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5v and -5v from 9v? Answered

How can I get +5v and -5v from a single 9v PP3? Not 4.5v, I could do that easily with a voltage divider. Preferably using only passives and discretes (Inc. voltage regulators)?

Question by andy70707    |  last reply

A 5V zener reduce the voltage in 5V or regulate it in 5V? Answered

I neede to know if a zener diode regulates the voltage or reduces it and also how can I know what type of zener it is.

Question by tgferreira184    |  last reply

If I put 5v in a 5v voltage reg, will 5v come out?

What kind of voltage drop should I expect if I put 5v in a 5v reg?

Question by nepheron    |  last reply

-5v Voltage Regulator

I want to make a -5v Voltage Regulator... Does anyone know if I replace the 7805 regulator with a 7905 would that be enough, or would the capacitors have to be different values?5v Voltage Regulator Schematics

Topic by mrshow555    |  last reply

5v to 12v convert

Hello, I want to connect a portable solar powered rechargeable to 2 DC fans of 12v to cool my car. 1. I have 2 options of portable solar powered: (A) 1500mAh, outputs: 5.5V / 800mA (B) 2000mAh, outputs: 5V 500mA     which one is preffered to connect to those PC fans? 2. most of the PC fans are working at 12v. I don't quite sure if I'll build simple 5v to 12v regulator it will works and produce enough airflow. Thanks.

Topic by ashakif    |  last reply

50uV to 5V amplification

How to amplify 50uV to 5V using LM324n op-amp

Question by Pranay ReddyK    |  last reply

simple 5v regulator?

Today i made a shaking generator for a shaking flashlight.i am using a 5.5v 1F capacitor as storage device.but output of  the generator is 3v~6v i can regulate the output ≤5v?.i am looking for most simplest and cheapest method. can i use a resistor?

Question by vina1991    |  last reply

5v battery backup?

Hi, I have a 555 timer circuit running in monostable mode which I need a battery backup for.Anyone have a simple, reliable circuit that can achieve the following results :1. Switch power between the 5v cell phone charger and the battery in the event of a power outage. The "switch" needs to be seemless otherwise it will trigger the monostable as it is set to trigger or re-trigger whenever the power goes off and on again.2. Charge the battery when the power is on.3. Stop charging the battery when it is fully charged.Any other suggestions will be much appreciated. I am not rigid on the design and use of parts, although....the cheaper the better without compromising on reliability (of course).This is for a security system that drives two lasers, a camera and a cell phone. Not sure if the cell phone battery can be used to power the "backup system" as well as run the cell phone.Thanks in advance.GK ;)

Question by GhengisKhan1981    |  last reply

Where find 5v regulators?

Hi!Where can i find 5v or 12v voltage regulators?

Question by ondrikczech    |  last reply

Help! (5V psu problems)

Help!I'm trying to make a 5V psu for programming my new (but not so shiny v_v) ATtiny2313'sI've got the circuit shown below set up, but I'm getting out around 5.6V, when the spec sheets say that I'm supposed to be getting out 5V (+/- .2V) I'm using the LM 340t5, just 'cause I don't have any other regs (except for the MC78M05CT, which is basically the same thing.Any Ideas?!EDITI know what was wrong - it was my meter, it really was 5V all along ;)

Topic by T3h_Muffinator    |  last reply

5v to 12v step up

Hi, I am looking to power some led's by USB. Problem is that the led's are 12v. Here are some example led's:;=item43a76471ea#ht_3932wt_1396 Would something like this do what i want it to do?:;_source=gbuk  Also looking at the step up booster i have no idea where i would solder/connect wires to the device? Any help would be appreciated. ItzMar

Topic by ItzMar    |  last reply

will 5v stepper will work on 12v?

In ""   the datasheet for pl15s-0120(Stepper of dvd drives) says it operates at 5V , Didn't the a4988 gives 12v out ? , will it gonna work ? (posted comment there but no one replied .....)

Question by _Boltz_    |  last reply

4.7uF capacitor 5V or lower????

Do someone know where i can buy a 4.7uF 5V (or lower) in europe????

Question by Dannne11    |  last reply

help with 9v to 5v to 3

I am trying to make someting liek this guy made here where can i find a circuit that will give me outputs of 3v 5v and 9v

Topic by DELETED_kclv1988    |  last reply

usb 5v to 3v fan

I'm considering running a 3v fan from a 5v usb. can i simply put adequate resistance in series to reduce current to acceptable levels?

Topic by Toga_Dan    |  last reply

battery backup

I have a really cool sunstech weather station but when the power goes off it loses time date and weather prediction. I live in Spain and we are prone to daily power cuts. I need a low power 5v back up system to power it. Any ideas welcome

Topic by malchall    |  last reply

5v relay module with tv usb

Hello there! I'm sorry if someone already asked this question but I can't find it! I would like to connect 2m led strip to my tv usb so it turns on and off with tv. Can I use this kind of relay (;=item5b016763a7 ) to do it?  Thank you in advance!

Topic by tosho82    |  last reply

Converting 12v DC to 5v DC

Greetings, I’m very new in electronics. I would like to connect my analog camera that uses 5v dc to my car battery. So I need your help to make a voltage converter. From what I have understand searching the web, I will be possible and very easy actually. All I would need is an opamp and some resistors?!!! Right? So any diagram or anything that you can help me with will be more than appreciated. Thank you for your time reading this. Best Regards P.S. I hope I’m in the right place writing this topic  

Topic by toqilula    |  last reply

zener diode (limit 9v to 5v)? Answered

Can i use zener diode  to limit voltage from 9v to 5v? ( i would use 5v zener diode ) can this work? what else do i need to use? and  is this way efficient? i was thinking to power my phone with this or to charge my light

Question by tealk    |  last reply

I'm using a 5V boost regulator?

To charge a cell phone battery.  BUT maximum current is 200 mA.  That's not enough current I'm assuming, right?  I need a continuous output of 5V but my students are most likely not going to get 5V from a shake charger (neodymium magnets going in and out through a coil of wire) which is why I was going to use a LM7805 but that needs 3 volts more than the output voltage.  Any suggestions??  Thank you!

Question by mckywer    |  last reply

USB 5v step up to 12v?

Is there any such thing as a device that will step up 5v from usb and convert it to something else like 12v? I say this because I have a solar usb charger that charges a 2600 mah battery and outputs 5 v at 800mah to usb. i wanted to step it up so it could be used for other things.

Question by XBLmonster    |  last reply

Variable speed on a 5v brushless fan

Hi everyone! I have a 5v DC (0,15A, 50mm x 15mm) computer brushless fan that I want to power with a battery pack (4x AA rechargeables= 4,8v) or the MightyMinty Boost. This small blower is meant to be a part of a woodgas stove, and will bring air to the fire through a small duct. I'm looking for a circuit that would allow me to control the speed of the fan and the airflow. Kinda like a dimmer switch. Is there a readily available switch or devices that I could plug between the batteries and the fan? I guess the RC guys out there know a few thing about variable speed controller. I'm a newbie at this; I don't what to build a circuit from scratch, unless it's really simple. Thanks

Topic by jemor143    |  last reply

convert 5v DC to 3.3v DC?

Hello would somebody help me with this please, I am not much of a "electronic" kind of guy so this is a big problem for me. I lost the power adapter of our office router WRT54GC (linksys) and my boss has his finger cross on me. I only knew of its power which is 3.3volts 2A DC. From my location, it is very unlikely to obtain a replacement or an equivalent adapter. I have salvaged a power supply of and old printer that gives off 5.0V 2A DC but the router would not run with this voltage. I will really appreaciate it if somebody would be able to help with a step by step explaination on how to lower the 5v to 3.3V . Thank you very much.

Topic by gincasty    |  last reply

Looking for a 5V valve to be driven by ARDUINO

Hi everybody, I am working on a project to make an automatic watering system driven by arduino. I am looking for a valve which I could operate without any extra power supply but the 5V from the ARDUINO. It would be perfect if the valve could be in the range of the 6mm for tubes connections. As my project will rely on gravity for water movements, I don't want to use a pump or whatever active device. Just some standard batteries connected to ARDUINO. Do some of you know such a valve? I have looked on the net without any success. I have found loads of watering projects using arduino but none with the same phylosphy. If you know one, please let me know. Regards,

Topic by BaptisteL8    |  last reply

9v to (5v-3v) for pic 16f628a

Problem: I have a 16f627/628 (runs between 3 and 5 volts) that needs to work in tandem with another device (call it D) running at 9, direct current, (active for 1 second in 30 or less frequent). Upon hooking up a number (of descending in size) resistors (without D connected) with the supply and 16f6xx the 6 LED's powered by the 16f6xx do not turn on unless resistance is extremely minimal, and voltage is well above that advised in the datasheet (not to mention making the pic reset itself every 10ms). Can anyone tell me how I might run the 16f6xx from a 9 volt battery, and explain what was going on? This may seem unforgivably dim to anyone who knows but unfortunately I'm more a software guy learning hardware as I go along. Any help would be much appreciated, Thanks Andy

Topic by andy    |  last reply

What t is the difference between the -12v and +12v, -5v and a computer power supply? Answered

 I am building an AC to DC power supply based on several Ibles and I am not sure I understand what the 2 different voltages are (-12v, +12v; -5v, +5v ....) Thank You!

Question by missplumeau    |  last reply

"5 volt limit" circuit? Answered

Is there a circuit that will take a range of voltages and make all of the voltages that are over 5 volts be 5 volts  like so: 3.5 => 3.5  4.2 => 4.2 4.9 => 4.9 5.1 => 5.0 6.3 => 5.0

Question by flybye22    |  last reply

Wiring diagram of B0505S-1W 5V to 5V converter DC DC power module Isolation

B0505S-1W 5V to 5V converter DC DC power module converter 1000VDC Isolation. Need the wiring diagram of this component.

Question by Sayan_trex    |  last reply

12v and 5v Power Supply from 240v Answered

I am creating a home automation device that uses an arduino. The devices are connected to a relay. The real problem is I am using a using a DTMF decoder with the relay, while the relay works only with 12v power supply the DTMF decoder works only on 5v input (USB from computer to arduino). The devices that I know of are capable of converting a 240 v to 12v or 5v not both. What should be done so that I am able to get a 12v and a 5v from a normal 240v household power socket?

Question by NirmalMRaj    |  last reply

How to convert 12V to 5V for incar use ?

I need to create a cable that will run from my car battery into a device that runs on 5V DC power. It needs to look like this: INPUT: 12V car battery Simple bare +ve and -ve wires OUTPUT 5V 1.25A barrel connector 5.5mm (I beleive) like this one:

Question by SamC17    |  last reply

How can convert a12v down to 5v?

Question by niru21    |  last reply

How do I wire a 5v regulator?

I am just hooking up a wireless weather station and it uses 4 AA batteries to power it. (it's a 3v supply to the unit) I want to use a solar panel I have to power it. It's a very small solar panel with a 15-16v output and really low current so that is not an issue. Anyways, I want to use a 5v regulator to charge rechargeable batteries in the transmitter, but I've seen capacitors used in the wiring and what is that about? Also, it's 3 pins, and the middle is ground, but how do you wire it and do you even need it? Thanks

Question by tinstructable    |  last reply

Does 5V in a ATX PSU give 2A?

Looking for a power supply for my USB Hub, and I think I might found it. My PSU in my computer has 5V and 2A for VSB and another one with 5V and 25A. So my question is: does a Molex or floppy connector give 5V and 2A? Any power issues connecting this to my hub?

Question by BIO Wolf    |  last reply

how to reduce 5v dc to 2.5v dc?

I need to reduce a 5v power supply to 2,5 v for a certain application, I've got a converter that can do it, but want to do it using some electronics any ideas?

Question by fjchorn    |  last reply

How to build a 12v to 5v conversor with a zener?

I'm developing a shield for my Arduino Uno and I want to add in it an external power supply. The power source I want to plug in it has four connectors: 5v, gnd, gnd and 12v. The 5v and the gnd pin goes to their respective pins in Arduino, while the 12v pin goes to a 7805 on the shield or to Vin, and the selection is made with a jumper. The only problem is that the connector can be plugged inverted, swapping 5v and 12, which would damage the AT mega. I know zener diodes are useful for limiting power, but I don't know how to use it. I need a simple circuit in which I can plug my 5v supply and it gets 5v to the chip, and in case I plug the connector inverted, to limit its power to 5v to prevent damage or to shut down the power. I can’t use the 7805 on both pins, because it would deliver something like 4v or less if powered with 5v. And something like a led to indicate that the connector is at a wrong position would be nice too. Thank you.

Question by senitram    |  last reply

Coto 9202(150hom) 5v reed switch

Please can any one help.I am looking for a COTO 9020 5V reed switch with an internal resistance of 150ohms.I haven't had any luck in locating one. I was wondering if there was a alternative available to replace the COTO 9020 5V reed switch with an internal resistance of 150ohms.many thanksMike

Question by MikeC510    |  last reply

How to power an opamp(with -5v) form USB?

I`m making a dac+amp with usb input and headphone out. I`m powering it from USB. The USB controller and the DAC uses 5v and 3.3V, but the opamp(LM4562) uses +-5v. How could I get this differential voltage form the 5V of the USB, even if i get less current. If you can give me a good IC, it would be great, but if you can give me even a schematic (+IC) would be awesome.

Question by fmada    |  last reply

Will a USB Mp3 player charge with 5v and 88MA? Answered

Will a USB device Mp3 (usually 5v and 100-400 mA) player charge with 5v and 88MA? Will it take longer to charge? Or will it overload the charger and break something? Will a fluctuating amperage, always below the device's requirements, damage the device's LiPo battery?Thank you! I'm going to make something cool!

Question by nepheron    |  last reply

5v stepper motor ? How to make it work ?

Hi I recently bought a 5v stepper motor ? what should i do to make it work .I want to fix it to my camera to move it in right and left directions ? how do i start to do this ?

Question by vasan406    |  last reply

will this circuit work as ups for my 5v device? Answered

The circuit is shown in the photo If i need to make changes in schematic write in comment

Question by Suraj Grewal    |  last reply

Charging batteries via a 5v USB connection

I am working on a project that requires 4 AA batteries. I would like to discuss if it is possible to create a charger that would charge the batteries (rechargeable AA's of course) via a 5V USB cable. The unit itself would not need to use the 5V USB power to operate, just to recharge the batteries when not in use. Does anybody know if this is possible? Please let me know if this a vague question, as I am in no means a professional in this area. Thanks in advance to any insightful comments!

Topic by honduhridr    |  last reply

5V Nextel Phone Charger OK to use?

I have a phone charger for my Nextel phone. On one end is a wallwart for a standard US outlet. The other end is the proprietary Nextel connector. The phone connector end was unfortunately broken, but fortunately I have a spare :) I believe the rest of the rig works fine, and rather than throwing it out, I took a look and it was rated 5V @ 800mA DC. AFAIK, 5V is what most USB devices work off of. Would it be suitable if I snipped the end off and rewired other connectors on to this and used it as a charger for other devices? Thanks in advance!

Topic by mikesty    |  last reply

18v power spike on a 5v power supply Answered

I'm trying to build a power supply for some ws2812b leds ( 3 projects at nearly 300 leds Requireing 18 amp)The problem is that the only power supply large enough to handle them (5v 40 amp) has a 18v spike at the startup.Any ideas for a delay circuit that is 18v tolerant? Even having to push a button after the circuit is energized would work for me

Question by Wired_Mist    |  last reply

Analog sine wave generator? (0v-5v)?

I am wondering how to create an analog (NOT digital) sine wave from 0 - +5 volts (Not -5 - +5). If you could, post a schematics diagram, or send a link to a page with the schematics. It has to have a variable pitch. Thanks, josh1324

Question by josh1324    |  last reply

Control RFM69HCW with Adafruit's Pro Trinket 5v?

Hello, I'm having an issue controlling the RFM69HCW board ( with the Pro Trinket  5V ( The issue is when I go to compile an example code, the SPI class gives errors such as:  ...\Arduino15\packages\arduino\hardware\avr\1.6.12\libraries\SPI\src/SPI.h:250:27: error: 'SPIF' was not declared in this scope        while (!(SPSR & _BV(SPIF))) ;                            ^ I cannot find any help online after searching for awhile. If anyone could give me some insight on possibly how to get past using the SPI library or anything like that, that would be great! Thanks!

Question by bigjohn412    |  last reply

Finding an appropriate heatsink for 5V 3W LED? Answered

Hello, I have bought some 3W 5V leds, and now I have to dissipate the heat they produce. I am thinking of using an xbox 360 GPU heatsink i have laying around ( ), cut in apprpriate size. Then I would glue the led with thermal epoxy to it.  Can somebody suggest an adequate size for the heatsink? I can't find any info around. I have other heatsinks as well, I would rather not buying a LED heatsink if that's not mandatory. Thanks in advance :) Picture of the leds attached, they have no board to screw them with.

Question by en_rov    |  last reply

Building a 5V or 12V powered in-line preamplifier

I want to build an in-line pre-amplifier with a 3.5mm in and out jack.  What I want, or at least think I want, is a simple booster that provides a small, but relatively even gain boost from an MP3 player into the main amplifier. Something along the lines of this: However, I would like to be able to power it off of 5V USB or off of the 12V coming into the cigar lighter. What I'm effectively trying to do is get enough gain on low volume spoken-word audio coming out of my mp3 player so that I don't have to crank the stereo up to max.  Does anyone have any good sources for instructions or advice for this sort of thing? Alternatively, someone can tell me if this is a fools errand to begin with, and that I aught to be taking a different approach altogether.

Topic by wildgunman    |  last reply

Variable USB Power Supply (5V 2A)

I was looking to either build, buy, put together (kit) a Variable USB Power Supply similar to the one that I saw on the EEVBlog ( I really liked the compact design of his version, but he never finished it, so I can't buy that kit ;-( Is there a simple way to put together something that is protected (so I don't kill the USB socket I get power from) and has a Variable Volt and Amp adjustments knobs/buttons. I've looked at getting a full size Bench Power Supply, but would love to just have one so that I can power from my laptop or any of my million Micro USB power adapters (5v 500ma through 5v 3A supplies). My first project is something I need to eventually run off of AA batteries, but I didn't wanna keep on re-charging the batteries while I test my circuit design. Would rather have a constant source of 1.25v-1.5v power during the prototype phase. I'm just now getting into Electronics, so please take it easy on my poor little brain. Hopefully this hasn't already been asked, didn't find anything in my quick search through the forums.

Topic by drofnasnhoj    |  last reply

Dual voltage switch, off .5v on 4.5v?

Good day, I have run into a bit of a problem, the original controller has burnt out  for my light controller and i cant find a replacement, but i was able to while it was working find out how much voltage it needs to run. To the light controller is 12Volts,  It requires .5 volts @ 1amp while the system is in the ready phase and when i press the switch it jumps on 4.5volts @ 1amp and the lights turn on. Ideas i had run a crossed was: Running .5 volts straight to the control and having a switch supply the remaining 4.0 volts but i believe that would double the amperage.   Using a relay but i'm not that electrical savvy. Any help would be great. -Davis

Question by davisar4    |  last reply