While it’s the easiest way to lay out a simple circuit for prototyping, breadboards are a pain. They are the ultimate kludge; they work well enough, but no one will ever say that a solderless breadboard is the most elegant solution.
[Mahesh] isn’t completely fixing the problems of solderless breadboards, but he has come up with a better way to supply power to breadboards. It’s a project called snapVCC, and it turns a 9 volt battery into a regulated 3.3 or 5 volt supply.
The idea behind snapVCC is simple enough; just add a circuit board to the top of a nine volt and add a voltage regulator. [Mahesh] is using an LM317 adjustable regulator, with a switch to change the output voltage from 3.3 to 5 volts. An LED indicates the output active, and another switch disconnects the battery from the circuit. Yes, it’s very simple and very useful, confounding everyone who is wondering why this project didn’t already exist.
Hmmm – Why didn’t we think of this decades ago? Great idea!!
“To be simple is to be great” – Ralph Waldo Emerson
They did exist years ago, they don’t exist much these days because 9v batteries suck. We all use lithium (with boost converters) or USB these days.
9v batteries have always sucked, and I’ll be glad to see the end of them.
Here’s a DIY one from a few years back: http://www.instructables.com/id/Portable-5V-Regulator/
On a related note, joule thief LED torches you clip onto ‘dead’ 9v batteries still seem to be common. (They’ve been around for years as well.)
Not only their capacity sucks, but they are also the most expensive batteries. When I go to Walmart, I can get 48 AA batteries at the same price as a pack of four 9V batteries.
A properly designed boost converter (i.e not a crappy joule thief) that works from 2AA would be the most sensible option.
you have to admit though, buying a 2 pack of 9 volts is tons cheaper than buying six 2 packs of AAAA at $5 a pop.
I’ll admit I fell you’re shopping in the wrong spot. Even RadioShack has better prices than that.
(I can get a dozen AA for $5, and 30 for $10)
He’s talking about AAAAs.
Ah, so he is. Never mind then.
(They’re not really AAAA cells inside 9v batteries, btw)
(Close enough, I guess)
(Unless they’re the block ones)
Close enough is right. They’re different from AAAAs in the same sort of way solder tab NiMH cells are different from their replaceable versions. But it’s worth tearing apart a 9V considering how unpopular and expensive “proper” AAAAs are.
I have yet to ever have needed an AAAA battery, and doubt I ever will.
It’s nice that (maybe) there’s six of them inside a 9v, but there are also (probably) massive diamonds at Jupiters core. Which is also nice, and also about the same level of usefulness.
I’m slowly converting my test gear from 9v to lithium+boost, USB charged, so my need for 9v is vanishing too. (One I did as QI for amusement.)
Although a somewhat uncommon size for individual single disposable cells, I actually have a Motorola bluetooth earpiece that uses AAAA cells to make it smaller and lighter weight than if it were to use AAA cells.
Wally world sells the off branded 48 AA for around $10. That’s going to be 24 pairs of batteries for replacement.
AA cells capacities are in the 2AHr -ish range. With a correctly designed boost circuit, you get to the 1AHr for 5V and significant more at 3.3V. How close are you to that from a crappy 9V battery? BTW Cheap Chinese boost circuit are around $1 range.
The extra complexity can be paid off by the time you replace enough of the crappy 9V on a linear regulator vs 1 pair of AA.
Right. This is about the worst design you could do today. The 1970’s are over and we have newer tech than amazingly overpriced yet surprisingly weak 9V batteries paired with a old and wasteful LM317 linear regulator (not switching, nor even LDO). You’re wasting a large percentage of your overpriced power here, and also using a device that can barely handle the dissipation it will generate. The soldering job is very “n00b at SMT” too. 0805 is really easy to solder even for hobbyists (I’ve seen better PCBs done by hobbyists on free software too). Then again, there is no real point to picking ENIG over HASL here (more expensive, no real gain).
Just take cheapo AA NIMH batteries or 18650’s (charged via TP4056’s or whatever) with a simple buck/boost depending on on many batteries you’ll use and the voltage(s) you need. It’s damn simple to make this stuff, the parts are cheap, widely available and easy to solder.
There are far nicer/better designed 5v/3.3v breadboard PSUs that run from USB for $1 on ebay, including delivery. If all you need is 5V, then most USB battery bank thingies would work too. This is in no way worth anywhere near $9.99, sorry.
Just wanted to note, ENIG + purple board is most likely “I used OSHPark for this PCB”, not “I think I need ENIG”. Everything in the batch order is purple, has an ENIG finish, and costs flat $5/in^2 for 3 copies of the board, no other fees. So, not so crazy on /that/ part.
Here’s a quick design I did tonight based on one AA battery and a boost. This is based on a different project that I had, so I know the design works well. It’s only currently designed for one voltage, but it would be possible to make the voltages switchable. If people are interested in this, drop a line on the project page and I’ll put a bit more effort into it: https://hackaday.io/project/7050-aa-breadboard-power
There’s not much capacity in a 9-volt battery. So a small effective buck converter might have been better, but it would destroy the simpleness of this.
8/10 Would buy ;)
Not very efficient using a linear regulator to drop to 5 or 3.3V.
Yeah, I cringed a little when I saw he wasn’t using a switching regulator.
Cost and complexity are the issues. I am designing one with a switching regulator as well.
Considering the high price of 9V batteries, I feel like spending an extra few bucks on the board gets more than made up for after running through a couple of battery lifetimes. This is especially true when using the 3.3V output, where you’re burning up more than half of the battery on just the regulator. So seems like cost shouldn’t be much of an issue.
I can concede that switching supplies can be more complex (higher part counts, more parameters to worry about), but they make some fairly easy to use buck regulators with integrated FETs that just require a Schottky diode, an inductor, a couple caps, and some resistors for setting the output voltage. Something like the LM2672-ADJ comes in not-impossible-to-solder packages, though it might be tricky fitting that on top of a 9V battery.
Anyway, I’m glad to hear you’re making a switching version. Good luck!
I actually just put together my first switching regulator with an AOZ1282 to power an ESP from a 24V supply – I was thoroughly surprised when (once I corrected the lack of a bottom layer on the board… with the power traces and ground plane on it. oops.) the thing just /worked/. Low-melt lead free solder and a hot plate to put it together and the SOT26 footprint was much more forgiving than I really would have trusted it to be – spent way too much time trying to get the solder reasonable, and then it had obviously huge tolerances.
So yeah, switching regulators for the win.
Go the other direction. Use a couple of AA cells and a boost circuit. You’ll get better capacity/dollar out of it than a 9V design. They sell bulk packs of AA cells in stores for the same price of a handful of 9V.
Thanks! I am looking at the TPS63060 currently…
Chinese breadboards suck even more. I bought ten at $3 each. The connections are usually 2 to 4 ohms.
When you can get the hookup wires in to the tie points at all even using pliers and excessive force. I have bought cheap breadboards and will not again.
+100
Or even 6 Ohms for some. They’re not made with copper; probably stainless steel.
http://nerdralph.blogspot.ca/2014/07/busting-up-breadboard.html?m=1
From my experience, they don’t seem to or bother to get the metal right for the cheap stuff. At least they have improved on their plastics and PCB a bit.
A USB battery is a simple rechargeable source of 5 volts. Some timeout when the circuit draws too little power, but it’s not hard to find ones that don’t or make a circuit to keep the battery awake.
Yup, best option IMHO, especially if you can salvage some 18650 cells from laptop batteries to lower the price.
I use a USB output for a power supply.
be careful probing gadgets connected to your desktop pc with a scope though.
He’s hoping to sell these for $10 each – better spend the money on a cheap bench PSU, IMO.
The issue is the volume. I’d love to sell this for $5. It just means more initial investment and greater risk for me. I am seriously considering it though.
It’s simple, easy and it you can’t be near to your bench supply when working on something it would save a lot of hassle. I don’t think he thought he was going to be replacing bench supplies. I think it would be great if you needed a quick and dirty 5v/3.3v on the move.
If you’re going to the effort, why not do it properly and use a buck regulator to maximise batterly life.
And 330R for a power-on LED is also wasting a ton of power.
But the Arduino tutorials tells you to use a 330R resistor for blinking your LEDs..
The photo is of an early prototype. I’ve used a 1K resistor for the latest version. I thought of dropping the LED altogether, but looks like it might be useful to have.
Like this: http://hackaday.com/2015/05/13/hackaday-prize-entry-a-7805-replacement/ perhaps?
Pretty good idea, many times I’ve had to build a small circuit to test something but had to take the breadboard to the device for testing. Obviously several posters here never leave their bench, not all scenarios allow access to USB, no way I’m dragging a laptop or power supply with me, a 9v simply works as a small portable power supply that supplies enough power for more than enough time to fully test the circuit without having to find an alternative. Thumbs up.
I know I live in the greatest city in the whole world and so no one else will have these devices, but in my city they sell 2000+mah batteries for about the same price as a pack of duracells. Pay a bit more and you can get 10000mah@2.5amps in a form factor only slightly larger than your precious 9volt.
a 9v battery gives like 30mah @500 ma. Its time for you to put down your sticks, come out of the cave, and join the rest of us in the modern world.
Again, a perfect example of someone with more arrogance than experience.
Ordering “special” batteries, using USB, or buck converters is fine, if that works for you, keep on keeping on.
But, there was (and is) times when such items are not practical or obtainable in time.
I’ve been in many scenarios where testing a circuit involves actually going to the device, which can be in the field, on a vehicle, or in a plant and doing various test and measurement with an experimental circuit. We use what we have, which pretty much involves standard, off the shelf products, has to done quick, sometimes without access to external power source, and in a few cases without being able to shut the device down completely.
“using a USB port” wont cut it, why drag my laptop or some other bulky device along when not needed? a 9V can be obtained anywhere, any store, and are cheap, dependable, and expendable.
Do it your way, if it works, hey, great, but understand this, there is more than one solution to a problem, and insulting his work, his design, and by implying that I “get out of a cave and join the modern world” of special batteries, well, you show your age and your IQ with such remarks, and if you made such comments on my site, you would have been dragged through the mud, banned, and all other post would have been erased.
“special batteries” that I can walk over to CVS or basically anywhere else and buy off the shelf. Regulated 5V rechargeable batteries became commonplace when everything swapped to USB as a standard for charging, and a USB connector for power also lets you run whatever it is you’re designing off of wall power or a vehicle (or keep the rechargeable charged, too) with a cheap widget and no additional effort.
This is nothing new. People have been doing things like this for years. To want 10 dollars each for them is a joke. You can already get them on eBay for a dollar each. He gave no specs to it. How much amps can you get from it? What’s the point of it when you can get little rechargeable packs now with 5volts USB output for cheap.
Sorry this was done years ago.
Happy to see my project mentioned. Thanks for all the encouraging comments. This is my first foray into manufacturing and I am doing my best to bring this out to market soon.
on 3.3v from 9v you wasting 2/3 of the battery power
No he’s not, the waste depends on how inefficient the regulator is.
A 9v battery is 6 1.5v cells in series. Typically a 1.5v cell is considered ‘flat’ at 0.8v (often higher) so if all 6 cells were discharged this far then the (considered flat) 9v battery would be outputting 4.8v. That’s still enough headroom for a 3.3v LDO regulator to work.
So yeah, that 9v battery is going to have pretty much all of its energy sucked out of it. A lot of that may be wasted by the regulator, but it won’t be 2/3rds of it.
yes, you have 4,8v when the battery is flat, but only then when you just suck no power out of it. when you try to suck some mA you come fast under the voltage where the lm317 is working…
And yes, you’re right, I have 3.3v, not 3v, so it wastes a little bit fewer than 2/3, but it wastes the most of energy of the battery. And this is not a godd idea…
Not disagreeing with out, it does waste an awful amount of power.
From a fresh battery you would be wasting 2/3rds of the power, you need to drop 9v to 3v so that extra 6v just goes in heat. The good news is efficiency goes up as the 9v battery voltage drops (the bad news is it’s ability to source current drops too).
Could be worse, if the output voltage was 5v, then this circuit would drop out when the battery went down to only 7v (LM317 has 2v headroom? 78xx do).
A quick fix is these: http://power.murata.com/data/power/dms-78xxsr.pdf, drop in 78xx replacements that would be over 90% efficient in this case. They’re a bit pricey, really meant when you’ve an existing board you don’t want to redesign (or you couldn’t be bothered doing your own switcher – like this design).
The LM317 requires a minimum load of 3-5mA (thus the 240-ish resistor in the feedback circuit). Not exactly friendly for long battery life.
Near the end of life, the extra batteries will have much higher internal resistance. Now you have 6 time of the already high internal resistance of 6 AAAA batteries, so not sure if you can get much out of it near that end.
There are already modules like this one…
You can plug it right into the breadboard.
Tested one, works quite nice.
http://m.aliexpress.com/item/1726258518.html
Is there a HackaDay Prize for worst design idea ever?
For about six dollars one can buy an adjustable boost converter, adjustable buck converter and a holder for 4 18650 Li-Ion batteries. Add some wires and header pins and you get more versatile pocket supply (that can deliver 2-3A) for all your Arduino needs. Batteries can be scavenged from old laptop battery packs, cheap chargers are cheap enough for everyone. And you don’t have to buy batteries by truckload.
Agreed. Terrible naiive design with no consideration given to thermal limiting factors and the worst choice of package for the LM317.
At 25C with 9V in and 3.3V out Tja = 53C. This device will burn up in a cloud of blue smoke at a little over 300mA output.
To be fair, it would have been a good idea in 1975 and a few years beyond.
I can’t remember the first time I saw this, although surface mount does makes for a nicer unit than ye olde through pin.
Linear regulators are good, if you are doing precise analog things. I did some time ago an ADC for low voltage/high impedance sensor that used linear regulators to achieve low noise. With two-stage auto-zero amplifier, copper rings and whatnot.
Also here one can get a DIY kit with screw terminals, LM317 and everything else for about 4USD, not counting postage. Beats this tiny dingus, becaise with heatsink it delivers 1,5A of current and is fully adjustable..
Ow. Like everyone else said. You’re taking a battery type that has lousy energy capacity and low maximum current, and then you’re throwing away either 45% or 63% of the energy it has. The usual suspects already sell boost converters that will give you 5 or 3.3 off a single AA, or the various solutions other people have recommended. Maybe if you had a huge collection of nearly-dead 9v batteries from somewhere else, and wanted an easy way to get the last bits of power out.
I’d rather use one of these: http://www.petervis.com/Raspberry_PI/Breadboard_Power_Supply/YwRobot_Breadboard_Power_Supply.html
with one of these:
http://www.amazon.com/gp/product/B004GIGU2E/
..which won’t quite work.
A lot of people seem to be ripping on you. I think it’s cool that you’ve designed something.
Unfortunately, I need to dish out some criticism too. That soldering job looks atrocious. I hope that isn’t what the end product will look like. Certainly worth getting some stencils made.
Thanks! The soldering is not mine, but by a friend who was trying to help by making a variation of my idea. My design is actually a bit different from the one displayed. It’s a tough crowd here, but I knew that before I made my design public. I am actually redesigning it to use a buck/boost converter – so some of the feedback was helpful.