I’m aiming to power an Arduino project with the 12v battery that’s in my van. Space is limited so I’m using a “standalone” Arduino that I’m making by following this tutorial. Instead of using a linear regulator, I want to use a switching regulator (a buck converter?) as it’s going to be on pretty much all the time in the van and I believe linear regulators just waste the excess power to get the 5v? Most of the converters that I’ve seen are 12v to 5v, but when the engine is running, the supply will be more like 14v. Can anyone point me in the direction of a small (and preferably cheap) switching regulator that would take the 14-15v and give me a steady 5v? I’ve spent some time looking around but I’m not sure what I’m looking for to be honest!
A bit more info on the project, in case I’ve missed out details which make a difference It’s very basic. Just a DS18B20 temp sensor reading outside temperature, which the Arduino then displays on a small OLED screen mounted to the dash of the van. It states the current temperature as well as the min and max since it was last reset (just for curiosity for when I’m camping in it). There are two buttons, one to change the display from current to min/max, and one to reset the min/max temps.
I'm a little bit in love with these at the moment. They will fit into a TO-220 footprint and take a huge input voltage range with no need for external components other than the typical input/output smoothing caps (which should technically be used on a linear regulator as well anyway).
They look great, thanks! I've just read the spec document for these and it says that they do not require external capacitors as they have internal built in ones. Does this refer to the input/output capacitors, or is that something totally different?
I've just stumbled across these converters which use a potentiometer to give an adjustable output. They're a bargain at £1.88 delivered! Would they be suitable? Could you just set it to 5v and then glue the potentiometer in position?
cuffbertt:
I’m aiming to power an Arduino project with the 12v battery that’s in my van. Space is limited
[...]
anyone point me in the direction of a small (and preferably cheap) switching regulator that would take the 14-15v and give me a steady 5v?
I'm in a similar boat (OK, "car") with a project of mine. I've looked around and the best solution I've found is the Pololu 5V 0.5A switching regulator - plugged directly into your Arduino's 5V pin (not VIN). Small, inexpensive, and only require one small, external ceramic cap (still cheaper and smaller this way than other solutions).
Of note: While your vehicle appears to produce about 14V when on, there are significant issues with managing power in any automotive environment. (I'm in the process of revamping the solutions presented there to use a power management chip and n-channel MOSFETS instead of the discreet/p-channels that are there currently.)
cuffbertt:
I've just stumbled across these converters which use a potentiometer to give an adjustable output. They're a bargain at £1.88 delivered! Would they be suitable? Could you just set it to 5v and then glue the potentiometer in position?
I've tinkered with these - and others of their ilk. In my experience, their outputs tend to "wander" a bit much (yes, even glued). Certainly a bargain (and I think you'll be able to find even cheaper, smaller ones), but this is a case of "you get what you pay for".
Though, maybe if you set their output a bit higher (6-6.5V) and use them on the VIN pin...
dephwyggl:
I'm in a similar boat (OK, "car") with a project of mine. I've looked around and the best solution I've found is the Pololu 5V 0.5A switching regulator - plugged directly into your Arduino's 5V pin (not VIN). Small, inexpensive, and only require one small, external ceramic cap (still cheaper and smaller this way than other solutions).
Of note: While your vehicle appears to produce about 14V when on, there are significant issues with managing power in any automotive environment. (I'm in the process of revamping the solutions presented there to use a power management chip and n-channel MOSFETS instead of the discreet/p-channels that are there currently.)
Cheers!
Dirk
Ahh, that's just what I'm after, thanks! I've found some 0.3A versions of them which were a bit cheaper at £3, so I've ordered a couple of them. From my limited understanding I think my current requirement is going to be quite low, so they should be perfect.
I've read the spec for the converters and can't find anything about the capacitor. Do I add them in the same way that I would for a linear regulator? So 10uF caps between Vin & GND and Vout & GND?
cuffbertt:
Ahh, that's just what I'm after, thanks! I've found some 0.3A versions of them which were a bit cheaper at £3, so I've ordered a couple of them. From my limited understanding I think my current requirement is going to be quite low, so they should be perfect.
Yep. If all you're powering is the Arduino, 300mA should be plenty.
cuffbertt:
I've read the spec for the converters and can't find anything about the capacitor. Do I add them in the same way that I would for a linear regulator? So 10uF caps between Vin & GND and Vout & GND?
See the "LC voltage spikes" note at the very bottom of that page: One 50V, 33uF or larger electrolytic between VIN and GND.
As per my other comments about automotive power, I'd suggest - at minimum - something like:
Hi,
Did you look into use a 12v to USB adapter for car. I used one for my cell phone. Today cars have a USB adapter or if you car it is too old you can get one that plug into the lighter. They change +12 to regulated 5Volts.
Hi,
Did you look into the use of a 12v to USB adapter for car. I used one for my cell phone. Today cars have a USB adapter or if you car it is too old you can get one that plug into the lighter. They change +12 to regulated 5 Volts.
cuffbertt:
I've just stumbled across these converters which use a potentiometer to give an adjustable output. They're a bargain at £1.88 delivered! Would they be suitable? Could you just set it to 5v and then glue the potentiometer in position?
Stumble further, they are antiques. You get MP1584 for almost the same price, they have a much higher switching freq and are thus much smaller. Consider exchanging the pot with fixed 1206 resistors. Stacked 47+470Ohm over middle and outer contact will give you close to 5V.
Google "Simple Switcher". They are devices made by Texas Instruments and as the title suggests they are very easy to use. If you go to the TI website, you will discover that TI's web application will do all the hard work for you in terms of calculations and what components you will require.
It’s very basic. Just a DS18B20 temp sensor reading outside temperature, which the Arduino then displays on a small OLED screen mounted to the dash of the van. It states the current temperature as well as the min and max since it was last reset (just for curiosity for when I’m camping in it). There are two buttons, one to change the display from current to min/max, and one to reset the min/max temps.