But current still reduced to 0.9amps. Supply is 24 volt 5amp. Notify me via e-mail if anyone answers my comment. And If I add a resistor means , can I get a constant input to the LED panel from the smps adapter?? ?And am having 12v 5A lead acid battery. Using the above circuit would be an overkill for your 15 ma LED. The universal high watt LED current limiter circuit explained here can be integrated with any crude DC supply source for getting an outstanding over current protection for the connected high watt LEDs. The above circuit can be very efficiently used for making precision current controlled LED tube light circuits. R2 or R10??imgur.com/12SdCvSimgur.com/dFKArEo. Hello Abdullah, clamp them on an aluminum plate, that will prevent them from overheating. If the input is a 12V supply then you can connect the LEDs in parallel across the output of the first circuit, with a 24V input you will need to connect the LEDs in series and connect their ends with the output of the first circuit. Sorry did not understand what you meant by high side low side current? I measured current using a multimeter, by connecting the same way as when measuring voltage only changing the red wire to the ampere measuring hole. other resistors determine the voltage control parameter of the output. For a maximum operating current limit (after capacitor delay) of 0.8A, do I use R3=0.6/0.8 = 0.75 ohms? an smps converter with 220V to 220V/3amp rating would be required for your application, nothing else looks suitable or safe…. The resistor value will need to be calculated as instructed. This IC was designed for simplicity, using just an LED… Am having 7.5A battery. https://www.mouser.co.uk/datasheet/2/389/tip2955-957163.pdf, I want max 4 amps as I am charging some current sensitive batteries with a 24v LED driver constant Voltage power supply. Please, how can I make a current limiter for 200w solar charger system as float charging. Output Power 12W Max. and eventually get burnt. Any ideas? The datasheet boasts the device to be extremely versatile and efficient as far as voltage and current regulation is concerned, so I don't think the allegations are true, The electronic parts market is filled with duplicate stuffs, and LM338 id no exception, people who complain could have possibly procured a duplicate or a faulty device from the market. Is there any way to implement your circuit to this application. LM317 has internal thermal and short circuit protection so most probably it might be still OK, but if it's a duplicate IC then the results could get seriously affected. I want to used 1 watt LED in 7 no series and 14 no line in parallel total 98 no LED's. In my project I need a 10A current limiter, thus LM196 would be the right choice. Last Updated on November 2, 2020 by Swagatam 214 Comments. Non-Stocked, 240x64 Pixels, STN-GRAY, WHITE LED Backlight, Transflective, 6:00, Wide Temp (-20 to +70C), RoHS, 2x16 Character, 3Vdd, STN-BLUE(-), WHITE LED backlight 3V, Transmissive, 6:00, Wide Temp (-20 to +70c), Serial Interface, 1x10 hard pin, RoHS, 160x128 Pixels, STN-GRAY, WHITE LED backlight, Transflective, 6:00, Wide Temp (-20 to +70c), selectable font size (7x8 Font default), RoHS, Non-stocked: 500pc MOQ, 240x64 Pixels, STN-BLUE, WHITE LED Backlight, Transmissive, 6:00, Wide Temp (-20 to +70C), RoHS, 2x16 Character, 3Vdd, FSTN(+), WHITE LED backlight 3V, Transflective, 6:00, Wide Temp (-20 to +70c), Serial Interface, 1x10 hard pin, RoHS, 128x32 Pixels, 3Vdd, FSTN(+), Red-Green-Blue LED backlights, Transflective, 6:00, Wide Temp (-20 to +70c), SPI I/O, 17 pins, RoHS, 128x32 Pixels, 3Vdd, FSTN(+), WHITE LED backlight 3V, Transflective, 6:00, Wide Temp (-20 to +70c), SPI I/O, 17 pins, RoHS, 160x128 Pixels, STN-BLUE, WHITE LED backlight, Transmissive, 6:00, Wide Temp (-20 to +70c), selectable font size (7x8 Font default), RoHS, Non-Stocked: 500pc MOQ, 240x64 Pixels, FSTN(+), WHITE LED Backlight, Transflective, 6:00, Wide Temp (-20 to +70C), RoHS, 1x8 Character display, STN-Y/G, NO backlight, Reflective, 6:00, Wide Temp (-20 to +70C), CH x CW = 7.1mm x 3.4mm, RoHS, 2x8 Character display, 3.3Vdd, STN-Y/G, NO backlight, Reflective, 6:00, Wide Temp. multiply 1.25 by the amps that must not exceed. Especially with high watt LEds which tend to generate considerable heat, the above parameters become crucial issues. You can set it at any desired threshold current. suppose if my LED panel needs 13.5v and I am having 13.5v dc smps adapter, can I connect the adapter directly to the LED panel or do I need any resistor?? Thus the supply voltage fluctuations have no effect on the current limiting action of the circuit. Even if your battery is rated at 1000 Ah still a 12V load would work without any issues. The inclusion of R2 pull up resistor makes sure that T1 always conducts with a constant current value (I) as set by the following formula. : My power is 12.3V & 3A. Automotive display LED-backlight driver with four 200-mA channels: LP8864S-Q1: Automotive display LED-backlight with four 150-mA channels: LP8866-Q1: Automotive display LED-backlight driver with six 200-mA channels: LP8866S-Q1: Automotive display LED-backlight with six 150-mA channels: TPS7A20 but Led burned due to excess of current so i red about LM338 and i found that it allows 5A current,, all i need is 3A & 3.37V. Hai,In the above current limiting circuit, the output voltage will be equal to input voltage, Am I right??I.e. The formula for determining R1 is given in the article. Making a current controlled LED tubelight. if 13.5v drops down there won't be a problem but it must not rise upto 14V or 15V. I woul be making three of them, one for each color and using the LM317 with a 12V supply.Please guide me accordingly.LED Emitter:(Red, Green, Blue)Wavelength: RED:620-625NM, GREEN:520-530NM, BLUE:460-470NMDC Forward Voltage (VF): RED:6-8V, GREEN:9-12V,BLUE:9-12VDC Forward Currect (IF): 350mA Each Color, Th first design would be more suitable for your requirement…. the dynamo output. Does the value of R1 or the setting of the P1 pot matter? So it is not the current rather heat which destroys an LEd in the absence of cooling. or can you kindly show me another circuit please? Transformer out put current after 10amp bridge rectifier is 7amp.when directly connected to DMM. R = 1.25/5 = 0.25 ohms, wattage = 1.25 x 5 = 6.25 watts. Oh well.Thanks for all your help. arduiplanet Arduino Maroc, Vente en ligne du composants électroniques, Arduino, Raspberry pi, Modules et capteur, Paiement à la livraison ou Paypal Hello again I really want to adjust the current limit a little, so thought to feed T1 with a voltage divider (a pot) of 10k? You can use 3 separate current limiter modules for the 3 lamps…. Fuente Driver Para Led De 8-12W Voltaje De Entrada 85-265Vca. supply is constant because i use SMPS supply. go on experimenting with more number of turns at the output winding by some trial and error until you are able to get 220V across the output winding…. If you do not want to use a mosfet then you must try the second last design. The current controller allows full 2 amp current during “pull-in”. Need ouput of 700mA. Much appreciated. Thankyou… So no need of current limiter circuit. Leelesh, there can be only two reasons behind this issue, either your LM338 is a duplicate or faulty, or your connections are not fully correct. 36 watt LED light,12v .If the above sentence is right,it means no need of current controling curcuit.Am I right? I calculated R1 value to be 169 ohms ( R1=((8.4-0.7)*(110))/5) and R3 to be .12Ohms (R3=0.6/5). Do you think dispensing with or leaving out T2 would work therefore as a current limiter if one uses a pot as a voltage divider on the base of the power transistor instead of T2 etc? Swagatam, i have a need to do DC current limiting on a much larger scale. LM338 or LM196?? which one I can use?? My question is, how do you hook this up to the Arduino ? I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. What can i do? I have connected 30x1w leds….3 leds in a string totally 10 strings…..my input voltage is 12v 5amps…..how should i wire up these led arrays to the input source…..aim of the circuit: led should glow at full brightness, less heat generation. yes Vref is fixed for all input voltages. hello swag i used the above circuit with 30 watt led .all going well but i couldn,t find 0.7ohm 7watt resister.. so i used 2 resisters of ( 0.33ohm 5watt + 0.33ohm 5watt )in series . Yes that’s true only for those devices whose temperature rise affects its current consumption, otherwise current control is not required. I used this supply for 5 1watt ultra bright LED in series along with 6ohm 1 watt resistor. Dave, you can try applying the second last design by upgrading the MOSFET with 5 to 6nos of IRF540 in parallel. If the input is 12v, 1A means, by a suitable resistor of R1, I can get 12v,700mA.And can give the input as 5V, 1A to get 5V, 700mA as output in the above circuit?? i have 12v 5A adapter as input. And, Will the IC LM338 be able to accept that much current to its input prior to limit it's value??????? easy-electronic-circuits.blogspot.in/2012/03/deriving-high-current-from-7805-7812.html. I need your help to limit high amp input. which gets its base bias from a 5 k variable resistor. Comprar. Forgot to tell you that you simply don’t need any special current controller for smaller LEDs with 15mA, 20mA current specs, just a resistor is enough for the job for these low current devices. Dear Satheesh, please refer to the first circuit shown in the above article, you can use the same concept for your LED. thanks for this one but i really don,t get it. Its nice to read your knowledgable blog, I'm a Street Vendor in Delhi have 7 Outlets as of now and in search of a lighting system for the vending counters. How to convert that to 13.5v 700mA DC? Everything okay now, the output is coming 1.2Amps. A specialized current limiter becomes crucial only for those LEDs that are rated with over 100mA current and have the tendency of becoming hot themselves. This chip has some surprising features, such as a charge pump that lets you power a 2-volt LED from a 1.5-volt battery. The approximate voltage across the load (Vload) should be in the region of 16.5 volts, I understand that this may change due to the type of circuit in use. Hi Jennifer, the transistorized circuits shown at the bottom section of the article will easily work with 3V supplies. Your understanding is correct but won’t be as efficient as including T2 would be. Say we had a 24VDC system with capability of 350A continuous. 300Ma. Do you have any tip? Also the LM317 became very hot when I was measuring the current only. I read here somewhere the following sentence :-“If your load is rated at 12V, then the current would have not effect on its functioning because if the load and source voltages are correctly matched, current becomes immaterial. That said, the limiting range and accuracy can be affected depending on the temperature of the transistor. Dear Mr. Swagatam, I would like to make a LED driver circuit which consist 4 nos of 10W LED. how to make it? In your case the bulb is in series with the load so it’s basically acting like a limiting resistor. If the input is a pure DC no other part would be required for the above circuits….. hello. A 12v festoon filament bulb of 15w, (car interior bulb) should have 1 ohm cold and 10 ohms hot (it draws 1 amp normally). ''( Value and wattage ). actually 6 of those led at once. But for the lamps in the series with REC, TAPE MON, etc, I don’t understand how the RC circuits affect the voltage, so I can’t spec the lamp. Or if the current is a constant 1A, the LEDs will glow brightly in 9V also? for 700mA the resistor wattage sould be 1.25 x 0.7 = 0.87 watts or simply 1 watt. Hi Garfield, for 10 watt LEDs the Arduino signals will need to be fed to transistor drivers, and the LEDs will need to be connected across the collectors (for BJT), or drains (for mosfets) and the positive line…this positive line is supposed to come from the above current limiter stage….I hope you got the plan. If the LEDs are 20 mA type then current limiting can be done with series resistors, transistor current limiting is normally required only for power LEDs, with current higher than 100 mA. Can i skip the current limiting section from the above ckt to drive n nos. you can simply feed the 12V at the input of the first circuit, and use the output to power the Arduino lamp. connect around 50 LEDs in series, and make sure to adjust the 10k preset to produce around 170V across emitter/ground of the transistor before attaching the LED series. The resistor is calculated in the following way: Yes, I was not understanding the maths. I have a programmable PSU to deliver the supply voltage, so this can be increased as needed. I have deleted your previous comment to avoid duplication. effective current limiter circuit for your LED, LM317 with Outboard Current Boost Circuit, Illuminating 24 White LEDs from two 9 Volt Cells, https://www.homemade-circuits.com/constant-current-source/, http://www.instructables.com/id/Mood-Lamp-with-Arduino/, https://homemade-circuits.com/2013/06/universal-ic-555-buck-boost-circuit.html, Small Signal Transistor(BJT) and Diode Quick Datasheet. If you have any circuit related query, you may interact through comments, I'll be most happy to help! Is the voltage drop always going to be too large to power LEDs with 3v forward voltage? If they are incandescent lamps then definitely the PNPs are not limiting current, they are probably used as switches. If I use the last circuit, will there be any difference between high side and low side current limiting? I tried to build a simple model in iCircuit, and the current was always the same no matter what bulb characteristics I chose. but ignore and remove everything that's on the right side of the BD139 emitter….rather connect your LED in series across the emitter and ground of the BD139. Hello, I made the first circuit shown here. 7805 will not supply 10 watt at 3.3V so it cannot be used. Hi Vinu,connect 6 ohm 1 watt resistors with each string otherwise your LEDs could burn at 12V. of high power leds of 5W,12v.Will be driving it by pc smps 12v rail. However as i don’t need the voltage at the output to be adjustable (therefore I want to remove the potentiometer) how do I calculate what the required resistances are for R3/R1 replacement? SunFounder is a company focused on STEM education with products like open-source robots, Arduino& Raspberry Pi Kits, Display screens, and smart devices. LM317 will not work, since parallel connection of the LEDs will require 650 x 6 = 3.9 amps. my question is how we can improve illumination & is it required current limiter circuit in above article in this application. sir i used transformer 9-0-9 which draw total 19.1v AC after that is used LM317T for DC supply. I am having 12v 1A DC adapter. Due to this the current increase would get countered and restricted through the load. The series resistor connected with the three LEDs is calculated by using the following formula: R = (supply voltage – Total LED forward voltage) / LED current, R watts = V x A = (12-9.9) x 3 = 2.1 x 3 = 6.3 watts. If an LED is driven with higher current it will tend to get hot beyond tolerance and get destroyed, while conversely if the heat dissipation is not controlled the LED will start drawing more current until it gets destroyed. On the contrary if only a limiter resistor is used it will keep dissipating power at different levels regardless of the over current, and never allow a complete shut down of the supply on over current conditions. Hi Swagatam, Will the circuit work with 3 volts to power standard 3mm 15-20mA LEDs? If it is a current limiter circuit, it should always provide 0.8A whatever the load.Anyway, is my calculations correct??? and if possible Please, where should I connect the ammeter safely so that it works correctly, thank you very much for your attention, I await a reply please through by e-mail to HNF1975@gmail.com. However, remember doing this will heat up the current regulator, so you must take the readings quickly for the necessary calibration. So it seems 24v input would give me 19.7v 3600mA output which was the sweet spot where I could get a max of 70 watt to drive the led. Thank you so much, but I do not completely understand. Seeeduino V4.2 is an Arduino-compatible board, which is based on ATmega328P MCU, Arduino UNO bootloader, and with an ATMEGA16U2 as a UART-to-USB converter. i made a small observation in the second diagram in the smp you wrote 12amp and 5amp, i think the 12 should be voltage value and not current, am i write? It is mandatory for all high watt LEDs.. Firstly, wow, our names are quite similar.Secondly, I plan to connect about 15 pcs of 10w leds (9-12V,1050mA)using a computer PSU (12V,20A), but I hear there's a risk of burning the leds out due to variable current and heat. Even though I kinda got the basic concept of the circuit from the link you provided, I have no clue how to practically apply it, what components do I need to procure? After lots of reading, other web sites indicate that you do not get the voltage out that you put into lm338 as indicated in this post. And to make it compact it is needed to be transformerless. The current increased till it hit 24v and started decreasing above 24v. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. I found winding the input voltage from 20 volts up to 28 volts the output voltage driving the led remained the same at 19.7 volts. Could you point me in the right direction please. Hi Sir,How U??? The idea should to slowly increase the voltage instead of applying it at once. Thanks very prompt. So need a clarification on calculation.And am having another two doubts…Q1:- 1. Select this highest value. Th supply voltage can be increased to approx 24 volts. I have used 32 volt supply 0.36 ohms connected between Vout and adj.I figure this would give me approx. A vintage way is the LM3909, a chip from 1975 that can flash an LED for a year from a single flashlight battery. One user has wrtitten “I designed a current controller using $5 worth of parts that you can get from Radio Shack. We can easily convert the above fixed current limiter into a versatile variable current limiter circuit. Just connect it with your smps, and obtain the required 13.5V across the coil. 400 milliseconds later it falls off to a modest “hold-in” current of 800 milliamps.”. you can use the following software for calculating R1, R2 values precisely: https://www.homemade-circuits.com/lm317-lm338-lm396-calculator-software/. (the 3 connectons on the pot)? i want to use LM317T IC instead mentioned one. I may not have a IRF 540 so the link was for the power nower transistor I will try and use. The working can be understood as follows. The three on-board Grove interface can make your board connect to over 300 Grove modules. The output voltage is quite a bit lower than the input voltage though. Can u tell me what resistor value I can replace with that existing resistor?? Found the datasheet – is there an alternative to the 2N3054 in a more standard small surface mount package? Hello, I am looking to replace some indicator lamps in an old JVC A-X9 amplifier, but there are no specs in the service manual, so I am trying to figure out the circuit diagram. The current passing through the load is required to be limited to 3A and the negative or ground side of the load is required to be connected to the ground or 0 volts. ... 10 LEDs of 1 watt each connected in series which require 33v, 350 mA, 2. A shunt is supposed to short the power supply rails on overload. https://photos.app.goo.gl/ViT82BJekkvEDB9L8, Here are the schematics of the indicator lamp circuits, Yes those are incandescent lamps and don’t require current limiting, you can replace them with individual LED/resistor assembly. I think I am not understanding Vref. Hi, thanks, the following idea should accomplish the intended slow start current limit application: The R3 develops the required switch ON voltage for the BC547 transistor base whenever the current limit exceeds the maximum tolerable threshold. I have used the IC myself plenty of times and have never faced this issue, if this would be the case the manufacturer would have clearly mentioned it in the datasheet. What would you suggest? input current does not matter, neither will the output consumption, it's the input voltage that must not exceed 35V, rest everything is internally protected for these ICs. the controller “see’s” a large inrush current and before the locomotive can move and trips the overload circuit in the controller. I am thinking some sort of an RC network to control a mosfet that gives path to one resistor when first energized, then a path to the second resistor value when the capacitor voltage decays, but not sure how to approach that. I would like to change to LEDs, so I am trying to figure out what the circuit will require for modification. Am using 13.5v smps adaptor. Previously, perhaps the LM317 had shut down due to overheating. yes even with an output short circuit the current should be limited, not sure how it was showing 2.3 amps, anyway it's good to know that it's working now. A good LM338 will produce a guaranteed 5 amps provided the input is rated higher than 5 amps and the IC is mounted on a large heatsink. Your email address will not be published. I am sure something should be connected to limit the current. what is the maximum number of LED's I can use in this circuit all (1 watt). If your current reading is showing the specified 1 amp then the heating of the devices is not an issue, so better confirm the reading by putting the ammeter in series with the LED once again. we get for 12v 2 amp supply R1 = 1.25/2 = 625 ohms and 2.5 watts (3 Watt resistor)and for 12v 1.5 amp supply R1 = 1.25/1.5 = 0.833 ohms and 2 watts for 12v 1 amp supply R1 = 1.25/1.5 = 1.25 ohms and 1.25 watt, Are these calculations correct? I wonder therefore if one uses this as the shunt resistor (on the NPN emitter), and just use one BJT transistor (my Power transistor) I could then have a 10k pot(entiometer) feeding the base between the 24 power supply rails? Thanks sir, please how can I calculate the appropriate resistor value and wattage. Many thanks, from the “0-300V Adjustable MOSFeT Transformer-less Power Supply” Circuit diagram, as directed i will ignore the bridge rectifier (D1) and the reservoir capacitor (C1). I’ve bought a similar current controlled circuit but it’s minimum of 4 volts and I need the smaller battery size. Can you determine the type of bulb from the schematic? So, to power a 12V LED, should I use a minimum of 15V power supply? LM317 is designed for handling currents up to 1.5 amps, LM338 will allow a maximum of 5 amps while LM196 is assigned for generating as high as 10 amps. I don't think a simulation would be necessary, simulators are not always correct, it's better to build the circuit and verify the results using a digital multimeter, that would enable you to understand the design practically, tweak it personally and also confirm the final results. A series resistor could be included as given in the second diagram, however even if it's not included the LEDs would be safe due to R1 which will never allow the current to go beyond the unsafe level. And how to calculate it? Connected two strings in parallel. On a side note, I had some 1n4007 diodes, anyways they can be used? Ashoke, use three 1 ohms in parallel, that will give 0.3 ohms almost. Thankyou. Hai, with reference of ur 12v 1A smps adapter, I found the last resistor which is connected to the output section in my 12v 1A smps adapter. I have 24 volt 5 amp supply & 1 watt LED in series 7 no so is it necessary to use current generator or limiter after supply? can 7805 IC good enough for a cree XML-t6 ( 10watt 3.3V ) Led? ? Swagtam, I’m trying to use the the Darlington Transistor schematic to limit current to 5volts. It may be due to the current limitation of 2A. your power supply is a current generator. I'm Not able to find possible solution to my Problem, would be great if you could help. Hugely helpful. how did you measure the output current? I Don't have electricity available on the streets hence have to rely completely on BattteriesI'm Currentlky using 80 Watts 1 watt LED Strips that operate with 12 V Battery, But want to increase the lighting to around 400 Watts with minimum powerc onsumption of battery Power. A Shunt is normally connected in parallel to the load, not in series. Starting Temp. An LED system is itself the most economical lighting option available to date, it cannot be further modified in any manner for getting more than what its been specified at. The original circuit used incandescent bulbs, not LEDs. say, if i need to drive those led at 10v and 500mA, what i need to do? So finding the sweet spot on the input potentiometer is important to keep things cool and efficient. Make sure to calculate them correctly. Dear sir, Good day to you Kindly help me How do I connect one 10 watts LED through a LM338? My pleasure! Zener is required only for a mosfet not for BJTs. if it's an smps, you can simply do it by changing one of the resistors at the output section of the circuit.open it and show me the picture I'll try to figure out the resistor. At 3 mA each of the LEDs will look very dimly lit. We use cookies to ensure that we give you the best experience on our website. Your email address will not be published. Hi Saqib, all comments are held for moderation without any notice, so they will always reach me, no issues. $135.00. so how can i connect them?. i m looking forward for your reply . Everything will abide by Ohm's law, only the way to understand it could change as per the specifications of the particular component. that’s absolutely correct, but only as long as your LED does not heat up. the 3V drop is due to the generation of heat from the IC and not because of the IC internal circuit, but anyway that means a 3V higher input will be required. I want input voltage to be 230v DC and have 7 x 100w led. and also you may entirely remove the BC547 stage along with all the components connected to its base, Hi Swagatam,LM317 circuit with power supply of 12v 2amp (or 1.5amp? LM338 capable of giving max output of giving 5A. when he connected the fan to the battery he felt that fan wires are getting hot. I you already have a current controlled circuit in your LED system then the above circuit won't be required. Thanks Brian, I think 9 to 12V across gate/source should be enough for most MOSFETs to remain switched ON optimally. Why is that happening? You can try the “Slow Turn ON Output Power Supply” concept presented in the following article, this may probably solve the issue for your application. Your LED burnt due to heat, and thermal runaway. I want to make a 7w bulb using Edison 0.5w,5630 led. yes, if your 13.5V is almost constant and the ambient heat does not rise by too much then a series resistor and optimal heatsinking will be enough for the LEDs. But don't know how to insert LM338 into the software as its not there by default and I can't find any instructions that I understand to insert it.
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