Dual Rail Supply - Different Options for Negative Voltage

🔥How to get for example +12 and -12V. Dedicated ICs, dual rail supply with center tapped transformer and much more. Learn how to get negaive voltage.

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00:00 Intro
02:09
04:49
06:00
07:50
08:35
10:01 Thank You

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#electronics
#homemade
#circuits

[RoidDroidVoid]

The most clear explanation that I've ever heard for the use cases and ways to achieve negative voltage. Awesome channel!

[szymonjastrzebski]

Batteries don't give "Positive DC voltage", they're free of any kind of reference and they can be used in circuits to provide negative voltage reference

[ddub]

As always, great video!
Since the last example is capable of delivering more current using the transformer, you could take it a step further and use variable regulators with some current bypass transistors (TO-3 style) for a big current variable power supply. That would be great for the bench! Keep up the good work. These videos are appreciated.

[timthompson]

Great video. I would recommend an input fuse in that last center-tapped transformer example. I know that’s not the focus of your video, but a fuse is immensely important, so it is good to get people thinking about that aspect of circuit design right from the start. Also a good rule is to use an isolation transformer of some sort when working with mains voltage.

[aaronwunderlich]

Just noting that it is less common (especially in audio applications) to regulate the rails of the supply. Yes the rails will sag under load, it’s just critical that your max load will not allow clipping into the rails. This headspace will ensure clean outputs. This same approach goes for both power path to speakers as well as signal attenuation. The regulation circuitry can inject noise, so less is more. Great video!

[kdog]

Interesting video with some great examples! On thing I noticed is that in the first example, you have your polarized capacitor reversed since the gnd ref is lower voltage than the high rail so it should be flipped.

[amdadulhaque]

Lately I have been doing a lot of research online about dual rail supply for my DIY function generator output, in the meantime this guy came up with the exact same thing, quite a coincidence.😅

[cmuller]

5:35 This push pull is far from ideal because there's a 2*0.6v dead zone. The output of the AO cannot change instantaneously so if the requirements if the virtual ground change from source to sink the transistors won't react immediately. A simple solution to improve the situation is to add a resistor between the AO and the output. For low loads (actually low differences in loads for + and - supplies) it's the AO that directly provide the current through the resistor.
Another solution is to have an AB amplifier but that's more complicated.

[CLARVO]

Cool, I never understood the use of negative voltage till now but after seeing your video I understood it clearly and understood how to achive it... Keep It Up ☺️

[treelibrarian]

Nice simply explained video... just want to add a couple more options for higher power applications: since boost and buck converter modules handling currents of 10 to 50 amps are commonly available, if one has a useful supply voltage already (can use a boost or other supply to get this first) one can either use a boost converter to generate a voltage further above that and use the middle of the three voltages as ground (current can flow from the top to the middle happily if the middle voltage is where the boost that is generating the top is supplied from) or using a buck module, connect the power input across from +in to +out, and a negative voltage set by the output Vset pot will be generated at the common ground (this works with most buck converters and should work with all, but I have found some which don't). This can easily generate larger -ve voltages than the +ve supply, and be paired with a boost regulator to get a balanced +- for something like an IRS2092 class-D amp module.

[strayangel]

These would be great for running mosfet's which require a negative sometimes. Thank you for the video this is awesome.

[anonym]

Interesting video with a lot of great solutions. Another option I have recently seen used is to use two isolated DC DC converters and then creating a virtual ground between them. This gives a reasonably stable output voltage, while still allowing for multiple amps of current draw. The only downside is that the isolated DC DC converters can be kind of expensive, especially the ones with higher current ratings.

[TTVEaGMXde]

For audio with sufficiently large capacitors, the op amp to ground only has to compensate for the differential current. So only the current that results from the op amp offset voltage or DC servo compensation. The OPA 1677 Fet Op Amp (overload-proof for start) can be enough.

[rodolfoacostacastro]

tip here: you could get a 12v AC power supply online. AC not DC, so you will have the transformer already encapsulated in plastic and safe to use with the main outlet. Now just add the rectifier and regulators from the circuit (12:15 in video). This is a common trick to get a cheap power supply for analog synths :)

[tylerufen]

most useful! thank you so much! i've been looking for a comprehensive video on negative voltage sources for so long! thank you very much, very appreciated from me! 👏💯👍

[korishan]

Curious why you didn't cover High Frequency transformers for the split. You mentioned about using the Mains to power the transformer, but what about using a bank of FETs to create high freq?

[famitory]

you can use two positive linear regulators set up as two off the same value power supply stacked on top of eachother (so that one's positive is the other's ground) but you have to be careful about what's connected to the screw tab, since now one of your heatsinks will be at 0v and the other will be at your negative supply voltage.

[a-zudt]

Thank you! Soldered it with different transistors. Is working.

[saberxebeck]

Not sure if you know them but I would be really interested in the efficiency rating of those of those power supply's too.

[XCang]

I've built a credit card-sized dual power supply using two TPS5430 DC-DC converter chips last year, taking a single 15V power supply. For ±12V output voltage it could provide 2.5A current for the positive rail and 1.5A for the negative, while the no-load ripple is 4mVpp and 6mVpp, respectively. Not too shabby for powering a couple of op-amps considering the low current consumption, but would be a good idea to further suppress the ripple using a pair of LDOs.