5VDC Boost Converter
erco
Posts: 20,256
My latest little robot runs off a single Li-Ion cell, which is 3.7-4.1V, depending on the charge. The BS2E and sensors need 5V, so I used one of these Ebay DC boosters (~$2 or less) to generate the 5V for the electronics. Two 9g servos and the DC drive motor are powered directly from the Li-Ion. Works like a charm and it's quite convenient to use just one battery. I'll be buying a few more of these boosters.
Face it, even the 3.3V users among you need 5V for sensors every now and then!
http://www.ebay.com/itm/1PCS-DC-DC-Converter-Step-Up-Boost-Module-1-5V-to-5V-500mA-USB-Charger-for-MP3-M-/400548234433?pt=LH_DefaultDomain_0&hash=item5d428904c1
Face it, even the 3.3V users among you need 5V for sensors every now and then!
http://www.ebay.com/itm/1PCS-DC-DC-Converter-Step-Up-Boost-Module-1-5V-to-5V-500mA-USB-Charger-for-MP3-M-/400548234433?pt=LH_DefaultDomain_0&hash=item5d428904c1
Comments
I found two for $3.14 here.
And yes, 5V is often needed even when using the Prop. I think I'll get a few of these.
The one I used is also one I bought a while back, and it's slightly different from these newer units. Mine have a square trimpot on board to set the output voltage. It was very close to 5.0V as delivered. I have another one, which I am now tempted to test to see what the output voltage range is. BTW, I have not tested any input voltage besides a Li-Ion battery.
Hmmm, if the output voltage goes down to 4.2V, I could charge one Li-Ion from the other, then back and forth until the power efficiency goes down to zero. Nonetheless...
LOL!
I was uncommonly lucky to have power efficiency reach zero in just one conversion.
EDIT: I took a careful look at my boards and compared them against the illustration on the page you linked in your first post. The units appear absolutely identical to that one, including component markings.
BTW, the most annoying behavior exhibited by the unit I tested was that it put nearly a direct short across the NiMH input cell. While it didn't completely ruin the cell, the overheating did it no good. And this was with a very modest resistive load on the output of the board. I stuffed the whole thing away in disgust... Most cheap Chinese electronics seem to work great. This was a notable exception.
http://www.ebay.com/itm/1PC-0-9-5V-To-5V-600mA-USB-Charger-DC-DC-Converter-Step-Up-Module-New-/200953466361?pt=LH_DefaultDomain_0&hash=item2ec9c28df9
@
Great find! I'm going to snag a few.
Meanwhile, repeating erco's test, my first board was still messed up. But the second board worked well. Without an external load it drew 7 mA and its output measured 5.04V. This dropped to 4.95V with a 25mA load. On the input side, the current went from 7 mA to about 150 mA with the load applied. This is a 70% conversion efficiency - not bad for a simple and cheap boost converter operating with a light load.
I presume that the first unit out of the bag was simply a lemon or else got static-zapped somewhere along the way. Gotta say that my attitude about the product has rebounded dramatically.
So are they using altered photos?
The $1.25 looks like it uses a different connector than the units I linked to earlier.
The USB connector in the top photo looks much too thin. They're not trying to make there boards look thinner than they are, are they? I'm betting the photo just got squished when they resized it.
Thanks for the find Amanda.
And probably use the exact same components, just with a slightly different layout.
The second one is slightly cheaper, though.
You heard it here first... Great find, Amanda, thanks for your diligence and competitive spirit! I'm sure you and I will update this thread as prices fall towards the dollar level.
@Duane: is that a USB slot, or an SD card holder in that photo?
I wondered about the look of the connector in the listing, but it looks like it just got mangled in uploading. Seems to be a USB "A" connector.
@
Follow up question: Which is an indicator of higher conversion efficiency, black smoke or white smoke?
So I peeked in to see if they had something similar in stock. Not exactly. I got a 2 amp device that will accept 3-35V inputs and output between 1.25v and 30v regulated.. Cost $9USD ($270NT).
Yes, more expensive... but much more capacity. I guess with the right solar panels, these would keep a battery pack fully charged.
This? That's a buck regulator, not boost like the rest of the thread is discussing.
and a 15W step up converter for $5.12: http://www.ebay.com/itm/LM2577-3-30V-to-4-35V-DC-DC-Boost-Converter-Step-Up-Voltage-Adjustable-Module/170929162919?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D713936326147691023%26pid%3D100011%26prg%3D1005%26rk%3D2%26rkt%3D5%26sd%3D141038563279%26
It really was just a fishing expedition and I can use this in an ordinary fashion, if I must.
@Erco... similar, but no current regulation, only one pot for setting output voltage. If looks more like the photo of the stepup converter, but I honestly need to do a bit of Chinese translation to be sure.
The chip is an LM2677s .. will read the data.
And of course you see the "Does not ship to Taiwan" on the $5.17 USD item. I have given up EBay entirely.
All the info was in Chinese, I just peeked at the input and output voltages. I was trying to buy something that would boost... the sales people run and hide from foreigners. It seems I have to shop with a list of good LMxxx numbers.
Fun to browse that Ebay store. Same seller as the AVR board kit I strong-armed many of you into buying
This tiny (0.35″
$10.50 w/LED readout 5-35V out http://www.ebay.com/itm/DC-DC-3-35V-to-3-5-35V-Voltage-Step-Up-Boost-Converter-Module-w-Voltmeter-NEW-/221261767300?pt=LH_DefaultDomain_0&hash=item33843aa284
3 for $6.30 5-35V out http://www.ebay.com/itm/3P-DC-DC-Power-supply-Adjustable-voltage-Converter-Step-up-Module-Output-5V-35V-/141054974007?pt=LH_DefaultDomain_0&hash=item20d7881837
$25 0-3000V out http://www.ebay.com/itm/Spellman-MM3P1-5X2619-DC-DC-Converter-0-3000v-High-Voltage-Power-Supply-/300961173060?pt=BI_Security_Fire_Protection&hash=item4612af0e44
@erco -
Got the 3 for $6.30 Step Up modules. Powered 24 inch red or white 12V LED strips that Parallax is selling using 3 AAA batteries.
Pretty slick!
I use these on small bots to power 5V sensors from a single Li-ion cell (which powers the servos directly). Board size can be decreased by unsoldering the USB connector; you can then cut the board shorter too. I made a breadboard-friendly daughterboard by attaching a 3-pin male header. Very useful.
Thanks for the alert.
BTW, except for the first board I tested (post #4) and foolishly extrapolated across the entire genre, all have worked great. Still, having the MOSFET lock up on that first board has made me cautious. I always test new boards with a current-limited supply, now. No sense risking your precious LiPo or NiMH cell (and possibly your health) on that first power-up.