Tagged Questions
0
votes
2answers
71 views
Warm voltage regulator [closed]
Why is my voltage regulator get warm while my car is not running "68 corvette" battery is also going dead, is it the regulator or another problem?
2
votes
4answers
113 views
Voltage Converter's GND Problem
I am confused about the ground part of a voltage converter.
This is a typical voltage converter. As you can see the the main voltage is 230V, and the output is 5V. Look at the output 0V, which is ...
1
vote
1answer
107 views
Keeping the output of a heated LM317 constant
I have built a power supply using an LM317:
simulate this circuit – Schematic created using CircuitLab
When the supply is on for a rather long time (several hours) with a respectable ...
1
vote
3answers
172 views
How to build simple 12v .5a regulator
I'm building a solar powered light. The idea of this light is that its output is proportional to the brightness of the sun. At night, no light. During daylight, full light. So it's basically as simple ...
1
vote
1answer
38 views
Regulated power supply from thermostat to zigbee module
I have a thermostat that outputs a DC power supply for a communication daughter board. When I read it with the voltmeter, it reads ~3.9v, but the zigbee module that I want to use requires 3.3v ...
0
votes
2answers
80 views
What formulas do I need to use to design a voltage regulator circuit for a zigbee radio?
I've written the code for my zigbee radios, but now I face the obstacle of getting them onto a carrier board to allow access to VCC, GND, TX, RX via a 4 wire connector.
The supply voltage is 3.712 ...
4
votes
1answer
337 views
Can I connect my laptop that runs on 18.5V directly to a 12V battery?
I have days of electricity outages here (due to war!!!) and I need to use my laptop. The thing is, it runs off 18.5V 3.5A (AC adapter output), so it is expecting 18.5V, what will happen if I connect ...
5
votes
2answers
167 views
Should I use multiple voltage regulators?
I have five devices that need to be powered. I would like to use one DC source to power the four devices. Should I use voltage dividers, voltage regulators or a mixture of both? Also, any ...
0
votes
1answer
88 views
voltage regulators and capacitors
So I'm new to electronics and was looking at some Eagle schematics when I came across the following voltage regulator schematic:
My question is: would it be possible to change the regulator to ...
1
vote
1answer
81 views
Powering the output side of a voltage regulator?
Would powering the output side of a voltage regulator cause any damage to it? (The ground pin would be attached as well) It will not be normally, but I am making a multi-voltage power converter and ...
1
vote
1answer
184 views
Simple circuit Voltage regulator question?
I am trying to build a simple circuit that takes a 9v battery through a voltage regulator that outputs 1.5v across a load resistor . The load will be just a piece of metal that gets heated up.
My ...
2
votes
0answers
89 views
7805 5v regulator outputting 4v [duplicate]
I'd like to start out that this is my first ever electronics project. I built a 5v power supply from here, using a 7805 5v linear regulator. the only problem is that it is outputting 4v instead of 5v. ...
3
votes
3answers
145 views
Do I need to use any external parts with a voltage regulator?
I have recently bought a voltage regulator (link, specs, and datasheet below) and I am regulating a AC-to-DC 9v power supply into 5v with as little components as possible. In the datasheet, all of the ...
4
votes
1answer
261 views
Converting and Stabilizing output voltage of a dynamo hub
Preface - I don't know much about electronics :P
I have ordered a Shimano dynamo hub for my bicycle. I have done a little homework and here are my findings about it:
The output of the above ...
1
vote
1answer
244 views
What does a bad voltage regulator look like?
I have a 7805 5V regulator here and it has a white like substance on it, kind of like when a AA battery leaks acid. Is it bad?
1
vote
2answers
149 views
Automobile Project (Electrical Parts Requirement)
I'm looking at putting together a circuit board to be used in an automobile. It will only be connected to a 12 V and ground. Everything else will be internal to my board.
I was planning on putting a ...
1
vote
4answers
151 views
powering 12 v lights from an electric fence
I have an electric fence running around my farm. I would like to be able use this to power a number of 12 v lights along the road so I have a ready source of light, especially since the electric fence ...
3
votes
3answers
210 views
Voltage regulator 'hiccups' when gate pin of MOSFET is touched
I've been struggling with the following circuit which includes a Raspberry Pi:
That's a 5V voltage regulator (with protective capacitors), and a DC motor over on the right, and an IRF510 N-channel ...
5
votes
3answers
178 views
Dropping voltage for red channel on RGB LED
I'm looking at a Multicomp OSW-8349 RGB LED, which has a Vf of 3V min / 4V max for the green and blue channels, and a Vf of 1.8V min to 2.8V max for the red channel, at 350mA. I'm planning on ...
0
votes
1answer
169 views
LED setup with 110 standard outlet [closed]
I am attempting to grow an indoor garden. I would like to purchase LEDs to help grow my plants. Can you help me understand everything I need to power my LEDs (and not catch anything on fire). From my ...
0
votes
1answer
176 views
Atx psu 7v output
What is an easy way to get 7-7.2vdc from an scavenged atx psu? I had thought about using a lm317 but I'm going to need at least 5-7 amps of current, and the 12v-5v split just sounds like a really bad ...
0
votes
1answer
111 views
Static sound when running amplifier and usb charger off same battery [closed]
I am running a 12VDC 2A Lepai amplifier off an 18V Li Ion power tool battery using a 1.5 maxA step down voltage regulator. All was working fine until attempting to add in a 12V to 5V 1000mA USB ...
1
vote
1answer
296 views
how can I made a 12vdc to 19vdc booster/regulator?
This is a fairly specific question, but I think the answer could probably be applied to various voltages.
I would like to make a circuit that will take in a 12-14volt source (from a lead acid) that ...
6
votes
2answers
128 views
Setting a part's VCC slightly lower than board's supply voltage
I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V.
The ...
3
votes
2answers
175 views
Stepping from 5 V / 1000 mA to 3 V / 750 mA
I'm trying to go from 5 V, 1000 mA, which is a USB transformer for Apple devices, to 3 V, 750 mA (which is a small camera I have). I have purchased a NTE1904 3 terminal volatage regulator which 3.3 V, ...
6
votes
1answer
400 views
Center tap split supply question
Lest's say that I have the following setup:
a split supply (using two voltage regulators: a positive and a negative one) connected to a center tapped transformer (12-0-12). The output of the ...
-5
votes
1answer
182 views
diode nightmares
Let me start by saying I am a complete amateur trying to stumble my way through some pretty basic PCB design, and I have run into a problem selecting diodes. The PCB I am designing will be for some ...
1
vote
1answer
264 views
LT3080 regulator question
The datasheet of the LT3080 voltage regulator says that "For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage."
What exactly does this mean? How ...
1
vote
5answers
601 views
How to make 95%+ efficiency voltage regulator?
I need to make an 11 volt voltage regulator. I would really like this to be step-down, not a linear voltage regulator because I am going to be drawing between 1-2 amps at 11 volts, and if I was using ...
11
votes
3answers
550 views
12V DC to 5V DC converter
I got this circuit from internet. I don't know why the capacitors are installed in this circuit. Can somebody tell me the reason of these capacitors..
1
vote
2answers
150 views
Simple Voltage Calculation
Could you please help me about calculating the voltage on the 100 ohm resistor. I know the result is 0.708 V but how could I calculate it, is there an easy way for that?.
0
votes
2answers
607 views
12V voltage regulator with the least drop out voltage
I have a DC adapter rating 12 V 750 mA. I broke open its case and saw that its rectified but not regulated.
I need 12 V for my design and do not want to buy a transformer. Do you know ...
0
votes
3answers
162 views
Lower Voltage RF Amplifier for 400 MHz
I'm using this Mitsubishi RF amplifer in a portable device. The Mitsubishi amp operates well between 7V - 9V.
But I have to interface with a power source that gives 1.5V, and stepping 1.5V up to 7V ...
0
votes
1answer
452 views
Is it possible to create a zener based spike filter?
I am analyzing this circuit of an ECU of an automobile and I found it's difficult to
understand it's LM7805 was protected from spikes. You could find that 7805
configuration block in the right bottom ...
2
votes
1answer
265 views
3 stage/cascade voltage regulators
I am working on a project that uses 3 voltage regulators from a 12V input.
INPUT 12V >>[8V reg]>> 8V >>[5V reg]>> 5V >>[3.3V reg]>> 3.3V
I am wondering if is it safe to use an external power supply ...
0
votes
2answers
104 views
Where can I learn about electronics? [closed]
So I was following thenewboston's robotics & electronics videos but it turns out that is another series he has abandonded and I want to keep on learning!! Now I know about 1/2W resistors, ...
3
votes
2answers
1k views
LM317 - bringing down to 0 volts (with a uC)
I am wanting to build a custom power supply for myself, and am having trouble understanding how to drive the adjust pin with a microcontroller.
The datasheet for it is here: ...
2
votes
2answers
958 views
I need to convert +5V to +12V with minimal components and PCB space
I need a +12V reference voltage for an op amp circuit, so it doesn't need much current. I just want a simple surface mount device that takes up little room, and doesn't need a ton of passives or large ...
2
votes
2answers
416 views
Controlling analog volt-meter display
I know that it is possible to generate higher voltage from lower voltage source, I just don't know how ...
Anyway, few days ago I got this:
...
1
vote
3answers
436 views
LM317 Ripple Rejection
I've developed a circuit for my model aircraft, which requires 3.3V @ 100mA. My aircraft uses a 3S LiPoly, which ranges from 9V - 12.6V. When the motor is off, the 3.3V supply is good; very low ...
1
vote
1answer
238 views
How could I create a high-precision voltage with the atmega128?
In my solution i have to replace an 10 turn potentiometer ( 5 K Ohms ) with a digital circuit. the potentiometer is dividing a voltage between 4v to 21v. so it seems if i could generate a voltage ...
3
votes
4answers
2k views
Resistors values to use with LM317
I know that ratio R1 to R2 determine the output voltage of LM317. E.g. R1 = 200, R2=330 ohms will produce about 3.3V. My question is, what if I use 2K and 3.3K for R1 and R2? What is the impact of ...
2
votes
3answers
191 views
Can an alternator cause components to run at a higher-than-rated voltage?
Given that the voltage regulator on my motorbike is set to 14.3 volts (so that it charges the 12 volt battery effectively) and given that the alternator is what provides power for the electrical ...
2
votes
2answers
318 views
Voltage Divider
I need to cut the voltage going through a 1/4" TRS cable (at the connector) by 1/2 (and I need to do this to about 14 cables). I understand that this can be accomplished with two 4.7 kohm resistors ...
3
votes
2answers
4k views
5V to 3V, calculate resistor value (or use diode?)
I want to connect this dv motor to the 5V output of an Arduino board. Of course I need to get the 5V down to 3V in order for the motor to function correctly. I've read that I could use a diode with ...
8
votes
2answers
804 views
Is it normal for DC wall adapter power supplies to provide voltages above the nominal ones?
When I measure a 9V DC wall adapter power supply with a multimeter it shows 11.8V. When connected to my board this voltage lowers to 10V. Is this normal? Should I be afraid of toasting my 1117CD-5.0 ...
2
votes
1answer
235 views
Cheap 500mV reference
For a project, I need a 500mV reference.
Some requirements:
Relatively low cost.
Small size. Preferably surface mount.
Supply from 4.8V to 25V.
Accuracy ±5% or better
Stable over voltage (that is, ...
5
votes
3answers
171 views
Close enough for voltages?
I want to extend the use of a camera. The camera currently uses a special li-ion 3.7V 1000 mAh battery. I could grab a couple of those batteries, wire them up in parallel, and that'd work just fine. ...
