Powering my project

I have a project I'm needing to power: - 12V for LED light strip and servo - 5V for DHT11 and fingerprint sensor - 3V for a radio module

I've purchased a bi-direction voltage translator from 5V to 3.3V, so I think I'm good with the radio. However, what is the best way to deal with the 12V and 5V power supply design?

I have a nice 12V power supply and was looking at these types of power supplies: 1) http://www.ebay.com/itm/MB102-Breadboard-Power-Supply-Module-3-3V-5V-F-Solderless-Arduino-mini-usb-/321557647999 - or - 2) http://www.ebay.com/itm/MB102-Breadboard-Power-Supply-Module-3-3V-5V-For-Arduino-Board-/171044190923

I could tap off of the 12V before it goes to this module and end up getting options for 3.3V and 5V for anything in the future. Since I may also shift over to a 3.3V Aduino, I may need a 5V power supply anyway.

Question I have is: 1) do a voltage divider 2) purchase a power supply like this or another you recommend 3) something else I haven't called out here.

Thank you!

I've purchased a bi-direction voltage translator from 5V to 3.3V, so I think I'm good with the radio.

That is for signals NOT for power.

1) do a voltage divider

No a voltage divider is for signals ONLY, not for powering things.

3) something else I haven't called out here.

Use the 12V power supply and get a 5V regulator and a 3V3 regulator to derive the voltages from the 12V. These can be either simple linear regulators or the more energy efficient switching buck regulators.

What arduino device are you using? What voltage is it running at?

The biggest challenge, I think, is going to be the fact that the radio wants only 3, but you're trying to interface it with a presumably 5 volt device.

Interfacing the DHT with lower voltage device is no problem - it's open drain output.

But the radio probably isn't, so you'll need the level shifter for that (though you'll still need a 3.3v supply.

You are linking to solderless breadboard supplies - is that because you're building this on solderless breadboards (those are really flaky, you know)?

Honestly, I'd do.... DC-DC stepdown converter from 12v to 3.3v ( http://www.ebay.com/sch/i.html?_nkw=dc-dc+step+down+converter ) to get you the 3.3v, and run the Arduino board (I assume a pro mini, or nano?) run off 3.3v. (this is a switch regulator - you can find step up ones on ebay too. Lots of styles to choose from for mindbogglingly low prices)

Then, I'd use a 7805 or other linear regulator to get me the 5v for the DHT (don't forget input/output caps) - the DHT uses barely any current, and 7805's are dirt cheap (one of the few genuinely useful parts that you routinely find when taking crap apart that's easy to remove, too)

Outstanding advice. Thank you and this helps me a great deal.

Again, so much to learn for these darn computer science guys like me stepping into the EE realm.

I had another post where I was asking advice under this thread that tells you what I'm trying to do. YouTube video link is in my last post. Here

To your questions/statements:

Use the 12V power supply and get a 5V regulator and a 3V3 regulator to derive the voltages from the 12V. These can be either simple linear regulators or the more energy efficient switching buck regulators.

I have been reading about heat output using regulators and that concerned me. If you don't think that's an issue, then I'll do that.

What arduino device are you using? What voltage is it running at?

I'm using the Nano v3 right now at 5V, which is at the heart of why I'm investigating switching to a 3.3V version. I ordered some, but that boat from China takes a while. I am using either WiFi modules or RFM69HWs on most of the things I'm building. I have a stock of like 10 Nano v3s I'd love to use still.

You are linking to solderless breadboard supplies - is that because you're building this on solderless breadboards (those are really flaky, you know)?

Only for my protyping, but I was thinking of soldering into one of the units I mentioned on final board, which seemed whacky. That was part of the reason why I put this out there for some education.

Between what both of you mentioned, I can see applications for both and I think I'm going to buy the materials for both methods. I have a bunch of old electronic stuff in the garage, so I'll look for some of those 7805s.

Thank you!

You can get UBECs like below to provide 6v for the servo and 5v for the 5v devices. Bottom are the breadboard power supplies for the low power components.

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_BIN=1&_nkw=UBEC&_sop=15

http://www.ebay.com/itm/MB102-Breadboard-Power-Supply-Module-3-3V-5V-For-Solderless-Breadboard-1-piece-/181682411193?hash=item2a4d1d96b9