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  • Efficient automatic solar garder lights circuit with minimum components the best deal is that is completely auto and the Solar panel acts as a light detector. Switches the Lamp off at Dawn, charges the battery during daytime and switches the LED lights ON at dusk providing 100 Lumens illumination during the night.

    The solar panel must provide 5.5V and 150mA. Assuming a 3.7V/1500mAh battery the charging will be complete in 8 hours at 200% capacity @ 180 mA. With 10 LEDs the power consumption would be 90 mA/hour providing a 10 hours illumination with light levels of 50 lumens to 60 lumens. With 20 LEDs the light intensity will be 100 to 120 lumens.

    You can use any number of LEDs and battery capacity too. This would directly provide you the amount of illumination and time for illumination. If you use higher capacity battery than that recommended the solar panel current should be increased proportionately. Current provided by solar panel should be 10% of battery capacity.

    Solar garden lights circuit schematic

    automatic solar garden light circuit schematic

    automatic solar garden light pcb

    Bill of material for the solar garden lights

    • Resistor (1) 4K7 or 5K6
    • Resistor (1) 47E or 56E or any value ( Current Limiting )
    • Transistor 2N3906
    • Diode  1N4001/7/ 1N4148 (Any)
    • Solar Panel 5.5v/200mA
    • Battery 3.7v/1500mAh
    • Switch SPST
    ask a question

    92 Responses to "Automatic Solar Garden Lights with LEDs"

    1. The transistor is 2n3906.

      • Dear Sir,

        Thanks you so much for your circuit. Solar lamps are my bobbie, and I’m not a profesional of that (I’m a Scientist in Veterinary Research). I have builded your circuit but I have found that the tension around the led is too low 2.7v, I have checked all the details and I can not find the mistake, may you help me?

        thanks a lot in advance



      • Fernando says: on June 18, 2014 at 2:53 pm

        Assuming its a 3.7V battery, after the transistor the tension is already 3.1V, since we also have a resistor (current limiter) in the way, the tension drops a little bit more, as the resistor is in series with the leds. To be honest, there is no way you can put the 3.3V if you dont change the circuit, and you cant take off the 47 ohm resistor, even if you low it down, it will still be around 2.7V on the Leds.

    2. Jim Keith Jim Keith says: on July 23, 2012 at 10:01 pm

      Very clever, but simple circuit.
      If solar cells have insufficient reverse leakage, transistor may not turn on at night–may require a 47K resistor across solar cells–keep this in mind

      • Keith welcome your observations . Our philosophy is Keep things simple. Yes it does light up a little before dusk ( If it get dark by 7 this would start 45 minutes earlier. this problem is settled by using another 2.7K to 3.3 K resistor in series with the 47K resistor(50K in lieu of 47K) 50 K is not available

        We have observed that there is profit in making things seem complex. We humans tend to make the process as complicated as possible by trying to improve in complex machines but a simple approach is still possible.

        Try the same which i believe you may have as it takes less than 5 minutes to build and watch the results. What we have put in the public domain is a working kit way past protypes. The beauty of this is that you can use as many LED as you want from 1 to 20 depending on your illumination needs and Battery capacity.

        This is a very basic circuit and we use it as switcher in our other circuits.

        We have added a switch (SPST) between the 47E Resistor and the LEDs to keep it off when not in use for prolonged periods.

        Her again the beauty is that you can use any resistor(current limiting from 22E to 100E as per you Illumination needs and battery capacity

        The only problem seems to be good quality Cells(Battery) against cost. With better quality and prices dropping we have managed to keep this kit to below $5.

    3. aniltvmin says: on July 27, 2012 at 9:22 am

      incredibly SIMPLE circuit….thanks

    4. Pentaconto says: on July 27, 2012 at 8:34 pm

      Hello to all:

      This post is not complete (for me): in all posts of electronics circuits with PCB, please to inclose also the parts (electronic components) distribution in the PCB, is userfull for to make easy building the circuit.

      Greetings from Barcelona (Spain)

    5. Pentaconto do you wish to buy the kit ytou are welcome

      • Sebastian Kushero, I would be interest in buying a few of the circuit (automatic solar) to try them on a few I have andnot working anymore. the battery is not charging or discharging. when I connect a good baterry the light stays on even during the day. send me private at matosw at gmail. thanks

    6. Hello,

      In your article you state “The battery is a 3.7V/1500mAh type and it is charged at 80% capacity in 10 hours.”

      Isn’t this a Li-Ion cellphone Battery? If so, I thought they need a special charge management controller to prevent fires and bursting from overcharging past 4.2v?

      • Jeff We Can offer you two options but this was for NiCad cells where charging current was to be 10% of battery capacity. Yes this is a very basic circuit mainly used for switching in our other applications
        Maximum Ratings & Thermal Characteristics Ratings

        Collector-Emitter Voltage –VCEO 40 V
        Collector-Base Voltage –VCBO 40 V
        Emitter-Base Voltage –VEBO 5.0 V
        Collector Current –IC 200 mA
        Power Dissipation TA = 25°C Ptot 625mW
        TC = 25°C 1.5 W
        Thermal Resistance Junction to Ambient Air RΘJA 250(1) °C/W
        Junction Temperature Tj 150 °C
        Storage Temperature Range TS –65 to +150

        1. In lieu of 1N4001 you could use Central Semiconductor(1N749A) to clamp down the voltage of Fairchild (1N4731A) sacrificing on the efficiency . The Circuit is designed for Solar application where there is guaranteed shut down at dusk and unlike Ac application where it would be kept on for prolonged periods. regards the wattage of the diodes 1/2 a watt would be sufficient

        2. Or add a couple of diodes in series to the 1N4001 to drop the voltage as per desire.

    7. Jeff another solution would be to get 4.5V Solar panels which would be hard for the amateur hobbyist to acquire. a 5V panel with a drop of 0.6v would give you the desired voltage

    8. LED 11-20 may not light up as the p-Line is not connected this has been deliberate as you may want to light just 10 LED’s if you need to light up 20 connect the p line (thinner trace) any where between LED 11 and 15 .

    9. fireofenergy says: on August 7, 2012 at 7:00 am

      It seems it would light up during the day. The little bit of current going through the 47K resister opens the transistor… in the daytime. You need another transistor “for the solar panel” called Q1 which opens the gate (or base). Very little battery current is thus allowed to go through the collector and emitter. But when there’s no solar panel current, the closed gate forces the little bit of wasted battery current to open the gate of… Q2, The “led(s)” transistor.
      I have made a few such auto solar lights as high as 500mA, the max rating of the 2n22 (I forgot the real name of that transistor), and up to 12v.
      I think my name links to the actual circuit diagram on my page…

      • We welcome your input but we do ask you to build the same on a single white LED. and then use as many as you need . We do not think this problem would occur.

        Circuits provided by us here are tried tested simple with minimum components. We aim to enable the beginner enjoy his experience in building circuits that actually work, are practical and useful.

        Do write to us and send us an email from our website if you click on the name it takes you to the website and contact us on the contact page we would love to exchange views and learn and also put theories to the test. We are a research LAB with over 25 patents and 50 working models in LED.

        One such is the lighting of 60 WHITE LED’S with 2.4V/800mAh Battery ( Series of 2 on a string and 30 strings for 8 hours) with power consumption of 80mA about .250W)

      • fireofenergy says: on December 19, 2012 at 11:56 pm

        When I posted the above, I didn’t realize there was such a transistor that turned OFF when a little current at the base. Thanks!

    10. aniltvmin says: on August 7, 2012 at 1:37 pm

      Can you share the circuit for lighting 60 white leds with 2.4 volt battery…. pls….?

    11. can u use battery of 1020mAh battery and solar cells instaed of solar panel??

    12. can i use 1020mAh battery and solar cells instaed of solar panel??

      • Neha You can use any capacity battery from 600mAh . NO you can use solar cell ( For us a solar cell typicall means a single cell which is about .5v and gives about 100mA.) so you may have to wire together 11 Solar cell to give you 5.5v and 100mA to charge your battery of 1020mAh

        Visit us on our website and you can download the Understanding Solar Energy from the website.

    13. i used 920mAh battery and 4 solar cell in series of 1.5V and 100mAh each bt circuit ix not working…!

      • Neha would request you to contact us through the website which you can get when you click on the name in the post. it will take you to our website and you can contact us from the contact page there.

        Now let me assume your work you have used four solar cells in series (4*.5v = 2V/100mAh)you have to add another 6 minimum to provide the additional 3V.

        You have not mentioned the battery.
        The White LED have a characteristic voltage of 3.2 to 3.6 volts ..

        Please get the data sheet for the 2N3906 Transistor its a PNP and when you hold the flat surface towards you the emitter would be PIN no 1(EBC = 123)

        1. Use your mobile charger which would supply about 4.2 to 5v where the solar panel(Cell). and see if the same works. OR
        Another test we use is to short the leads that go to the Solar panel. The LED will light. do not do this often or longer than a few seconds.

        2. At present your solar cell is lower just 2v instead of recommended 5.5v.

        3.At times due to overheating during soldering,the transistor may be damaged. A trick i learned as a beginner is to hold the pins of the transistor or any component for soldering with a tweezer.( the type that clasp always and have to be pressed to be opened)

        4. RE-Check the pin-outs of the 2N3906. 1=E 2= B 3= C


        CLICK ON : PCB and components placement .rar

    14. im not geting your resquest of website ….cant u help me 4rm here plx……………! my solar cell voltage rating is 1.5V means 4 solar cell in series means 1.5*4=6V thats quit enough i thnk

    15. battery ix of 3.6V and 920mAh(actually its a mobile battery)

      • The battery seems okay . if you do download the PCB file you would find the email address there and could you please send the connections you have done so that we can respond . When you say your cell is of 1.5v it seems you have diddferent cells . Typically the cells we procure are of 0.5v and carry a 100mA current abt 50mW per cell . also in series a 1.5*4=6 that mean you have connected the +ve lead from the cell to the -ve lead of the othere panel . and you would have one positive and one negative lead .

        Test the same with 5.1v from any charger in place of the Solar panel.

    16. circuit connections are same as u gave bt leds are not glowing……..and how to connect charger with circuit ??(in absence of sun light current should travel through emitter and collector and should glow the leds but thats not happening in actual)

    17. i ground the base to complete the battery path without solar

    18. can you tell me properly the working of this crkt,i hv understood till transistor is off and battery follow path from emitter to collector glowing leds,,,,,,but when transistor is on due to solar energy how battery charges at this tym? and why leds are not glowing? what is the path of current at that momoent

    19. hi i am new to building electronic circuits,in this project i am finding it difficult to get solar panel of 5.5v,200ma instead what are other panel options i can use for these project??actually getting the desired milliamps is a problem.

      • It does not matter and is not critical it would take longer to charge the battery @ 200ma if it takes 10 hrs then @50mA it would take 4 times longer

      • hi,thanks for your reply actually what i mean’t was, can i use a 6v,200ma panel with this same circuit??

      • You’d have to regulate the voltage to the battery by adding a zener to ensure it gets just 4.2V . The 6 V panel would give you voltage from 6 to 9 volts which would burn the battery and also cause an explosion.

        if you are using the 6 volt panel suggest you use a 6V battery

    20. hi would you please tell me where can i order a 5.5v 200mA solar panel in india??

      • it would be difficult to get hold of the solar panels in India you may get hold of 5V/100ma solar nmodules from Vegakit in Mumbai
        Your option would be to drop 9V to 5.5 use diodes to drop the same or a zener of 6.2/1W (The voltage would be approx 6.2.- .6 = 5.6v) in lieu of the 4001
        Please use a 1W zener or higher this would regulate the voltage
        Wishing you all the best.

      • It would be difficult to get hold of the solar panels in India you may get hold of 5V/100ma solar nmodules from Vegakit in Mumbai

    21. Your option would be to drop 9V to 5.5 use a zener of 6.2/1W in lieu of the 4001 (The voltage would be approx 5.6v

      Please use a 1W zener or higher this would regulate the voltage
      Wishing you all the best.

    22. thank’s for the reply,will start with the circuit very soon.

    23. hi.is 4K7 & 47k resistor of same value???

    24. what is the watt rating for resistor’s to be used???

    25. can you tell me properly the working of this crkt,i hv understood till transistor is off and battery follow path from emitter to collector glowing leds,,,,,,but when transistor is on due to solar energy how battery charges at this tym? and why leds are not glowing? what is the path of current at that moment

    26. Suchithra Mohan says: on October 9, 2012 at 7:29 pm

      Not original circuits. All Solar Circuits were copied & slightly modified by the author! Ref this http://www.evilmadscientist.com/2008/simple-solar-circuits/

    27. Hello Dear,
      Please Suggest me a circuit, with 6V Solar panel, 6V SLA Battery, 1W High power LED.
      With Battery full and drop Indicator.
      Thank You.

    28. Hi… Thanks for the circuit. Is there any risk of overcharging the battery? Can I use this circuit for a commercial product?

      • No the max voltage you would get for charging would be 4.2v which would be ideal for battery

        Yes there is the possibility if you use a 6v panel its advisable to use a regulating sener of 4.3v for regulation

    29. Could you please tell me what resistor 56E means?
      is it same as 56 Ohm?
      what is the wattage of this resistor?

      • Jim Keith Jim Keith says: on November 20, 2012 at 5:16 am

        Yes this is 56Ω. The “E” denotes “exponent” which in this case is assumed to be 1 that does not add any multiplier.

      • Thanks a lot Jim, I appreciate your help!

      • There’s nothing like that today. I’m more opttmisiic about the solar idea, because the wind idea seems to violate some basic laws of thermodynamics. There is a maximum percentage of the wind’s energy that a turbine can capture, and that’s nowhere near 100%. So trying to harest the energy of wind rushing by a passing car would slow the car down more than the energy one could retrieve.Solar paint exists, but is too inefficient today to be of practical use. Development continues. If someone is able to make a cheap solar paint, it will benefit not only cars, but everything. You could paint it on the umbrellas over restaurant tables. On tents. On every rooftop.The energy from solar would not carry today’s heavy cars very far. Prototype electric cars targeted at solar tend to be very light, and get 2-5 miles per kWh. That’s 10-15 miles on a day’s charge, usable in some situations. The solar would not supply enough to continuously drive the car, unfortunately.

    30. Hi, finally got the circuit done but the led light is very dim what would be the problem??? tried to bypass 56E resistor but no use, battery is fully charged. Please help me out.

    31. Hi, I’m new to making this kind of circuit. Can i use a 12V solar panel?

      • You can use a 12V panel below 1W as 3906 ideally @ abt 650mW but you would have to match a battery for the same If you intend to use a 12V panel it would be a sheer waste . suggest you try to get a 6V module
        3906 data
        Parameter Symbol Value Unit
        Collector-Emitter Voltage –VCEO 40 V
        Collector-Base Voltage –VCBO 40 V
        Emitter-Base Voltage –VEBO 5.0 V
        Collector Current –IC 200 mA
        Power Dissipation TA = 25°C
        Ptot 625 mW
        TC = 25°C 1.5 W
        Thermal Resistance Junction to Ambient Air RΘJA 250(1) °C/W Junction Temperature Tj 150 °C
        Storage Temperature Range TS –65 to +150 °C

    32. fireofenergy says: on January 8, 2013 at 6:51 pm

      Hi, grateful for the info.
      I was wondering how much current the transistor would allow if the resistor was reduced. The reason I ask is because I found a pnp transistor that works, but only allows 21 mA from a 4.1v battery (3 NiMH fully charged) and a Cree XPG led which has a Vf of just 2.61v at this current (even with just 3 ohms resisting the led!).

      Since these things are rated at least for 200 mA, I was hoping the NPN you use allows more current, not to power a bunch of little leds, but to power a single cree (Q5 or XPG, etc).


      • This is not meant for the 1W or more Cree or similar which need 350mA you would need a circuit that can provide that current.

        the idea behind this circuit is to provide simplicity and long battery life bu restricitng the current from 8mA to 20mA.

        if you use a cree 1W assuming it gives 110 Lumens @350mA yu can achieve this by use of 20Leds@5lumens each and consuming just 160mA @8/LED

        In Solar Eergy the battery drain becomes vital for it prolonged life.

      • refer to the 3906 data it can take abt 200mA

      • fireofenergy says: on January 9, 2013 at 7:04 am

        I thought the little leds are only like 3.5 Lumens each at 20 mA (or 60 lm/w). I wired up a bunch of them before but they were not nearly as bright as a Cree Q5 at only 100 mA. The XTE is more efficient than that, and the XML, up to almost 200 lumens per watt (at 100 mA)!

        I just ordered the transistor, along with a 3.9v zener diode (from Digikey) that I will put between positive and negative of a 6v, 300 mA mini panel. It will handle the current because it is a 5 watt (no resistor to slow the charging process). I have a few 1.1Ah LiFePO4 batteries (from ebay) but they should not be charged much over 3.6v. I tried a 3.6v zener, but with the blocking diode, the battery only charged up to 3.3v. It should have eventually charged up (but only with very small current would the blocking diode drop less voltage). The 3.9v zener should guarantee that the LiFePO4 never gets past 2.8v or so, which should be ok since the LiFePO4 protection pcb specs at 3.9v cut off. The LiFePO4 is the SAFEST li-ion type of battery but is not quite as energy dense. It is 3.2v nominal which is good enough for the Cree at only 2.7 or 2.8v at such low current.

        Imagine, just a 4v panel can power most all lighting needs!

        I plan on making a 1.2A, 4v panel using just 8 cells (also from ebay). Once the battery is charged, it takes VERY little current to overcharge it… hence the zener diode idea.

        I think the Cree should get like 150 to 180 lumens per watt (at just 100 mA, maybe even 200!), which is simplicity and the best very efficient (unless you know where to get super efficient little leds).

        Thanks for writing back.

    33. I am a little way behind on the latest developements in LED I have just learnt from you that a cree can provide 200Lumens @100mA. We use the 4mm Strawhat that provide us 6 lumen each @11mAa string of 20 @220mA provides 120lumens

      • I have some 8mm white strawhat LED’s that output 110000mcd at 100ma, 140° beamwidth which I think is equivalent to around 454 lumens. They are perfect for personal lighting torches in developing countries to replace kerosene lanterns.

    34. fireofenergy says: on January 9, 2013 at 8:31 pm

      I see that leds on ebay are advertized in milicandela, which is different than lumens. If two leds put out the same amount of light but one is tightly focused, they have the same lumens, but the focused one has more candela. Thus, it is hard to convert candela into lumens.
      I ordered some 8 mm strawhat leds with 110,000 milicandela. Then I went to a conversion calculator and it said like 50 lumens ( which is impossible). However, I bought a Chinese solar light for real cheap and it does have ehst looks like a 4mm strawhat led. It stays lit all night with a25 x 30 mm thin glass panel and a button cell. I am amazed by its efficiency!

    35. lookme_ram says: on January 25, 2013 at 2:44 am

      Can I use 6v 5w panel and 6v 4ah battery without any problem with this circuit.

    36. Yellowsolar says: on February 28, 2013 at 7:06 pm

      Hi everyone, I am new here.
      I am building a solar LED charger with 6v 2w solar and 20 3.6v LEDs, I need to know first can I make it with a selective switch dimmable, if yes is it better to use LM555 in PWM form or use a regulator?
      I also have a circuit from a similar light and it has a chip but I am not sure if it is LM555 or not.
      I appreciate any suggestions.

    37. Colin Mitchell has made it his business to denigrate Indian designers.

      Question to be asked is is the circuit provided by us working if it works that ends the conversation.

      Providing something simple and complicated is Colins motto.

      ellow solar enjoy the simplicity of the design and if you do wish to make something more complex its great . i would rather leave this as it is and tweak or add on to it as another project.

    38. The circuit shows no electronics knowledge AT ALL by using a 47k base resistor.
      I need not go any further.

      • I wasn’t aware you were Indian until you mentioned it.
        I simply criticized the circuit for its lack of electronic engineering.
        You can see the problems readers are having with the circuit and you haven’t helped them.
        You were unaware of the problem with the circuit.
        That’s the point I was emphasizing.

    39. You say the circuit works. How could it possibly work?
      The base current is 3.1/47,000 mA = 0.065mA
      If the transistor has a gain of 200, the collector current will be 13mA for 8 LEDs – less than 2mA each !!!!

    40. Note that the max hFE for the 2N3906 is 300. This would provide a total LED current of 19.5mA. This is likely an empirical design involving a “hot” high gain 2N3906 device. While not optimum, 19.5mA provides useful illumination. Simply reducing the 47K resistor to 4.7K will easily saturate any 2N3906 –in this case the 56Ω resistor limits max load current to approx 30mA –yes brighter, but perhaps not a big difference.

      So my recommendation is to simply drop the value of the 47K resistor to 4.7K or so.

      Regarding the LEDs, two ultrabright Cree LEDs should work well –no need for 8 devices in my opinion.

    41. Let me answer the NON TECHNICAL reply from Jim Keith.
      1. 4k7 will not saturate the transistor. It will turn it ON and allow a collector current flow. But the transistor will not be saturated.
      2. Cree LEDs require 100mA or more and this circuit is simply not suited to high-power LEDs.
      The biggest mistake with the circuit is the impedance of the solar panel when not illuminated. This is an unknown value and the whole circuit is “left up in the air” as to its ability to work.
      Finally we come to the value of the 56R. This will allow a very small current to flow as the characteristic voltage of a white LED is 3.2v to 3.6v and you have 0.2v drop across the transistor. You don’t have any voltage left for the current-limiting resistor.
      There are so many faults with this circuit that saying “but my prototype circuit worked” does not create a good circuit-design.
      You can see that some of the readers could not get the circuit to work and no answer from the designer was forthcoming.
      That’s because the circuit is SUCH A BAD DESIGN.

    42. While surfing, just got a near-similar circuit with 5K base resistor & only one LED.

      Please refer this http://www.galigear.com.au/Automatic-Solar-Garden-Light-Detecting-Darkness-Solar-Battery-Charging

    43. Colin has to actually make the circuit to take his prejudice against the asian his entire life has been spent in denigrating Asian and Indians in particular opicking faults through his theory . Well if he is sych an expert what is he doing on this site other than pciking faults on things that actually work or maybe he like to keep things complex so that he can exhibit his therotical prowess

      He is surely a racist and i believe that they actually bashed Indians in Australia

    44. I built the circuit. It took 10.5mA.
      That’s 1.25mA per LED There’s no skill in delivering 1.25mA to a LED.
      Why use a 2 watt panel?
      Why use a 1500mAHr cell?
      How much illumination do you think you will get with 1.25mA?

      I will let the other readers judge the success of the circuit.

    45. I guess after making the circuit Colin now agrees that it does work. That is the type of circuit we hobbyists like to have – simple but working!

    46. I see it took 5 months for you to reply. The internet must be very slow in India.
      Just because you get a small glow out of a LED, does not mean a successful circuit. The circuit is just a DISASTER and obviously not produced by someone with any electronics experience.
      See my website for the number of mistakes in Electronics For You magazine.
      Indians have a very limited understanding of electronics and even the Indian Professors have a disastrous number of mistakes in their designs.
      You need to listen and be wise.

      • Colin,

        Could u pls send me a simple circuit with more LEDs. May be10 or 15. I already got a solar panel of 6v/2w and two batteries of 4v. I made two circuits available in the web but even 10 LEDs are very dim.

    47. its not working

    48. Sebastian says: on April 5, 2014 at 8:22 am

      Colin Mitchel has made it his business to berate other designers especially fro Asia.

      Raed and go to his websitw and you will be shocked by his rascost and racial abuse.

      He talks theory withoit trying the circuit and i challenge him that the circuit given here is not only auccessful but excellent due to its use of minimal componemts, that what is making his professorial pigheadness nit accept that you do not live by theory or can i compare him to the pharasies of old who thinj its his domain and a black man has no place

      Yes Indians with thier backwardness has sent satellites into orbit. It time all of us starr giving this abuser Mitchell Colin back

    49. “i challenge him that the circuit given here is not only auccessful but excellent”

      zafer on April 4, 2014 at 3:28 pm
      its not working

      Colin Mitchell Colin Mitchell on March 5, 2013 at 5:03 am

      He talks theory withoit trying the circuit


      I built the circuit. It took 10.5mA.
      That’s 1.25mA per LED There’s no skill in delivering 1.25mA to a LED.

      Show me ONE PERSON who has got this circuit to work !!!!!!!!

      The circuit simply does not work.

      I advertised in Electronics Maker (Indian Magazine) (2 full pages each month) and did not get one reply or order from any hobbyist.

      Fortunately I got an Indian Professor BANNED from supplying junk projects to Electronics For You.

      Another Indian Professor said you can get 3.5v between base and emitter of a transistor.
      Luckily he has now closed his junk website.

      This SOLAR GARDEN LIGHT is another junk project.
      The author knows nothing about electronics:
      Look at this statement:
      “With 10 LEDs the power consumption would be 90 mA/hour ” ?????

    50. Here’s another person who could not get the circuit to work:

      Tacho on May 10, 2014 at 11:46 am
      Dear Sir,Thanks you so much for your circuit. Solar lamps are my hobby, and I’m not a professional of that (I’m a Scientist in Veterinary Research). I have built your circuit but I have found that the tension around the led is too low 2.7v, I have checked all the details and I can not find the mistake, may you help me?thanks a lot in advance regards tacho

      The circuit needs a voltage greater than 3.7 volts.

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