G120 TH module's power supply

This module seems to be very nice and very flexible to attach my own circuit board controller.

Only problem is that it is lacking power supply for 3.3V and 5.0 V.

I would not like to spend time to design good P.S. to board.

My question is whether is there a good module available that can provide a good power source
(like integrated in FEZ Cobra III) for 3.3V and 5.0 V?

  • Jari

Please see this https://www.ghielectronics.com/community/forum/topic?id=23832&page=2#msg221459

Hi Gus,

thank you answering.

But the link goes to: “Tech Talk with Gus 02 - 0.96” 128x64 OLED display"
and I did not see any reference to power supply.

However that OLED interfacing is really interesting and presentation was very nice.

  • Jari

Sorry, here


I’m using a LM3761 switchregulator to power my Board and the G120 on it. There’s a breakout-module (e.g. from adafruit LM3671 3.3V Buck Converter Breakout - 3.3V Output 600mA Max : ID 2745 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits) available, but it’s also very easy to integrate onto your board.

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Hi gix,

indeed that LM3761 buck DC/DC converter seems to be quite optimal solution. As far I can see all needed components are included.

The input side of LM3761 Buck can tolerate 3.5 to 5.5V, so do you have a battery or similar to supply it?

I noticed that very same company do have also a product “VERTER 5V USB Buck Boost”. This input is 3-12VDC and output 5V DC.

Perhaps using these two connected in series, there is a similar solution to have both 5V and 3.3V on board than FEZ Cobra III power supply design has…

  • jari

My board is powered via USB, so the 5V are ok for me. I first looked at the LM2734 (http://www.ti.com/lit/ds/symlink/lm2734.pdf), that has a wider input-range (up to 20V) and an adjustable output but needs a few more external components. But since the 5V were ok for me, I chose the ML3671, that was easier to use for me. It needs very littly space (don’t mind the board-layout, it’s the first one I designed :-[ )…

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@ glx - where is the full image? :snooty: :slight_smile:

Here is it ;)…
It’s the controller-board of a text-clock I made :). But it can only “speak” german until now ;).

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@ glx - can I tweet/facebook this?

Of course you can :). It’s nothing commercial, just a non-profit-project, maybe I’ll share the hardware and the code when it’s a bit more showable (the software is a bit ugly by now) ;).
Here’s another pic from the backside :).

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Done, thanks.

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I just posted in the ‘General Discussion’-board, so you maybe can link to that, since this one has actually anothe topic ;)…


Hi glx & Gus,

that is really nice project and basically I am also trying to do same. I have Fez Cobra III and WiFi module. Now they are wired to each others, but the plan is to have a mother board containing G120TH + external WiFi module.

  • jari

back to power supply options,

there are a plethora of cheap suitable power supply modules depending on what you want to do. You mentioned batteries, so a switching regulator will be useful - can you confirm what you need?

It’s also a TH module you’re referring to so there’s some benefit in looking at breadboard modules, like Gus had on the video… here’s an example of a search in eBay looking for “power supply breadboard”, http://www.ebay.com.au/itm/MB102-Power-Supply-Module-3-3V-5V-For-Arduino-Solderless-Breadboard-Brand-New-/282026696421?hash=item41aa19dee5:g:6UYAAOSwrXdXKa8a that you can run from multiple sources and get 3v3 and 5v out - it uses cheap linear regulators though so it’s more a wall powered device than a battery powered one.

Then there’s something that would be a little more useful to provide 5v out, and you have a LDO for 3v3…
http://www.ebay.com.au/itm/NEW-High-Quality-1-23-30V-LM2596-DC-DC-Power-Buck-Step-down-Module-12V-To-5V-/191837567139?hash=item2caa68f8a3:g:dJAAAOSwwpdW-jZo are cheap and plentiful (I bought a pack of 10 of them at one stage and still have them scattered across the bench and in projects). They’re adjustable and handle higher input voltages so are great for batteries (I have one on a solar powered netmf device in the garden)

Hi Brett,

what I am looking for solar panel or a battery to have input to power supply unit. In that sense switching regulating power supply would be better solution as you stated.

This one could be adjusted to output 5V:

You wrote: “and you have a LDO for 3v3”. Do you mean that I could buy additional component take care from 5V to 3.3V ?

Then I would have both 5V and 3.3V as my original goal was and what G120 TH can handle.

  • jari

One more thing regarding this:

MB102 Power Supply Module 3.3V/5V For Arduino Solderless Breadboard Brand New:

In description it says: “Can be switched to 0V, 3.3V, 5V”.

This means, as far I can understand, that only one output voltage can be selected at time NOT both output 5V and 3.3V simultaneously?

do you need 5v for anything in the system? If not, then you should plan to adjust an adjustable regulator to 3v3 not 5v, as the module requires 3v3. Optionally, if you need to have 5v power for some other part of the system, then you will need to have two regulators of some kind. If you need 3v3 and 5v then you could get a adjustable regulator and use a very simple LM1117(3.3) to take the 5v output from the regulator and power the 3v3 circuit including the G120 (yes, that’s going to require more hardware). Another option of course is to use two adjustable regulators, one set for 5v and one 3v3, both running off your solar/battery combo.

Can I ask, have you thought about power management and the demands of all the things in your system, and specified the size of battery and solar panel accordingly?

Edit: forgot to answer the question about the MB102 power supply module. That uses LM1117-type low drop out (LDO) linear regulators, so is less efficient than a switcher. It has two power rails, one can be set as 3v3 and one as 5v, giving you both power options (if you need them).

I wouldn’t use these cheap LM1117-regulators in a powersupply, especially in a battery/solar-usecase, because they waste a lot of energy and can get pretty hot. If you anyway plan to design a board, I would integrate a switch-regulator on it. If you go down to 3V from 12V even with only 100mA flowing, there is about 1W (0.9W) wasted with a LM1117, with 1A it will probably burn your house down :smiley: with 9W of heat on that small package…

Well, I have not done any major calculation or plan about power management. I am thinking now that it would be good to have both voltages available and that way make application range as wide as possible.

That crossed also my mind that if 5V not needed then one Buck can be adjusted 3.3V to get board running.

Brett, there are really good ideas at you answers and I believe that I can manage now. I actually ordered from eBay both types of power supplies discussed in this post chain to test them. (Price is not too bad, so I can do that).

  • jari
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