I need 5v, 12v, and -12v in my circuit. What would be the best way to get this from a 12v, 5A supply?
For 5v, I could use a regulator. Not too sure about -12v.
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\$\begingroup\$ How much current do you need at -12 volts? That will decide what type of regulator to use. \$\endgroup\$– user105652Commented Jun 22, 2018 at 0:51
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\$\begingroup\$ I don't know exactly, but it will only be used to supply an op-amp, and a 10v signal (~40ma). \$\endgroup\$– 19172281Commented Jun 22, 2018 at 0:57
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\$\begingroup\$ Switched capacitor ICs can achieve your current requirements, I think, and are pretty simple. That could get you \$ -12\:\text{V}\$ from your \$ +12\:\text{V}\$ rail. These are found both with and without a follow-on regulator. You don't need the follow-on, so look for simpler ones. Use "switched capacitor voltage converter" or something like that in a search. \$\endgroup\$– jonkCommented Jun 22, 2018 at 1:13
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4 Answers
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To get all the voltages you need from just a 5 V USB or an adapter, I would use this board
Input: 5 to 24 V DC
Output: + 12 V, -12 V, + 5 V, - 5 V, +3.3 V maximum output current: 300 mA per channel
You can buy these are a DIY kit or soldered and ready to use.
The design is based on a Cuk converter.
I have one and it does the job. Much safe than an ATX supply as it cannot deliver so much current that wires will melt. It's short-circuit proof.
answered Jun 22, 2018 at 7:16
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\$\begingroup\$ The problem is, I don't think 300mA is going to be enough for the 5v channel. \$\endgroup\$– 19172281Commented Jun 22, 2018 at 11:55
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\$\begingroup\$ That's extremely easily solved by using an additional switched regulator module, for example: ebay.com/itm/… It can deliver 3 A at 5 V, is that enough? Yes you can connect both boards at the same time to your 12 V supply. \$\endgroup\$ Commented Jun 22, 2018 at 13:13
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\$\begingroup\$ Could you please link me to one which is pre-soldered, and not on ebay? :) \$\endgroup\$– 19172281Commented Jul 26, 2018 at 16:15
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\$\begingroup\$ Also, I notice that each supply has it's own GND terminal. Is that to say that they do not share a GND? For example, could I ground all elements in my circuit to the same GND terminal? \$\endgroup\$– 19172281Commented Jul 26, 2018 at 16:16
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\$\begingroup\$ @B4039 All grounds are connected together, if this board had electrically separate grounds then it would be much more complex and expensive. You will have to figure out yourself where you can order a ready-made one. \$\endgroup\$ Commented Jul 26, 2018 at 21:14
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THe easiest way to deal with this is to get a used ATX PC power supply. They output everything that you need. Just ground the PSON wire.
answered Jun 22, 2018 at 1:22
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\$\begingroup\$ Although this will work, I would not recommend to use an ATX supply as these can deliver very high currents. Make the wrong connection and your wires and components are fried :-( \$\endgroup\$ Commented Jun 22, 2018 at 7:17
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Check out 78XX series DC to DC regulators, they are drop in linear compatible and you can generate negative voltages as shown below:
answered Jun 22, 2018 at 3:02
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I've used this type of circuit to generate -12 volts from a positive supply: -
Add a 79L05 to produce - 5 volts and your done. If you decided you need higher power then consider this: -
This Q&A has a couple of other options.
