Making a power supply.

Hi. I have an amplifier. It needs a 12v-0-12v transformer. I have two 12v adapters. Can i attach these two adapters like this(shown in image) to get 12v-0-12v???

Topic by Shezi007 1 year ago  |  last reply 1 year ago


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 7 years ago  |  last reply 1 year ago


-12v leads to GND?

First off, i apologize for asking so many questions. google couldnt tell me a single thing about what i wanted to know, which was how the -12v is created and why a computer needs it. so i turned to a broken power supply to see is the -12v connects to a IC of some sort, which i would assume creates the strange voltage, confirmed by a datasheet. i completely traced the traces with a multimeter and at one point a capacitor went to ground close to where the -12v connection is on the board, after an inductor of some sort. the trace continued, and lead to a pin on the transformer, much to my disappointment. BUT that same trace was directly connected to ground, so now i am confused, does the inductor type piece createthe -12v? there was a diode as well, but i thought nothing of it or its place on the board.. i have a feeling i should have, shouldnt i? fed up and confused by the power supply, i turned to my motherboard. where the -12v leads to a smd capacitor and then traces from the capacitor, to ground, and nowhere else as far as i can tell with a multimeter and a dark blue motherboard. then i bring up the picoPSU, how do they make the -12v, if it is even made? is there a chip responsible? or a inductor like i found in the power supply? -5v has been omitted form power supplies, so im assuming that the same can be done by -12v, right? and wouldnt you get a -v type measurement if you put the + test lead on the - terminal and vice versa?

Question by zack247 7 years ago  |  last reply 7 years ago



Tube headphone amp

I want to build a tube headphone amp. Is it possible to make a smps (switch mode power suply) to power it? It would be like a mix between old and new technology!

Topic by dwj300 10 years ago  |  last reply 10 years ago


Does anyone know the specifications for the Behringer Xenyx 802 power suply or where to get one? Answered

I have been looking for one as I have recently bought one of these mixers but it comes with no power supply. I have searched the internet only to find the instruction manual which isn't very useful. http://www.behringer.com/EN/Products/802.aspx All comments are welcome. Thank you Oscar

Question by oscarthompson 8 years ago  |  last reply 8 years ago


need circuit diagram for a sin wave inverter?

Good day honorable members pls can anyone help me i want to build an inverter and i need a circuit diagram for an 50Hz 24v to 220v sinwave inverter. Pls can anyone suply me with an circuit diagram for an 2KVA and a 5KVA inverter pls pls help me thank you in advance

Question by rahvin1223 7 years ago  |  last reply 7 years ago


Turn on Dell Latitude laptops without charger

Recently my uncle gave mi 2 laptops Dell Latitude wich he found in his job, but here comes the problem I don't have any charger for they and because of that I can't comprobate if they run. Can I use a Acer charger or a power suply of a desktop to satart the laptops? Any other idea?

Topic by kenyolo 7 years ago  |  last reply 7 years ago


Led light Panel Help!!!!!!Please

PLease help im not a novice in the world of electronics i .e i went to college,although many years ago. Im looking for a the easiest way to wire 200 leds into a light panel...... ie 200 led's in 50 x 40 there 3v leds What be the best way to wire ie,what power suply do i need,resitors etc Please advise thanks jim

Topic by hairyjim 11 years ago  |  last reply 11 years ago


Wine Bottle Lamp / convert to Battery power

Hello My wife purchased one of those wine bottle with the xmas lights in them. But were she want to display we dont have a outlet.  Does any one have a instructable on building a small battery source to plug the lamp into.  Just to be used on special occasions, so does not have to have a long lasting suply.

Question by sgt ammo 8 years ago  |  last reply 8 years ago


I want to run 20-12v leds, witch allready have resistors, what circuit am i best using and what power will i need?ty?

Basicly i want to run 20 5mm uv leds, they allready have the resistors prewired, and state a 12v power source is needed but i wanty to run all 20, what circuit would be best and what kind of power suply and voltage any help would be great chhers

Question by dora0751 8 years ago  |  last reply 8 years ago


i have made 4 bicycle dynamos each gives -2-3 volts .i need a way to combine all this so i can get 1 single big power !?

I have made 4 bicycle dynamos each made using a normal dc motor and each  produce 3 volts .i want to know how should i connect  them so that their powers suplies produced can be combined and which can give me 1 big single supply ?

Question by roboguy22 7 years ago  |  last reply 7 years ago


Problem with my variable regualted dc power supply.

I have a used variable voltage regulated power supply that does not work ; when i turn it on, the Volt meter tops, and if I switch to ammeter, it shows 0amp, if i plug a voltmeter on the female banana plugs there's no juice... I've checked the fuse, it is not damaged. i've also checked to potentiometer with my ohm-meter looks like it's working normally. I don't know what is wrong with it... Do anyone have any idea ?

Topic by lordofthedonuts 10 years ago  |  last reply 10 years ago


Z-5500 Led's blink to music [HELP]

Hi! I got a question about led's beating on music. I got 3 of the same sound systems (logitech z-5500) and i want to add some led's for effect. I've seen some tutorials about soldering it to the + and - but i dont want to do that with the sub because of the music quality. I want to add 60 led's. orange, blue and white and i want them to work from a external power suply. How should i do this? Cause i cant find any instructable on how to do it with a mic. Thanks!

Topic by Gleno0h 9 years ago  |  last reply 9 years ago


Why does my motor is so slow after using two transistors as switches?

Hi guys! As i'm waiting to my H-Bridge to arrive i built this just to play around, but theres a problem. The motor works, goes foward and backwards as i programmed on the arduino, but its incredibly slow, to a point that it can't make the rc car body move. If i connect the power suply directly to it, it goes like a bullet. What  could it be? The circuit is attached. *I'm using a BC546 transistor **All the resistors are 1k ohm ***My power supply is 9v/600mah.Thanks in advance! http://i.imgur.com/lIgNf.jpg

Question by Sowee 6 years ago  |  last reply 1 year ago


Current in IC chip

Hello, It's a bit stupid to ask (I think), but essential to me. From all schematic I readed over intructables I never saw anything or anybody that cared for that. If a IC have a maximum and minimum current to respect ie: 6mA to 10mA, do we even care? Do I need to limit the current somehow? As I said, every schematic I readed never added any resistor or talked about anything relate to limiting the current on the VCC for the integrated circuit. I'm currently building a device that use one 555 timer IC in astable and a few others IC and they are all connected in parralel to the power suply. Thanks

Topic by sxdemon 9 years ago  |  last reply 2 years ago


What is wrong with my flyback transformer? please help asap.

So i have a flyback transformer and i was testing the continuity of the pins and my first two pins were together and then my 3rd and 8th were together and that was it. no other pin pair set it of. i tested every pin multiple times with every other pin and got nothing. my first pair also showed a reading of 2.4 ish ohms and my second pair showed 1.5 ish ohms. what is going on? im trying to find out where to hook up my power suply so i can just get some simple arcs. are those the primary and secondary coils and the rest ground? PLEASE  HELP

Question by PyroTrician95 7 years ago  |  last reply 7 years ago


How do I connect 3 x SainSmart 16-Channel Relay Module to an arduino mega board?

I have seen several posts regarding relay modules and arduino, but none specific about connecting this configuration.  I want to control 48 light bulbs with an arduino MEGA 2560 board. Can anyone help me with the requirements? I mean, I need to know whether I can connect those 3 relays modules (16 channel each) directly to the arduino, if so, which pins should I use. If not, should I use an extension board? Also, I am not sure about the power suply for the whole system. Should I use two power sources? (one 9 volts for the arduino and other 12v to the relay modules?), and how do I connect the power sources to that system? Any help is welcome. Thanks in advance.

Question by GabrielC191 2 years ago


how do i connect a radio control servo and gyro together?

I want to use a radio control servo and gyro to keep my wifi antenna pointing the same way. i live on a boat and have a long range wifi antenna which is like a flat plate one foot square and directional and each time the boat swings at anchor i lose the signal. i want to know how to wire up the servo and gyro to a battery to keep pointing the same way. thanks paul i just want a way of powering the gyro and servo, i can point it the way i want it to face to start with, then i want the gyro to take over to move the servo opersit to wherever the boat swings. i dont know how to power the servo and gyro i know it takes 5 volts which i can give it but i dont want to have to use a reciver just the servo, gyro and power suply.

Question by Poppy_Ann 10 years ago  |  last reply 10 years ago


Is my shematics good ?

Hi there ! I have the project to make a trash compactor. To do this i have a truck wiper motor http://ncr.en.alibaba.com/product/319740439-215097357/180W_Bus_wiper_motor_EMI_EMC_Volvo_bus_wiper_motor_12_24V_NCR_8385_.html ( 180W 24V 30A ) and a worm screw sytem. To control this motor, i've made a H bridge with this transistors https://www.sparkfun.com/products/10213 To control the intensity consumed by the motor and prevent it from burning, i use a current sensing chip http://http://www.evselectro.com/kits-30a-range-acs712t-elc-30a-module-current-sensor-module-3024 To control all of that, i use ATTiny 84. My power suplly is 24V 30A and my µC ( The ATTiny 84 ) use 5v suply so i have to convert a part of the 24V to 5V. To do that i use 7805 but i think it will burn or i will lose lot of energy. I've made the shematics of my circuit and i wonder if it's good or not and what can i change. PS: The two switch in the schematics are end positio sensor. Thank :D and sorry for my bad english :/

Question by retrobotic 5 years ago  |  last reply 5 years ago


Can I use CAT5 for running a 12V DC (Power over Ethernet) to connect to a surveillance camera 12V DC, 500mA? Answered

Hello, I want to set up surveillance camera system in my house.  The house is already prewired with 2 cables (1 CAT5 & 1 Coax RG6) at each end (1 end at camera place and the other end at main box).   I also have a Power Suply box with out put of 12.3V DC and 5Amps.  I want to use Coax RG6 for Video transmission and CAT5 for Power transmission.  The distance to run cable from a surveillance camera to a main box is about 40feet - 50feet long.  I'm trying to use a CAT5 cable for 12V DC to run for my surveillance camera (12V DC 500mA), I use 2 pairs for positive (4 wires) & other 2 pairs (4 wires) for negative.  I wonder if I do this way, will it have any hazard at all?  Please advise! Any advice/help is appreciate! Best regards, DP

Question by dknp 9 years ago  |  last reply 2 months ago


Why Cordless Drill (Bosch 7,2volt) do not work using Laptop Adapter

Hello all.. I got problem with my cordless drill. It's battery is leak and i need to replace it using Laptop Adapter power suply. I have HP laptop adapter with Voltage Output 18,5Volt 3.8Amp. I just connected the + and - of laptop adapter to the cordless drill, BUT it do not want to turn and ONLY MOVE SEQUENCE (move-stop-move-stop-move-stop....). Its move is so strange for me, it's like pulse voltage because the drill just move for a moment then its stop, then its move and stop and always like that... I don't know is it DC or AC, and I've try to make circuit to make its voltage become DC using 4 diode and capasitor, But the result is same (move-stop-move-stop...). Then, I try to connecting the cable adapter to the drill and then pull off and connecting again with rapid sequence. Then the drill want to turn fastly... Please Help me, how to solve this, i need this adapter work for my cordless drill.... I've make a test to, I used AC dinamo (not DC dinamo motor) and connect it with the Laptop adapter, it's turn normally and fast... Please anyone here help me...

Topic by ddeeen 5 years ago  |  last reply 1 year ago


Simple question 230v to 12v 50w/5a timed output

Hi, know a lil about electronics and electrical just want to make sure i'm not being a dummy or if there are any other better alternatives. Problem: A timed output circuit has gone bang on an piece of work equipment, wont go into detail as it may confuse the situation but it all works apart form the timed lamp button, I can see components on the lamp circuit disintegrated etc... So I wish to make the lamp part sort of stand alone. plan is to convert a 230v suply down to 12v 5a as the lamp it needs to power is 50w. Resolution: I was going to get this https://www.amazon.co.uk/200-250V-Halogen-Light-Electronic-Transformer/dp/B00CXK30UW and http://www.ebay.co.uk/itm/DC-5V-12V-24V-Infinite-Loop-Cycle-Timing-Timer-Time-Delay-Relay-ON-OFF-Module-/192106941494 Build accordingly and place in a project box with a push button on the project box also. Can anyone see any issues with this? Or am I complicating it, maybe the transformer then this? http://www.ebay.co.uk/itm/CAR-TIMER-SWITCH-TIME-RELAY-DELAY-OFF-CAR-LIGHTS-UNIVERSAL-KIT-1-105s-10A-12V/271203168131?var=570157183343&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D46150%26meid%3D5e8c43f27aec4c1092baed675673ef1f%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D280890951562&_trksid=p2047675.c100005.m1851 or http://www.12voltplanet.co.uk/12v-universal-interior-light-delay-timer-relay-10-sec-delay.html any alternatives? advice?

Topic by TerryJ31 1 year ago  |  last reply 1 year ago