a simple little circuit that will help anyone really new to electronics. you'll see a lot of circuits that have ICs that require a split power source IE +5 volts and -5 volts, there are quite a few ways of achieving this, ranging from the full on voltage regulator method (so you have a LM317 and a LM337 with a center tap transformer) to charge pumps or you can use a voltage divider or in the case I have laid out, a voltage divider with a unity gain buffer to give you a virtual ground. basically the circuit splits the input voltage in 2 and makes a center reference point between the 2 voltages - that's the really stupid way of explaining it anyway.
for the sake of better performance (especially for you audioweirdos) I have included capacitors on the input however usually I wouldn't bother including them because I put filter caps on the main power supply but I put them on the layout for the sake of completeness.
it maybe worth noting that if you saw my headphone amplifier circuit earlier on, I used a different type of voltage divider, quite similar to this without the op-amp buffer but instead of giving me dual voltage supply, that one gives me a Vref of half the Vin.
anyway here is the circuit
I saw your circuit and I am trying to get a dual polarity power supply from a single 5V dc supply. But what your circuit really does is to split the voltage rather than give the positive and negative polarity so that I can feed dual polarity voltage on to the op-amp. What can be the solution for that? Please help.
ReplyDeletewell if you put 5 volts into this you would have +2.5v and -2.5v referenced from the virtual GND
Deletethis is a very common way of powering dual polarity circuits - in fact it is probably the most common way.
I suggest you breadboard this circuit if you don't believe me.
Actually I already tried it on breadboard. I wanted to use it to give dual power to an op-amp LM392. However, I am not sure how to give it through this circuit because when i measured +vout and GND from multimeter it gave +2.5 V and similarly when i measure -vout and gnd it also gave +2.5 V.
ReplyDeleteyou've done something wrong - try looking at the polarity of the capacitors for example. double check
Deleteswitch the positive and negative, the ground should be at the virtual ground and the "positive" should be at the negative output
Deletehonestly dude, I've used this circuit hundreds if not thousands of times - if it's not working how I have described then the problem is at your end. it is all labelled how it should be.
Deletehere is a picture of it http://4.bp.blogspot.com/-iyTMhUkew4I/UYRUGo5wh2I/AAAAAAAAAkI/UXL1vOieb5M/s1600/P5044875.jpg
Great lttile circuit, works a treat ... thanks :)
ReplyDeletecheers dude. I'm not exactly sure how the dude above is having difficulty with it (or was having difficulty)
DeleteHello, I would like to ask you very kindly why when I'm connecting the corresponding resistors to obtain a suitable gain for the op-amp, so the bipolar source is not anymore symmetric. In my case is giving more negative voltage than positive. Could you give me some advice please? . I'm trying to make ac active low pass filter and I don't know what I'm doing wrong.
ReplyDeleteThank you in advance for your help my friend.
Best regards
Steve
it depends how much it is out by. but the usual reason is because the resistors aren't exactly matched.
ReplyDeleteessentially this is a voltage divider so if the resistors are exactly 100k you will get an evenly divided voltage however if one resistor is out by even a little bit it can make a big difference. so measure the 2 resistors before you put them in the circuit.
they don't have to be exactly 100k but they have to be exactly the same as each other
Hey,
ReplyDeleteThanks for sharing this neat circuit. Can you tell me how many amps can it handle? I am planning on using it to power 6x TL072 op-amps.
Alex
I'm not sure - you'd have to try it out. personally I would use 3 TL074s or even the TLC074s and dispense with the dual supply altogether (FYI there is a TLC072 also)
DeleteI can't really change the op-amps right now, as I already made the PCB's for my project, everything is soldered together, and remaking everything would take me just to much time. I measured the current consumption, and the results I got was 20mA per rail, so that means 40mA per total, I guess, that's a little to much for a circuit like that? What do you think?
DeleteWould this work for +/-12? Looking for something to power a Eurorack circuit...
ReplyDelete