This fully programmable dc electronic load is capable of supporting a maximum of 150 watts of power in any combination of 360 volts and 30 amps. Creating a current source as opposed to current sink for driving a grounded load can be a bit awkward. Im having trouble with a circuit that im working on. A constant current source source can supply a fixed current to a load regardless of input voltage or load change. Simple dual constantcurrent load tests lowcurrent power supplies circuit.
A simple programmable electronic load using the arduino. This circuit provides a constant current load through q1 and q2. Circuitlab is an inbrowser schematic capture and circuit simulation software tool to help you rapidly design and. The ic has been specifically designed for operating high power leds safely by providing a constant current output. Constant current dummy load designs built around the venerable lm324 quad opamp have. The procedure ensures a stabilized voltage and frequency output for the user. Edn circuit provides constantcurrent load for testing. It is this inverse property of a constant power load that is often useful in stability analysis of simulations like those of a switching mode power supply. Below is a capture of my workbook reflecting the same. After exceed this limit drop charging voltage and maintaining maximum charging current. Input voltage regulation from a constant current source provides constant output power to the load. Arduino programmable constant current power resistance. We have to install a heat sink for the transistor, since the transistors work in linear mode and dissipate a lot of heat.
In this post we try to analyze what is constant current source and how it affects a load, or how it may be used with a load correctly for achieving the most efficient results. Im just trying to make a circuit which can give a constant current to a varying load of around 01k and have the current stay constant. You can set a constant current cc, a constant power cp, or a constant resistance cr load by simply typing it in to the arduino serial monitor. Free electrical schematic diagram software drawing. Circuitlab is an inbrowser schematic capture and circuit simulation software tool to help you rapidly design. Starting from the left, we have a pwm signal that will come from an arduino io pin. The lt3741 and lt37411 are fixed frequency synchronous stepdown dcdc controllers designed to accurately regulate the output current at up to 20a. Below is a picture of the supply, mounted into a section of aluminum square tubing. In our previous voltagecontrolled current source tutorial, we have explained how to use an operational amplifier. How is the emitter current kept constant while measuring the output characteristic of a bjt. Or you can test how stable your power supply is with a certain lo. Current source for grounded load schematic circuit diagram.
The simplest constant current load for learning and experimentation. Eagle pcb free electrical schematic diagram software. L200 is a five pin adjustable voltage and current regulator ic. Constant current dummy load designs built around the venerable. A variable load allows you to dynamically set its value according to your current requirements. Build your own adjustable electronic dc load using arduino. Constant voltage drivers are similar, but opposite, with fixed voltages and variable currents. This is a fairly standard constant current driver circuit with zener over protection applied. Simulating a current load in ltspice forum for electronics.
Ys was inspired to come up with the circuit after reading wednesdays re. I have simulated the circuit and it works fine, however, when i am making the actual circuit on the board, it doesnt work anymore. You mention that you need a constant current of 10 ma delivered to a load that can vary from 10 ohms, to 5 k ohms. Constant current led drivers have a fixed current in amperes or milliamperes and a variable voltage. This project is based on the common lm317t regulator, used as a current regulator.
Lt3741 lt37411 datasheet and product info analog devices. A key differentiating factor between led drivers is if they are constantcurrent or constantvoltage operation. Constant current sourceload lm317 the paranoid troll. Q2 collector current is held roughly constant over a wide range of v1. In an actual electronic load, vref is supplied by a digitaltoanalog converter dac. This reference design is a constant current input boost converter for leds which utilizes the lm50202 controller. Admittedly the suggested circuit cheats a little in that the load. To accommodate this i thought of placing a resistor in option c, as shown in the circuit below. Lm317 constant current source is one of the simplest design. R1 n002 n001 100 i1 n002 0 currentp,vn002 v1 n001 0 10 rser1param p10. The circuit attached in a simplified form is intended to pass a constant current 010ma through a load.
Measuring voltage in a constant current source circuit. How to make a constant current source power supply circuit. This electronics kit will provide you with an invaluable instrument for your home lab at a very affordable price. The circuit is ideal for driving led arrays, laser diodes or any other circuit requiring a constant current supply. A while back i built a simple constant current electronic load using an aluminum hdd cooler case as the heatsink. An op amp based current sources output must be able to achieve a voltage level dictated by the constant current value, times the load resistance i x r. Michael dunn is editor in chief at edn with several decades of electronic design experience in. This circuit can also be used as a constant current source. Use a current mirror, which will work down to 100mv or so. Electronic loads are very useful especially if you want to design your own power supply circuits. Perhaps the easiest way to implement constantcurrent led control is with an integrated circuit designed to do precisely thatthere are many such devices to choose from.
Arduino programmable constant current power resistance dummy. The average currentmode controller will maintain inductor current regulation over a wide output voltage range of 0v to vin 2v. The circuit uses a 9v battery and a voltage regulator to. Such a gadget is useful if you want to measure the capacity of chinese liion batteries. Alternatively, this could also be used as an electronic dummy load for testing small power supplies at relatively low current levels. Public circuits tagged constantcurrentsource circuitlab. The design features switch current limiting and input undervoltage lockout. Remote control reuse robots sensors software soldering speakers. Variable dummy load for power supply testing deeptronic. The lm358 cant sink much current at output voltages under 1. A constant power load is designed to dynamically adjust the load current inversely with the load voltage so that the load power is constant, p vi.
In that case, you need to push the forward current out toward the maximum, and to safely do that, you need constantcurrent drive. More project information schematic, parts list, pictures. Solve elec is a free tool used to draw and analyze electrical circuits for alternative and direct current. This pwm signal gets smoothed out by an rc filter to produce a smooth analog voltage. A constant current cc converter regulates current the same way. Hi, im working on designing a lm1085 based voltage regulator that gives out 12v at 3a. I want 100850ma in the output and the circuit was designed for that purpose. Build this power supply circuit to produce a constant current, no matter the load.
What is constant current source homemade circuit projects. Designing a constant current load circuit to discharge a battery. Component schematic reference quantity 10k resistor. An electronic load, also known as a constant current dummy load, is a device design so a power supply can draw a certain amount of current without dissipating too much of heat. In this project we will design an build an electronic dc load which is capable of constant current, constant power and constant resistance. The difference between constant current and constant.
Building a constant currentconstant power electronic load. Voltage causes a current, not the other way around. The basic math behind a cc load is well presented here in a ti application. The lm317 ic is quite useful as a constant current source, works on a wide input voltage range, from 3 v up to 40 v, and cheap too, heres the datasheet. Circuit specialists 150 watt, 360 volt programmable dc electronic load the csi3710a is a programmable bench top electronic dc load with finely adjustable voltage and current inputs. Public circuits, schematics, and circuit simulations on circuitlab tagged ccconstantcurrent. This regulator ic is used to keep the charging voltage constant up to maximum charging current. It doesnt have a true 0v capable output stage, just a constant current source pulldown attached to an ordinary output stage. An adc is used to determine the current through a sense resistor but i also want to measure the voltage on either side of the load. How to design a simple constant currentconstant voltage. In this small project i will show you how to make a simple adjustable constant current load. Figure 1 a tester of aa or aaasized batteries uses constantcurrent load.
The user sets the dac output voltage to yield the desired constantcurent level. Hi, i am building a constant current laser driver using lm317t. Instead, you can use the circuit in figure 1 to produce a constantcurrent load. Constant resistance, constant current and constant power loads. Public circuits, schematics, and circuit simulations on circuitlab tagged constantcurrent source.
I could not find the right switch, so only option bc is illustrated. How to design a simple constant currentconstant voltage buck converter. The post explains a simple electronic load controller or governor circuit which automatically regulates and controls the rotational speed of a hydroelectric generator system by adding or deducting an array of dummy loads. I will also explain how a simple constant current load works and how to build one. In the upperleft of the schematic is a bridge rectifier circuit. Its there so i can power the supply directly from an ac transformer. Circuitlab is an inbrowser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital. An opamp, a mosfet, and a small sense resistor form the constant current circuit. Arduino programmable constant current power resistance dummy load.
This battery charger is based on l200 regulator ic. Glad to see you have arrived on this page to learn how to build a programmable constant direct current dummy load. The basics behind constantcurrent led drive circuitry. Here you can find the schematic for the build and the board design that i created. A source to be tested should be put in place of vtest. Public circuits tagged ccconstantcurrent circuitlab. The software offers the possibility to integrate documentation into the project.
Pmp10523 constant current input boost converter for 2 led. How to make 1 a constant current led driver circuit. The circuit is designed for up to 30v, 5a, and 15w. Below is a shot of my notebook with the circuit diagram, specs and a layout. The circuit includes very few external components and therefore becomes very easy to assemble at home.
Lm2576 constant voltage constant current switching power. So to make a device that provides a constant current no matter the load, we have to use negative feedback and convert the current flowing through our load into a voltage. While it was sufficient for a few amps load under low voltages, it could not handle load much higher than a few dozen watts at least not for a prolonged period of time. If the load current is lower than the desired constant current, the circuit will adjust the gate voltage to reduce rds, and the load current will increase. This load will allow you to draw a set current from any source. The article explains a simple 1 amp constant current led driver circuit using the ic mbi6651 from macroblock. Girish will clearly explain what is cc or how constant current operates. The battery will have just 80% of a full load current.
Lm317 constant current source circuit design circuits diy. The regulated current is set by an analog voltage on the ctrl pins an. Good opportunity to get your sponsor involved do a part b where you put the design into their online pcb software and order a pcb. So i made a super basic constant current load like the one here. Solve elec free electrical schematic diagram software. Everything works fine and i can see a nice clean 12v too but can anyone please help me with simulating this at a current load of 2a. Now, if you have a look at the circuit above, the top of these resistors feed back. Liion capacity test diy constant current load greatscott. This is an operational amplifier based adjustable current source and it uses lm358 in a general voltage follower configuration. Soldering all components except the transistors on to a matrix board is the fastest way to build this circuit, it will be very easy because its. In this blog entry, i describe a constantcurrent lm2576 power supply. The basic math behind a cc load is well presented here in a ti application note in this application a dac is used to set a precise current value, but of course this could equally be a simple pot across vcc to ground. I have used eagle pcb design software to design my pcb. That was a constant current load, not a constant resistance load.