Single rail supply to +/-6v supply options - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: March 30, 2024, 12:46:54 pm
content: I'd like to power my circuit (schematic attached) with a DC plug in adaptor. The circuit needs a +6v and -6v DC supply. I have NOT prototyped the circuit yet, so I have yet to determine how much current is required. I'm assuming less than 1 Amp.I have thought of the following options.1/ Applying 12v or lower to a DC to DC boost convertor (12v output) and then feeding the output to a rail splitter circuit that uses an op-Amp and produces a virtual ground. I'm not sure how this circuit would handle possible uneven current flows in the + and - rails.2/ Try to redesign the whole circuit to work from +/-5V and then using a TPS65133 circuit (datasheet attached) to power it. How easy/difficult would it be to change the circuit to work with +/-5v instead of the present +/-6v supply?3/ Using an LM317/LM337 based circuit (not sure if this will work with a single voltage input). I've never built a dual rail supply using these linear regulators. I'm assuming that they would need higher than 12v input, as they are quite wasteful. Are there any newer regulators that can do the same thing and better?4/ Something else I haven't thought of yet. Hence, this post.Can anyone give me some more food for thought? Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2024, 12:56:32 pm
content: Don't bother. Use a single 12V power supply.The second PDF "PortusHaywoodForQSPICE.pdf" shows how to use a 6.2V zener diode and resistor to get a split power supply. Look at the schematic, on the bottom right hand side of the page.https://www.eevblog.com/forum/projects/single-rail-supply-to-6v-supply-options/?action=dlattach;attach=2089586

author: tooki
author_rank: Super Contributor
timestamp: March 30, 2024, 12:58:52 pm
content: Quote from: djsb on March 30, 2024, 12:46:54 pmWhat about doing one of the several options shown right in the schematics you posted?!They show a supply using a +12V regulator and a rail splitter. But the text expressly says you can use -6V and +6V, or +6V and +12V. The latter is trivial to generate.

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2024, 03:40:13 pm
content: I had a quick look at the schematic and marked up where the +12V and 0V, or ++V and-6V, should go. I then noticed it says link to B or C. the question is which? It will also short circuit a 470R resistor, if connected to C, which I've also highlighted, so perhaps that resistor can be removed?

author: djsb
author_rank: Super Contributor
timestamp: March 30, 2024, 05:38:31 pm
content: Has anyone got the schematic for the circuit that uses a 741 opamp as a buffer and a couple of bipolar transistors in push/pull configuration. I had a look on YouTube and I can't find it anywhere. I want to do a simulation in Kicad so something that uses common parts makes this easier.Regarding the power supply in the schematic I attached, I will try a 6.2v Zener as shown as a last resort. I just want to use something that has better regulation (I don't get along with Zener diodes). There are a few switch mode type regulators from TI but they tend to be a bit noisy.I want something with as low a noise as possible, as this is an audio circuit.Thanks.PS Found this but not sure if it's correcthttps://www.eleccircuit.com/power-supply-splitter-circuit-using-op-amp/

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2024, 06:24:26 pm
content: Why? The zener diode + resistor configuration is more than sufficient. I even put colour coding on the schematic to show how it's connected!