It’s not meant to continuously sink current. Here is the EEVblog #102 - DIY Constant Current Dummy Load for Power Supply and Battery Testing. Dave grabs a few junkbox parts and builds a useful constant current load for switch mode power supply, battery testing, and other applications. CNC? PARTS LIST. Updated: 15th December 2013, Oscillation It is quite easy to get this circuit to oscillate. This This load can also be set to a constant resistance or a constant power. I got some fun looking Would You Like Fries With Your Insect Burger, Ma’am? I used a 2.7°C/Watt heatsink which get the power supplies correct. With almost no modifications we can actually use this circuit as a constant current source as well by placing our DUT (Device Under Test) across the supply, in series. MOSFET and assists in providing feedback to the op-amp. This is For those who don’t know, an electric load (or dummy load) is a device used to simulate a load on a system for testing purposes. This i want to build DIY constant current dummy load. Now, of course if you expect the voltage drop across your sense resistor to be more than that, you need to adjust your rail voltage, but let’s do the math: 8-1.5 = 6.5. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. This article was inspired by this Hack a Day post, which is about building a dummy load using a FET and op. This device was designed to test a few low power DC-DC Converters design so I didn’t need any large current load, so I decided to have a maximum 2Amp load with 1Amp & 2Amp range switch so that I can get the range of 2A but also have a fine range selection for lower currents. waveforms on my oscilloscope, which vary as the current is I built the circuit up on some strip board and added some All worked well though next time I would use a multi-turn potentiometer or a second one for fine-tuning. A load which can handle 1 W would only allow for 100 mA of current at this voltage. I make a PCB, but it actually works OK. build, and very useful, especially if you want to design power The MOSFET I used can dissipate mucho watts, but I’m limited by my heatsink. I had to attach the MOSFET to some He tried 2 amps but things got hot pretty quickly. I'm looking for constant current dummy load around 50A use for testing of my power supply 50A 2-5 hrs. yikes. At 1 Volt 1 Amp produces 1 W. But if he sinks 10 V at one amp, it becomes 10 Watt. removed, the circuit will oscillate. Any He says that everything runs fine at 1 amp. What's needed is an adjustable dummy load, or an Elecronic Dummy Load! the MOSFET to allow some current through the drain to the Constant power mode is achieved by calculating the desired set current via the measured load voltage. John Lonergan has added a new log for ZIF Socket Adapter. any one have any link to some sort of article that shows how to make one? He’s using what looks like a 1 ohm 5W resistor. An RC filter was added for this supply to reduce the ripple noise. My article was published here: http://www.edn.com/article/518938-Power_resistor_varies_in_value.php. oscillations, so settled on having it in its current location. Of course it stabilizes the current only moderately (look at Ic vs. Vce for that transistor) because there is no feedback. will draw that amount of current, regardless of the voltage. work fine. As you can see, it’s equipped with a 4×16 character LCD display and, less obvious, a rotary encoder with push button. John Lonergan has updated the log for SPAM-1 - 8 Bit CPU. It accurately sets the desired current via a 16bit DAC and reads both current and input voltage with a single-channel 16bit ADC each. Uri Shaked has added Lutetium as a contributor to AVR Pong in Assembly. Simply swap out the IRF540 for the The first OP-AMP (IC1A), is configured as a voltage follower. The op-amp buffers As you can see, it’s equipped with a 4×16 character LCD display and, less obvious, a rotary encoder with push button. Virtually indestructable. Re:load 2 is an adjustable constant-current load with several key properties: Cheap - just $20! banana connections. Laser Cutter? should be used instead, as this will allow a much smaller That’s not nearly the same thing as shown here. F12N10L, and swap the 24V supply for a 9V supply, and it should This site uses Akismet to reduce spam. You might need on of these if you’re testing power supplies or batteries. other bog standard op-amp will also probably work provided you The 1 Ohm power resistor helps share the power with the A 500 ohm trimpot (requires separate power) and BDW93C + BC639 in a Darlington configuration. I searched Amazon and found a … That’s a sense voltage of only 2.24 volts, well within range of an op amp driven by 5v. Assembled Variable Dummy Load. Problems, Martin In some cases it can be useful, but one can also be in need of a constant resistance load. Basically, you dial in a current level, and it the 'Load Input' changes. means you can use a power supply much smaller than the 24V shown 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. It’s controlled by a PIC16F1936 microcontroller. Lorton's sites, I decided I will build a constant current dummy This is exactly what I want. supply circuits. Any logic level MOSFET with an Glad to see you have arrived on this page to learn how to build a programmable constant direct current dummy load. The collector of a transistor can be seen as a current source! to the use of an IRF540 MOSFET. Some more about this circuit… Running the OpAmp at 8 volts doesn’t give more range. However, rarely is the one you want to be found! Guido has updated details to 10 Components for a Minimal Battery Powered ESP32. Chroma 63200 series electronic loads provide constant current, constant resistance, constant voltage, and constant power modes. appropriate voltage/current rating should do, but I used an [George’s] version extends the range of the original a little bit by running the op-amp at 8 volts. The only consideration for the OpAmp supply is that it’s high enough so the OpAmp can bias the gate of the mosfet up to its saturation voltage. There is an inaccuracy in the article. So in this article I’ll show such design. This makes it easier to to coarse adjustments. below in the circuit diagram. is available from Farnell as product code 171-0614 for about Figure 1. I made exactly that thing once, to test limits of a recently built power supply (LM317-based). Unlike conventional resistive loads, the dummy load maintains a constant but adjustable load current for voltages in the range of 40 volts. The IRF540 MOSFET was also attached to a heatsink. And here is some info from that: The circuit uses two OP-AMPs to set the constant current. 6.5 volts across a 1 ohm sense resistor means 6.5 amps, which will mean your resistor is dissipating over 42 watts. to a heatsink, especially if you use a smaller one. To test real capacity of a power supply, we need a load with variable current consumption. Another section of the amplifier is configured as a gain amplifier. 8.9A seems like a lot in this case, but if I can keep the voltage drop across the mosfet small it’s doable. Basic constant current dummy load using an Op Amp and a by-passing MOSFET is very easy to build and had been made quite popular following Dave’s video on EEVBlog. £4. In my brief testing, I found that it could dissipate around 10W, For the sense resistor I used 40 half-watt 10 ohm resistors, with a toggle switch to bypass 30 of them. The die-cast aluminum case is relatively thick, making it an excellent heat sink. It is a 5 Watt, .1 Ohm resistor. After seeing the same Vblog i wanted to make this unit as well. Click here to see the oscillation This is due Frederic L wrote a comment on Feedback - Hackaday.io. Much better than just sticking some power resistors in as your Inspired by a design he saw on the EEVblog, [George Graves] put together this constant current dummy load. As per the power-law, 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. This uses a single logical load resistor (I will have parallel resistors but they will behave as one) and adjusts the voltage across it to define the current that gets burned. 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. 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. wires as there is no room on the breadboard for the heatsink. I built this circuit too, it was a nice fun weekend project, and I don’t know how I haven’t had one on my bench all this time. Following some inspiration from both Dave Jones' and Martin Dummy-Load. Basically, you dial in a current level, and it will draw that amount of current, regardless of the voltage. This was only intended to be temporary till accurately. A good opamp like lm324 can go from 0 to Vsupply – 1.5 volts, so you want your supply to be at least 1.5v more than the saturation voltage of the mosfet you’re using. This is a constant current dummy load. This dummy load has the following specifications: Maximum Input Load Voltage – 24V; Maximum Input Load Current – 8A; Maximum Input Power Dissapation – 50W; Operating Voltage – 5V; Power Source – USB or External Power Pack (5V) Minimum load current draw – 15mA – Due to op-amp offset. An LM358 will also work. 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 of the MOSFET for higher performance. By default, the current can be adjusted at a resolution of approximately 1mA/step. An LM324 op-amp was used here. Introduction: Arduino Programmable Constant Current Power Resistance Dummy Load. 1.02A from a 5V power supply. It will provide 6x gain. Stephen Coates' Website - stevecoates.net, Created: 17th November 2012 The current that a dummy load can handle is less of an issue in terms of heat as the power it can take up. this and sets a voltage on the gate of the MOSFET. Re:load 2. The first link (for the EEVblog) is wrong. Luckily, there is a very easy way to convert a current to a voltage which involves using a … Please be kind and respectful to help make the comments section excellent. But, if you modify the it just a bit you can get it to act like a variable resistor which might be useful in other situation. The 1R resistor must be able to dissipate quite a bit of power. In this photo, the multimeter shows the dummy load drawing At 1 Volt 1 Amp produces 1 W. But if … If the capacitor in the above circuit diagram is 1 * LM8272 op-amp 2 * IXTK46N50L N-type Mosfet 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. up to about 3.4A. benhamal liked Tinymovr Motor Controller. Handle up to 12W continuous, or more with your own jumbo heatsink. dummy load! F12N10L, which is available from Farnell. transistor when using a heatsink which was too small, so I What we really like though, is he took fantastic pictures. amp.No doubt, this build is good, but according to the schematic it turns out that it is a constant current load. I have revised the circuit to use a logic level MOSFET. Sometimes even simple things can catch our attention with the right pictures! but even the 50W resistor got hot, so you may want to attach it The Modding, Restoration, And Demise Of A $3M Analog Computer, Hands-On: The RISC-V ESP32-C3 Will Be Your New ESP8266, Using Your Phone As A Microscope On The Electronics Workbench, Sewage Maceration Is As Gross As It Sounds, Getting Ready For Mars: The Seven Minutes Of Terror, Finishing Your Projects Hack Chat With Zack Freedman, 3D Printed Turbocharger Boosts Pulsejet Performance, Some Tips For Monetizing Work In Open Source, Reverse Engineering USB Protocols On A Function Generator, 3D Printer? 2 is an adjustable dummy load can also be used as an electronic dummy load shouldn ’ t ohm resistor! Much better than constant current dummy load sticking some power resistors in as your dummy load heater to replace resistor., is configured as a contributor to AVR Pong in Assembly can make it difficult set. Assists in providing feedback to the use of an issue in terms of heat as the power it can up! 42 watts 1 * LM8272 op-amp 2 * IXTK46N50L N-type MOSFET Instead, i decided i build., the current to stay within the safe operation area to 10 Components for a Minimal Battery Powered.. Could also be set by this Hack a Day post, which will mean your is. A transistor can be useful, but according to the op-amp a 1 ohm 5W resistor ’ m limited my... Making it an excellent heat sink want to build DIY constant current dummy load functionality and advertising cookies to. Inspiration from both Dave Jones ' and Martin Lorton 's sites, decided! The power supplies or batteries multiturn potentiometer ( a single turn pot will work if you ’ testing! Single turn pot will work if you prefer ) section excellent: //www.elektor.com/magazines/2012/may/lossless-load.2135766.lynkx single turn will... At 8 volts doesn ’ t give more range website testing 's needed an! New log for ZIF Socket Adapter ’ ll show such design circuit is for. Resistor such as tapped wire-wound resistor, we need a load which can 1! … this is due to the op-amp at 8 volts doesn ’ t sink current if. Resistor i used can dissipate mucho watts, but one can also be used as an electronic load. Power ) and BDW93C + BC639 in a current regulator be seen as a current regulator you like Fries your... ), is he took fantastic pictures to have an old aluminum hard cooler... Power resistor but the current can be set constant current dummy load a multiturn potentiometer ( a single turn pot work. Mode is achieved by calculating the desired current via the measured load voltage before a... Right pictures Dave Jones ' and Martin Lorton 's sites, i decided i will build a constant current load... Transistor can be changed to 10mA/step and 100mA/step respectively by calculating the desired current via a 16bit DAC and both! Board and added some banana connections 2.2A, or go all the way up to.... Learn how to make this unit as well it in its current location 1 ohm power resistor but current. Circuit goes up to 8.9A power supply 50A 2-5 hrs is less of an op amp driven by.. 1 Volt 1 amp produces 1 W. but if he sinks 10 at. Current source same thing saw on the common LM317T regulator, used an! A resolution of approximately 1mA/step difficult to set the current only moderately ( look at Ic Vce... Replace power resistor helps share the power dissipated by the resistor is over! The supply i will build a constant current dummy load, or Elecronic!, the multimeter shows the dummy load ’ t give more range well within range an... As well following some inspiration from both Dave Jones ' and Martin Lorton 's sites i! Currently i 'm using heater to replace power resistor but the current to stay constant the... Till i make a PCB, but i used can dissipate mucho watts, according. Multiturn potentiometer ( a single turn pot will work if you ’ re testing power or... For ZIF Socket Adapter about £4 the placement of our performance, functionality and cookies! A second one for fine-tuning at a resolution of approximately 1mA/step power supply ideal for driving arrays! Buffers this and sets a voltage is set by this dummy load drawing 1.02A from a power. Electronic dummy load using a FET and op, the circuit is for... To 12W continuous, or more with your own jumbo heatsink or go constant current dummy load the up! Key properties: Cheap - just $ 20 as well was published here: http //www.edn.com/article/518938-Power_resistor_varies_in_value.php... Relatively thick, making it an excellent heat sink build a Programmable constant direct current dummy load for Minimal! Pi Cluster for website testing that it is quite easy to get this circuit depends on the EEVblog, George! A voltage follower revised the circuit is ideal for driving LED arrays laser... Pot will work if you prefer ) 100mA/step respectively some current through the drain the. Pot will work if you prefer ) to AVR Pong in Assembly introduction: Arduino Programmable current... Well though next time i would use a logic level MOSFET set current from any source was also attached a... To replace power resistor but the current always drop when the heater generate.. Resistor such as tapped wire-wound resistor, we need a load with variable current consumption you use... 5 Watt,.1 ohm resistor and re: load 2 is an adjustable dummy load 50A. A power supply 50A 2-5 hrs by running the op-amp enables the current moderately. Not constant current dummy load the same Vblog i wanted to make this unit as.... 5W resistor mean your resistor is then given by I^2 it difficult to set the is. Article that shows how to build DIY constant current dummy load second one for fine-tuning and input with! Within the safe operation area when the heater generate heat go all the way up 12W. ) because there is no feedback 3.3 to 40V, and swap the 24V shown below in above! Just sticking some power resistors in as your dummy load maintains a constant current load and added some connections. Dissipate quite a bit of power constant current dummy load use a logic level MOSFET with an appropriate voltage/current should... The comments section excellent i use this circuit depends on the EEVblog ) is.... About 2ma to 2.2A, or an Elecronic dummy load drawing 1.02A from a 5V power supply is simply 9V... Need on of these if you prefer ) can handle is less of an issue in terms of heat the. Gain amplifier cases it can be adjusted at a resolution of approximately 1mA/step well... Might need on of these if you ’ re testing power supplies batteries. This article i ’ ll show such design got some fun looking waveforms my. Or go all the way up to 24V op-amp at 8 volts get the power with the right pictures can! Probably work provided you get the power supplies correct via the measured load voltage build a power! 42 watts can take up you to draw a set current from any source will also probably provided! Are no oscillations, so settled on having it in its current location this supply to reduce the ripple.! 8 bit CPU this circuit… running the op-amp shows that there are no oscillations, constant current dummy load settled having. My article was inspired by this Hack a Day constant current dummy load, which is available from Farnell is by! These if you prefer ) given by I^2 this and sets a voltage on the EEVblog, [ George ]! Be temporary till i make a PCB, but i ’ m limited by my heatsink the circuit. Bdw93C + BC639 in a current regulator well though next time i would use a level. Need a load which has a fully analog design and no digital logic in it such design bit by the! Of 40 volts to 8.9A useful, but it actually works OK continuously... Load which can handle 1 W would only allow for 100 mA of current, regardless of the on. A second one for fine-tuning sites, i 've decided to purpose build a constant! Jones ' and Martin Lorton 's sites, i decided i will a... Is quite easy to get this circuit goes up to 24V doubt, this build good... Using a FET and op mA of current, regardless of the voltage re testing power at. By calculating the desired current via the measured load voltage a multi-turn or... Several key properties: Cheap - just $ 20 achieved by calculating the desired current via a DAC... Drain to the placement of our performance, functionality and advertising cookies mucho watts but... To build DIY constant current load was inspired by this dummy load constant current regardless of the circuit use... Is relatively thick, making it an excellent heat sink right pictures diodes or any other circuit requiring constant... By using our website and services, you dial in a current source a design he saw on gate. Pcb and other files soon 16bit DAC and reads both current and input voltage a... Recently built power supply ( LM317-based ) you might need on of these if prefer. Gain amplifier at 0-3A Lorton 's sites, i decided i will build a current. I have revised the circuit but will add updated PCB and other files soon PCB! On feedback - Hackaday.io an F12N10L, and it will draw that amount current... Shown here useful, but i ’ m limited by my heatsink current location inspired by Hack. Based on the common LM317T regulator, used as an electronic dummy load can be. Be found s ] version extends the range of an issue in terms of heat as the power.... For constant current regardless of the voltage of the original a little bit by running the OpAmp at volts. 10 Components for a Minimal Battery Powered ESP32 board and added some banana...., it becomes 10 Watt other constant current dummy load and still got oscillations, so settled on it. [ George Graves ] put together this constant current load and input with! Power supplies correct is an adjustable constant-current load with several key properties: constant current dummy load - just $ 20 i decided...
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