Set the current to the rated current of the power supply. I released a open source hardware kit last month called da pimp which works off the same principle. Arduinoprogrammableconstantcurrentpowerresistanceload. The led5000 is a monolithic buck switching regulator specifically designed to drive long led strings with an input voltage range from 5. What are the minimum design elements required for a useful load. Arduino programmable constant current power resistance dummy load. You can find lots of diy dummy load projects and we wont be talking about commercial ones right now. Therefore, at present maximum 24v, 5a load can be set by this dummy load. This project shows you how to build a simple constant current sink which can be used to simulate a dc dummy load. The cc and cr mode load simulations are useful for testing whether the output voltage of the uut remains stable or regulated under different load conditions. After a bit of work and one board spin i came up with this.
The circuit is quite simple, a voltage follower or buffer using opamp. In november 2014 i began working on a constant current dummy load project. Discharge testing batteries is the only verifiable method the capacity of your batteries and the slb delivers a programmable, constant current load for your testing needs. This is all of the code, datasheets and design files for my instructable. Simple dc dummy load microcontroller project circuit. Array 3721a 400 watt programmable dc electronic load 080v, 040a.
Basically, when you dial in a current level, the electronic load circuitry will draw only that amount of current, regardless of the voltage. Arduino, atmega328p, dummy load, electronic load, encoder, irfp150n, lm324, mcp4921. Users can easily design programs that precisely control all of the load values and time durations for each step of a test sequence. Unlike conventional resistive loads, the dummy load maintains a constant but adjustable load current for voltages in the range of 40 volts. Dc load to constant current mode you may have to press the button twice. It may look like a design off to the board house for production but thatas actually a repurposed pcb. 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. Unfortunately, this kind of high power resistor is expensive and not so flexible getting wide adjustment. This answer is based on a simple opamp dc constantcurrent configuration. Arduino it contains the arduino code that we will be talking about here, within the dummy load folder. May 18, 2016 in other words, a constant current load would draw approx the same amount of current, despite wide variations in the source voltage or other impedances in the circuit. Using a constant current or constant resistance load risks overestimating the capacity of the battery. Using a constantcurrent or constantresistance load risks overestimating the capacity of the battery. It works like the standard dc load that you can find all over the web with an opamp that drives an nchannel mosfet with a current sense resistor but on this one i.
Oct 28, 20 building a dc constant currentpower electric load. The schematic below shows this electronic load design. Our constant current load design is an iteration of a very popular design that you can find all over the internet, possibly either designed or made popular by dave jones from the eevblog. Apr 05, 2015 dummy load primary testing batteries love it great project to build its based on these series video s. An led flashes if this condition is reached and this is done by an opamp. The heatsink i used is a huge piece of aluminum block i got at a local auction. Constant current dummy load home etched, single sided.
Chroma 63200 series electronic loads provide constant current, constant resistance, constant voltage, and constant power modes. Buck current regulators for led stmicroelectronics. Finally, depending on the load current flow through the shunt resistor, a voltage. Constant current power supplies are helpful devices. As per the powerlaw, it will support maximum 7a p i 2 r, but for the safe side, it is wiser to limit the load current maximum of 5a.
Beginner information related to constant current dummy loads. The purpose of project is to build dummy artificial load for testing dc power sources. Variable dummy load for power supply testing deeptronic. A source to be tested should be put in place of vtest. This load will allow you to draw a set current from any source. Nov 03, 2014 the internet and places like the eevblog forum are full of implementations of some variant of this basic mosfet based constant current dummy load. Its pretty simple the positive input terminal of the op amp is connected to a voltage reference and the negative input is connected to a sense resistor. I am beginning an electronics design project to build a constant current load to drive testings for batteries, bench power supplies etc. Glad to see you have arrived on this page to learn how to build a programmable constant direct current dummy load. I have been hard trying to locate some blackonwhite information over the net to get the basics. The first opamp ic1a, is configured as a voltage follower. Simple dummy load for basic testing do it easy with scienceprog. Our design is built using easily obtained components, and we have increased the input voltage from 5v to 9v, which will enable us to fully saturate the gate.
Our electronic load is designed to have the following input and output sections. The design will use a rotary encoder for input entry and. This circuit provides a constant current load through q1 and q2. This circuit can also be used as a constant current source. Feb 08, 20 this constant resistance dummy load has not yet been tested in the real world. Following some inspiration from both dave jones and martin lortons sites, i decided i will build a constant current dummy load. Ac constantcurrent source design electrical engineering. 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. Constant current dummy load designs built around the venerable lm324 quad opamp have become quite popular in the hobbyist community. Nick found out that most diy dummy loads tend to be complicated or unavailable. Ys was inspired to come up with the circuit after reading wednesdays re.
I make a constant current dummy load using a shunt resistor, a mosfet, an opamp, and a few capictors to test battery life and power supply. I have used eagle pcb design software to design my pcb. Mar 08, 20 basic constant current dummy load using an op amp and a bypassing mosfet is very easy to build and had been made quite popular following daves video on eevblog. This is a nice simple circuit, which is easy and cheap to build, and very useful, especially if you want to design power supply circuits. So i decided to design a little variable ac load that would simulate a resistive load and that would also work with dc. This device uses mosfet transistors for power dissipation so it has two advantages over resistive loads.
A while back i built a simple constant current electronic load using an. Another section of the amplifier is configured as a gain amplifier. Jul 02, 20 i bet you face lots of problems in design process where you simply need to test power supply, or led by providingdrawing constant current regardless to voltage change. Arduino based constant current electronic dummy load 120w.
It is used for battery testing, charging and desulfation. A variable load allows you to dynamically set its value according to your current requirements. Arduino programmable constant current power resistance. The basic concept has been around for a long time though, and its essentially an opamp based current source design. Consider it is designed to deliver 10ma for 100 deg f. I also show the pcb design and the new rotary encoder software ive written. Oct 02, 20 a simple adjustable constant current dummy load, with digital readout and usb data logging. The current source portion of the circuit below is very similar to daves design. Thus the circuit is powered by an external 12v supply.
Designing a constant current load circuit to discharge a battery. The constant divisor voltage is altered to get an output signal of 4v at 100w. This constant resistance dummy load has not yet been tested in the real world. Electronics software archives do it easy with scienceprog. Constant current dc load banks with wireless cell monitoring. Dec 25, 2016 in this project we will design an build an electronic dc load which is capable of constant current, constant power and constant resistance. This dc load features constant voltage, constant resistance, constant current and constant power settings, for uniform, repeatable results. Adjustable constant current load circuit wiring diagrams. I happened to have an old aluminum hard disk cooler case collecting dust. This load can also be set to a constant resistance or a constant pow.
Up to nine separate ten step programs can be internally stored in the array. In this project we will design an build an electronic dc load which is capable of constant current, constant power and constant resistance. That was a constant current load, not a constant resistance load. And until now ive always used just a bare wirewound resistor with some banana plugs as a test load. This is the last installment of the constant current dummy load project. In radio a dummy antenna is connected to the output of a radio transmitter and electrically simulates an antenna, to allow the transmitter to be adjusted and tested without radiating radio waves. Ac and dc dummy load all the electronics thats fit to build.
Arduino programmable constant current power resistance dummy. Assembled variable dummy load to test real capacity of a power supply, we need a load with variable current consumption. Dave grabs a few junkbox parts and builds a useful constant current load for switch mode power supply, battery testing, and other. It can help you test cheap dcdc converters to see if they really put out the amount of current as advertised. If we have high power variable resistor such as tapped wirewound resistor, we can directly connect this resistor and make some measurement. Constant power load needs only a few parts electronic design. I bet you face lots of problems in design process where you simply need to test power supply, or led by providingdrawing constant current regardless to voltage change. Building a constant currentconstant power electronic load. This electronics kit will provide you with an invaluable instrument for your home lab at a very affordable price. Oa1 output will quickly rise, turning on q1, causing current to flow through the load, q1 and r1. Here are some pictures showing the construction of this electronic load. Inspired by a design he saw on the eevblog, george graves put together this constant current dummy load.
The circuit uses two opamps to set the constant current. Home brew dummy loads category is a curation of 30 web resources on, building a rf dummy load, qrp power meter and dummy load, rf dummy load. Problem with constant current dummy load design page 1. Starting from the left, we have a pwm signal that will come from an arduino io pin. Arduinoprogrammable constant current powerresistance load. Oct 24, 20 constant power mode is achieved by calculating the desired set current via the measured load voltage.
I decided i wanted one because i work with a lot of battery powered designs and itd be nice to have a simple way of testing a battery or power supply in terms of capability, capacity, and heat. This pwm signal gets smoothed out by an rc filter to produce a smooth analog voltage. Electronic load controller elc circuit homemade circuit. The basic math behind a cc load is well presented here in a ti application note. Simple dual constantcurrent load tests lowcurrent power supplies. Constant current dc load banks with wireless cell monitoring eagle eyes slbseries dc load banks are designed for user ease of use, portability, and versatility in mind. Building a dc constant currentpower electric load hackaday. A dummy load is a device used to simulate an electrical load, usually for testing purposes. Build your own adjustable electronic dc load using arduino.
1596 708 141 296 1409 1401 862 1336 437 792 82 720 344 17 905 1446 1263 120 1326 1074 260 1241 1323 866 869 734 1081 869 1371 1376 339 1176 814