC voltage?

Can I use a transformer to drop down the voltage from a generator? Or should I just use a regulator? The generator outputs about 9.3 V and I need about 5 V, and I want to conserve power.
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1answer
63 views

Voltage regulator identification?

I need to identify what I think is a voltage regulator. It is a TO-220 package with 023499 at the top and 8509 below it with KAG below that. Can anyone help with this? It is in a battery charger.
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1answer
72 views

Reducing the voltage into a speaker passively

Well not high power, low resistance. I have an unusual situation where I am directly driving speakers from an oscillating signal ( its not audio its more like a buzz ) I only have 2 inputs 12v ...
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2answers
79 views

Question about LDOs and the practicality of this application

I'll try and keep this as organized as possible so everyone can understand my thought process as easy as possible. I will be using a 12V 5A switching power supply (available on eBay) to convert my ...
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75 views

Old power supply regulation board will not trim to spec

I have an old voltage controlled synthesizer that relies on accurate power supply voltages (+/-) for everything to run in tune and so it can interface to other similar instruments. Yesterday I opened ...
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1answer
74 views

Voltage step up for bidirectional current source

I will be using a circuit similar to the following to create a bidirectional current source driving a max load resistance of 10k at a max of 2.5 mA. (based on this article ...
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4answers
113 views

Output of voltage supply drops to about 1V from 5V

I have fabricated a PCB board. It consists of the following circuitry: 9V - 78L05C - (a circuit consisting of resistors, opamps, comparators, analog multiplexers). I have attached the pictures of ...
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2answers
153 views

Selecting a transistor for high-side switching at 5V with a 2A load current

I'm doing a high side switching of 5V 2A load and will be ON or OFF for long time(1-10 hours). Now I'm confused about which transistors should I use ? or MOSFETs ? Do I need heatsink ? I really ...
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2answers
82 views

Are there any high voltage (14V) MCUs? [closed]

Switching regulators and LDOs are not an option, for complex reasons. Are there any MCUs which can tolerate a 14V supply voltage? I'm currently looking at 4000 series logic to do what I need, but I ...
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1answer
32 views

Selection of charge controller to charge Lithium Ion battery

I have a DC generator with an output voltage of 27.5 Volts and current of 102 Amps. I need to use this charge my 24V 100Ah Lithium ion battery. So, I need to put a charge controller in between to ...
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1answer
46 views

Can you use a the vout of a regulator as the cathode and your full voltage as anode?

I have a servo from an rc car with 6 wires, it turns out the servo controller is built into the RC Car with a bad board. I have a motor, a gear box and a 10k pot attached to it. I'm trying to build a ...
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0answers
27 views

Will my potentiometer provide enough amperage for my h bridge?

I am sending pwm requests to my H-bridge from an arduino. Each pwm signal is a precise so I need to have the h bridge drive it by that specific amount. I want to use 5V for the h bridge supply, so i ...