Instructables
Picture of Adding 'Oomph' to the Garden Solar Light
Tired of the feeble light from your Solar-rechargeable Garden lights? You can more than triple the light output with this new circuit. Works even with red or orange lights - as long as it runs off a single AA rechargeable battery!
 
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Step 1: Remove the old circuit board.

Picture of Remove the old circuit board.
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Cut the wires as close to the board as possible. We'll need the wires from the solar cell and the battery holder, so cut them as close to the circuit board as possible. If there are wires from a light sensor (colored Green here) we can cut those too - it's not needed anymore.

The board can go and join the others we removed from other projects.

Step 2: The new turbo circuit.

Picture of The new turbo circuit.
The new circuit uses fewer parts than the original but can deliver over 80mA, almost 4-times the current to a White or Blue LED while using about 250mA, which is double the efficiency of the original design.

We will need to use 1/2W LED, which are readily available on eBay:
here, or here. They each have slightly different products, but I've used both and they're both reliable.

The real star of this circuit is the driver transistor, FJN965, from Fairchild Semi. Capable of handling up to 5-amps of current in a TO-92 case, it will start at .9v and run the light until the battery drops to under 0.3-volts. You can get them from http://fairchildsemi.com

Resistors, capacitors and inductors can be obtained from your local supply houses (eg Radio Shack, The Source), Sure Electronics, or at online surplus stores, like http://AllElectronics.com

The second image shows the layout using a Perfboard. S+ and S- indicate the wires from the Solar cell.
qs (author) 1 month ago

I've been told that Fairchild has obsoleted the FJN965, but the 2SD965 is still available and costs under 20 cents a piece. If you have eBay, you can check this:

http://www.ebay.ca/sch/Business-Industrial-/12576/i.html?_from=R40&_nkw=2sd965&_sop=15

alC113 days ago

Can you help me with this?

I have purchased the Moonrays globe type thru Walmart @ $12 to $15 each. After about 8 months some of them are developing the following problem: the Circuit or the Photocells are going bad. What I mean is that the "Moonray" brand 1.2v AA NI-Co batteries will not recharge in the unit. When I swap in a regular AA (for test purposes only) the light will glow. When I insert the suspect battery into another unit, it recharges fine and works well. This is the 4th one to exhibit this problem, and since I am heavily invested into this unit (I have about 40 of them operating around my property) I want to be able to repair them. I can upload a pic of board if that will help.

dawp1 year ago
This may be a bit off-topic, but I was having a problem with solar powered lights not lasting through the night. I was using the type with one Ni-CAD or NiMH cell. I put an ordinary AA alkaline battery in one and found it burned brighly all night. What is more, the lights have continued to operate this way for over two weeks. I can only conclude one of the following (1) there is enough energy in a non-rechargeable to outlast a rechargeable or (2) As in some of the advertised devices that recharge alkaline batteries, the solar cells in the light provide a sufficient recharge to keep the battery going. (3) The rechargeable batteries that come with solar lights are of inferior quality. I I tend to go with option (2). Has anyone else done this?
netdragon dawp3 months ago

dawp: This is VERY dangerous. Your solar panel is probably not going to be able to tell it's an alkaline, and your alkaline has been CHARGING! Heck, even most chargers don't have a safety mechanism to prevent charging alkalines. Lucky for you, the solar panels are only drip-charging the alkalines. Eventually, it'll burst, maybe within the year, and cause a nice little mess inside your light's battery chamber. It could potentially cause a fire or explosion as well. That's unlikely due to the speed at which it's charging, but I have to tell you it's possible. There's whole discussions about drip-charging alkalines. It's dangerous for those who don't know what they are doing, and there's a reason why commercial companies say NEVER to do it.


The effect you are seeing is that alkalines have a lot more energy density than rechargeable batteries. It's a bit of a trade-off. Plus, since you've been drip-charging the alkaline, it's lasting even longer than it otherwise would. Considering even efficient circuits are still going to draw 100mAh or more, were it not charging, it'd have died within the week.

Also, please view webgiant's response with extreme skepticism. Amp hours are a measure of energy, not power. And as I mentioned, alkalines are typically higher energy density than rechargeables, with the exception of lithium ion, which I'd highly recommend against using outside. Lithium catches fire with a nice giant green flame when it gets wet, and can explode if in high enough quantities.

webgiant dawp5 months ago

The option you have not considered, regarding your solar lights not lasting through the night, is that the sun falling where you have your solar lights did not fully recharge the original battery. Based on the solar cell size and composition (generally amorphous, which is less efficient than mono/polycrystalline silicon), most garden lights, even in full sun all day long, will still not charge the battery enough to last all night long. Solar garden lights are intended to provide light for about four to six hours in full sun, less in less sun.

As an alkaline battery is charged in a completely different circuit than one used for NiCd or NiMH batteries, what is more likely happening is that your garden lights are simply running off the battery without the solar cell being involved, other than to shut off the light in the daytime. A full charge battery, such as an alkaline, can keep a single LED light on for 1-2 weeks, especially if it only runs at night, without recharging the battery. The LED "throwies" you may have seen on Instructables run for 1-2 weeks on a similar non-rechargeable battery, and they don't shut off in the daytime.

A fully-charged rechargeable battery has at least the same, if not more, amp-hours of power (amperage) than a regular non-rechargeable battery. With solar garden lights you get what you pay for, so rechargeable batteries in cheap solar lights will probably be cheap as well. Some of them last for years while others do not last very long at all.

JLouisR1 year ago
Hello; on my lamps I have also glued a new cell at 45 degrees facing south to get more light especially in winter. The problem may come from overcharge in summer if the new 2000mAh battery you put is Ni-Mh.I think It would not be possible to put even a simple TL432 shunt regulator, because end of charge on NiMh is difficult to detect with easy circuit. You can see the lights I fixed on my site, just for images because it is in french:.http://jeanlouis.ramel.free.fr/spip.php?article41
dph9872 years ago
Here is a spice simulation of the new turbo circuit. I have substituted an FZT849 for the FJN965 being the closest type available in the simulator (8 amp) and I needed to reduce the 1meg resistor down to 100k before it would operate properly. I also found that increasing the 1 microF cap to 2 microF in the peak detector arm improved its voltage stability but takes slightly longer to startup.

However, I also found that this circuit will not start if the voltage is below 1.1 volts (!). It should work down to at least 0.8 volts to be usable.
ltspice simulation3.jpg
qs (author)  dph9872 years ago
Even if SPICE is getting close to real-world performance, it's not a valid emulation if you substitute a part that has less than 1/2 the gain of the FJN- / 2SD965. The 2SC2500 is also acceptable.

Your observation about the 10uF cap is a valid one - it does improve the operation somewhat.

This circuit was designed to make use of the power curve of the NiCad cell, so operation below 1-volt was not a consideration. However, for other applications, substituting a Schottky diode for the 1N4148 / 1N914 will allow the circuit to start at 0.7-volt and continue running until 0.4-volt.

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s12 years ago
Plenty of 2SD965 on ebay.

I would like to first thank the original poster for this circuit.
I have been trying to build one of these myself using this schematic as a guide. Unfortunately, I cannot get an FJN965, and so I have used the NTE11 which is apparently an equivalent component( I think the pin out may be different though). I have used a discrete inductor as well as a wound one that I have made, and I am still having trouble with getting the voltage to boost to 3.3 V , though it does turn on and off depending on whether sun is out or not ( turns on when I cover with my hand and turns off when I let the light hit my solar panel ). My battery voltage is mimiced at the LED.
qs (author)  Now_Is_The_Time3 years ago
If all you is 1.2v at the LEDs, then the transistors are not owrking - check the transistors (polarity, pins, etc.) and the diode, D2 - it should be a low-signal silicon diode, 1N914 or 1N4148 or equivalent. Do not use a power unit. The 1uF capacitor at the anode of D2 is also critical.
jsilvers1 qs2 years ago
do u have a parts list for this build
Yes I am using a 1N914 and have the 1 uF, but I may have the pins switched around as again it is a brand-equivalent, yet different transistor. Thanks for that input. I will test it some more soon, and reply back.
please explain the operational for the circuit..
qs (author)  emy vesverus4 years ago
It's an adaptation of the 'turbo-charged' 2-transistor Joule Thief circuit which was presented on my web-site. Take a look there first and I'll try and answer any specific questions you have.
emy vesverus qs4 years ago
QS...i just wanna ask...why when i change the battery to (6V,1300mAh) and the solar panel to (7.2v,1W), "i had remove the inductor"...the LED always On at day and night... sorry i'm still new in electronic...
qs (author)  emy vesverus4 years ago
This design is specifically for converting the power of a 1.2v battery to 3.3v needed to operated the LED. By using a much higher supply, you're forcing the circuit into unknown, and possibly unhealthy areas.

If you have a 6v supply already, then you will not need to 'up-vert' the voltage at all. Just connect the LEDs through a suitable resistor and add a light-sensing switch for day/night operation.

Hope this helps - let me know your exact application (# LEDs, etc) and I can provide more help in assembling your light.
rmfungaro4 years ago
QS can use an inductor 47uF in this project? 22uf not find in my area ... congratulations for the project!
qs (author)  rmfungaro4 years ago
The acceptable range for the coil is 15-30uH, so 47uH is too high.

If you have 15-ft (5m) if a thin insulated wire, you can make your own - just wind the wire around the barrel of a felt marker (anything 1/2", 12mm in diameter will work). You don't need to be neat, just jumble wind into a donut shape and tie or tape together after removing from the form. This will give you a 22uH air-core inductor, and will be able to handle up to 1-A of current.

You can also get an assortment quite cheaply here on eBay.
clever stuff . i have much to learn
chadeau4 years ago
So radically convenient-totally understand-cell repl sensor by input reduction-GREAT ! Thanks...
chadeau4 years ago
Is sensor connected after testing,or ...
qs (author)  chadeau4 years ago
The sensor is not needed since the circuit actually measures output from the Solar cell, and only turns on when there is less than 0.3v output, which is deep twilight, before turning itself on.
Rusdy5 years ago
Oops, forgot to add photo of mine, using slightly modified your circuit
IMG_5828.jpg
qs (author)  Rusdy5 years ago
And thank YOU for sharing Rusdy! Fantastic job! With the added boost to the base drive, it is sometimes tricky to turn off using the solar cell - sometimes their internal leakage is high enough to bias oscillations on. The FPN965 is available on eBay (possibly as 2SD965) for 15 cents apiece. I prefer thru-hole components to SMT anytime.
Rusdy5 years ago
Thanks for sharing the circuit qs! After experimenting myself with different circuits and component values, yours is definitely the best! I'm using your double coil configuration (from your website for garden light). Unfortunately, the LED doesn't turn off until there is quite a bit of light, so I have to modify it with adding a second transistor. Anyway, getting cheap components is a major problem here down under, so I have to change the transistor (using FMMT617 instead of FJN965). After many (lots) of iteration, at last my lightbox is finished (well, actually still evolving!)
Wesley6665 years ago
Cool instructable. I was disappointed though, the name said Oomph and as stupid as I was I thought you were adding music to the solar lights (I am German and there is a band named Oomph!) so naturally I was curious. Nice Instructable though.
qs (author)  Wesley6665 years ago
LOL!

Lost something in the translation huh? I have a project which involves music here.
Wesley666 qs5 years ago
Cool music Instructable! I don't have an Arduino = ( I should get one.
could i use this same design and replace one solar cell with four in parralell and supplement the one aa battery with 4 aa ? or would that through all the voltage off?
Explain to me your needs - are you planning to run more LEDs? How bright? If you are not going to use the Garden Light enclosure (and solar cell), then there are different options available.
OK I bought 4 working solar garden lights from wal mart @ 4.00 a pop (would have recycled broken ones but couldn't obtain any) So, I want to make a modded light out all the parts I have a set up for a container I am working on from cd spindles and I have perfboard and a separate battery pack thats holds 4 AAs, I basically want to compile one circuit 4 battery's and 4 cells, I also bought some bigger LEDs from radio shack rated @28,500 mcd FW current 20 mA FW supply 3.5v 4.0 max, I would also like to wire in the photocell, but also have a on/off switch I am familiar with basic electronics, but can't really read schematics yet, I'm thinking of trying to integrate your circuitry with either a few standard LEDs or one of the big ones I mentioned earlier with 4 solar cells 4 AAs a ,a on and off switch, a potentiometer in the battery line to control brightness to extend battery life and maybe the photo cell to allow it to double as a outdoor light I'm aiming for a indoor outdoor solar light (with removable extendible solar cells for when indoors, photocell when used as a auto/on porch light) sorry for all the detail but from all the Instructables I keep winding back up on yours thinking the answer I need for the better power regulation/rebuilt circuit is there I just don't know enough about electronics to reverse apply it to my own needs, by myself.... but anyways room isn't much of an issue and I can wing everything besides the circuitry, because I don't want to fry my parts ect..
qs (author)  digitalenigma5 years ago
So, you are basically going to rip the lights apart for parts.

And with thise parts you want to assemble a single light with 4 LEDs. is that right?

Then the simple solution is to take 3 batteries, and charge them with 3 solar cells with a diode in between - like the picture below.

My suggestion is to charge the lights up first and see how well they serve your lighting needs. If mains power is avilable, it may be a better solution to build a LED "bulb" like this one here, which has the brightness of a 25-40watt bulb but only uses 3 watts for under $10.

If you bought the 10mm LEDs from RS, then be warned - they are not "brighter" they just have the beam more focused - so it forms a very tiny spot of light, so they may not suit your needs.
SimpleLED.jpg
Rusdy qs5 years ago
I definitely like your 'simple' approach. But, I found using rechargeable batteries in series is very likely to damage one of the battery too quick (uneven charging / discharging cycle). So make sure to use fresh same batteries if you want to do this. All my solar garden light fails the same way, that is, one of the battery fails earlier than the other, causing charge reversal. So, I definitely like your single battery solution instead. Though, your 250mA current consumption will definitely make it last a wee bit too short. I'm trying to use LM2623 at the moment, definitely can't beat the efficiency from the chip manufacturer :) (70% as it claimed by the application note AN1221, April 2002 edition from the manufacturer). The only problem is, this chip only available in surface mount. So far, the pain of getting surface mount components, backyard job on surface mount PCB, and soldering them... still progressing. Painstakingly slow for a newbie in surface mount like myself :( All in all, I like your simple solution :)
no im definatly wanting to experiment wth solar/renewables, i could buy a led bulb but i was just in the middle of the southern us ice storm, and more than ever i realise the value of things that dont plug in! but yhea ive already disasembled the lights minus the circut boards and have been experimenting with them on a breadboard, so im going to save your scematic above and see what comes about, thanks very much for the info , the pic looks much simpler than what i had in mind or what comes in the factory circut!
qs (author)  digitalenigma5 years ago
The simplicity comes from the fact that 3 NiCd batteries just happen to fit the voltage of the white LED almost perfectly. That is why there is a minimum of adjusting and fussing.
peppeska5 years ago
Hi!!! Thanks!

Great Job and great instruction!

here my job! -> http://peppeska.wordpress.com/2009/04/04/pimp-my-solar-garden-light/

and here my circuit ->

th-img_3368.jpgth-img_3369.jpg
;)
ALadyDragon5 years ago
Could i get a break down of the bits used. Im very very new to these kind of map and need a little more help. I want to try and get my old solar garden lights a make over and i feel this might just do the trick.. I just need some help.
qs (author)  ALadyDragon5 years ago
I'm in the process of updating this design - to a flashing version. If maximum attention is what you want, perhaps you can wait a few days - otherwise, let me know and I'll put up a list of components and try and answer your questions.
ALadyDragon qs5 years ago
Hey thanks for the feedback. i will wait for the flashing version to come out. it might give me more to go on.. I just finished making clifford the cricket (so im very very basic) I have just replaced some of the batteries in the solar garden lights - testing to see how they go the others are in a bag waiting, so no hurry. Thankyou again :)
does the FJN965 have to be from Fairchild Semi? i think i have but idont think its from there, its older
qs (author)  digitalenigma5 years ago
The FJN965 is Fairchild's rebranded version of the 2SD965. You can substitute the 2SC2500 here as well.
saltoricco5 years ago
Just the thing I need to illuminate our street number sign. Thanks a lot for posting! One question: Would it be possible to power two or three LEDs with that setup?
qs (author)  saltoricco5 years ago
This design will drive a 100mA LED, which translates to 5 regular LEDs at 20mA. You can go as high as 8 of them in PARALLEL before it is noticeably dimmer. If you are doing red LEDs, with much lower voltage requirements, you can drive as many as 12.
saltoricco qs5 years ago
Thank you for your reply, qs. How should I wire those, in series? I remember dimply there would have to be some resistors somewhere too, but where and which? Thanks again, appreciate your sharing!
qs (author)  saltoricco5 years ago
If you plan on using multiple LEDs you should connect them in PARALLEL, and they should all be the same type of LEDs (or pre-tested for similarity in voltage requirements).

To connect LEDs in parallel, you have to connect ALL the positive (longer) leads together and all the negatives together. The circuit is inherently current limited to about 100mA, so as long as your LEDs can handle 100mA it should be fine.

An advantage of LEDs (over incandescents) is that they work almost as well even at 75% of their rated current, so you can add 50% more LEDs and they will not look washed out.
saltoricco qs5 years ago
Perfect! I'll wire them in parallel just like light bulbs then. Thanks a ton again for your help! Here is the number sign: http://www.shadowbrush.org/blog/wp-content/uploads/2008/11/img_0714.jpg I tried to illuminate it with one LED but it needs a brighter one (like what you used), but I think even better will be three for the three digits. I might get a chipped or broken solar to help charge the battery. Have a good weekend!
razwan.z5 years ago
great job on the mod! but i do like to know what happened to the light sensor.. perhaps you could explain more on that part as i dont see any connection on them onto your 'oomph' circuitry..
qs (author)  razwan.z5 years ago
Instead of the light sensor, the circuit monitors the output of the solar cells: no voltage = no sun, and turns on using that instead. That is why there is a 1MegOhm resistor connected to the Solar cell on the 'wrong' side of the diode.
kill-a-watt6 years ago
Since you now are using more power for the LED, and you did not upgrade the solar cells, are you going to have an issue with the length of time the light burns or deep-cycling of the battery? Oh and is there some electrical reason why those lawn led lights come with NiCad batteries rather that NiMH? The only thing I am aware of is that the NiCads can be "dumb" charged at a higher rate than NiMH.
the main reason i believe that NiCads are still found in "cheap" electronic devices is because the source of the "made in...." country still makes crap that sells. they make the out-dated batteries because it still sells and have no financial reason to change to the more recent Ni-Mh's.....even though THEY are on their way out and being replaced with LI-Ions too. so blame cheap manufacturing and countries that have little reason to upgrade and evolve...and the people that constantly buy the cheap products to keep the cycle going :(
(I did not read your last step before commenting)
qs (author)  kill-a-watt6 years ago
Among other things, this circuit really shows how weak the included NiCds are - almost half lasted just weeks before dying completely. Deep, deep discharges coupled with overcharging the culprit no doubt. btw, I also tried "Nexcell" 1800mAH NiMHs which also did not last. Doubling up on the solar cells provided almost continuous recharging - since they could deliver almost 2v even without direct sunlight.
=SMART=6 years ago
NIce !
Mr. Rig It6 years ago
Cool project and it came out well, good job.
qs (author)  Mr. Rig It6 years ago
Thanks! I like your Underdog avatar!