I want to make something that will properly load all lines so I can measure voltages and ripple of old power supplies and on that way determine if they are stable, accurate and have ripple under ATX standards. 1.1. From 0kw to the max, any load combination is achievable. A good design of dummy load can be found in the project A Switched Dummy Load, also in this book. The current of dummy load freewheels through the closed contactor. A very small low-power dummy load such as a ceramic power resistor or 10-watt light bulb can be attached to the supply to allow it to run with no primary load attached. My old boss built a 6kW dummy load for testing a generator by winding galvanised fence wire around a 4inch asbestos drain pipe in the early 1960s. Joined: 23 May 2013 2:53 am Posts: 47 Location: Yorktown, VA I'm modifying an existing circuit, a tube-based guitar amp, and I'll be using a new transformer, a new level of desired B+ voltage, and a totally new rectifier arrangement. 4. The Dummy Load Unit is an active power supply load that can be adjusted with a multi-turn control. Configurable specifications: total power rating, load duration, memory interval, time etc. Follow. EEVblog #102 - DIY Constant Current Dummy Load for Power Supply and Battery Testing. 2. 3. we set the target constant current 59mA(about 60mA), for a while the load stabilized, and see the sample I/V, we find that now the current trough the dummy is 62mA, but the voltage is drop to 4.731V !! Load step resolution is … Such device is called a dummy load. This dummy-load circuit has been in use at Maxim for more than 10 years (see the figure).It's useful for testing power supplies and power amplifiers as well as drivers for LEDs, relays, and solenoids. Some ATX PSUs will supply power to the outputs without a dummy load resistor. Kaixiang has more than 20 years of professional experience in testing and commissioning of generators, batteries and UPS. How to make dummy load for ATX power supply 300W Is there any schematic to build power supply load to test 300W power supplies? For this reason, it is best to provide a dummy load resistor to one of the power rails to ensure a stable, continuous supply of power … A load bank (dummy load) is a stationary or mobile piece of equipment that provides operator-adjustable electrical resistance or resistance and reactance to simulate the actual electrical load the genset is intended to power. Reading on the internet indicates the SMPS may burn itself out if powered up without a load. Working mode: Load step control Total testing capacity ranges from 0kw to the max consisting of 10kw, 20kw, 50kw, 100kw load setting switches plus a 0-10kw fine-tuning knob. EEVblog August 1, 2010 EEVblog, EEVblog - Podcast Comments Off on EEVblog #102 – DIY Constant Current Dummy Load for Power Supply and Battery Testing 43,607 Views Dave grabs a few junkbox parts and builds a useful constant current load for switch mode power supply, battery testing, and other applications. These are nice metal-tubbed power resistors made by Milwaukie resistor. Now the dummy load just support CC (Constant Current) mode now. Load banks are connected to electrical power supplies to simulate the supply's intended electrical load for testing purposes. It means that this USB power adaptor can not supply 62mA at 5V but just can at 4.7V! Dave grabs a few junkbox parts and builds a useful constant current load for switch mode power supply, battery testing, and other applications. Post subject: Choosing a dummy load for testing a new power supply design. For example, a power supply that’s rated for 10 volts and 1 amp needs a resistor of at least 10 volts times 1 amp = 10 watts. Hi I'm reading up all the various youtube videos, websites, etc on converting a surplus PC ATX power supply to be a benchtop supply, and all of them note the ATX requirement for a dummy load between 5V and ground or the PSU will turn off. I bet you face lots of problems in design process where you simply need to test power supply, or LED by providing/drawing constant current regardless to voltage change. I think I would find a "dummy load" for testing power supplies useful. For \$ 10 \Omega\$ \$ 10W \$ load: Posted: 28 Jul 2014 10:37 pm . I used a "selector switch" from Idec to allow selection of 4 ohms (two resistors in parallel), 8 ohms (4 resistors in series-parallel), or 12 ohms (one in series with two in parallel). Any loop instability will be uncovered this way. If you are testing various power supplies (switching or traditional), surely you will need a test load, whose current consumption can be regulated. A nice dummy load. Testing reports of "load at permanent power rating", "load at certain power rating", "Sudden increment or … Testing Power Converters Using a Liquid-Rheostat Dummy Load Described here is an electrochemical cell that can be a very effective dummy load for testing power converters. The SMPS lay unused for nearly 10 years now. You can find lots of DIY dummy load projects and we won’t be talking about commercial ones right now. Such a dummy load can help you to find out exactly the current threshold, where the ripple starts to occur, the current limit kicks in, the output voltage start to fall or the electronic fuse turns off. It has great practical benefits, such as simple and low-cost construction, reasonable power dissipation, negligible leakage inductance, and … This variable dummy load is helpful in power supply testing by providing virtual load which can be adjusted to draw certain current. 60KW DC Dummy Load Bank For Power Supply Testing . Testing power or external utility power supply for fans. ATX supply needs a minimum load on its output to regulate. Load banks are devices with dummy loads, specifically designed for battery discharge testing or testing of power sources such as battery chargers, uninterrupted power system or generators. EEVblog. The DLU is a building block that can be replicated to any level as required. The collector of an NPN transistor behaves like a current sink so it has a very high internal resistance. Depending on what the switcher chip in the supply is , the supply can shut itself down if the output voltage goes high. \$ 12V \times 8A = 96W\$ so I guess it should be good for about 80-85W . The power supply charges the dummy load to a certain current until flattop, then close the contactor to short and turn of the SCCPS. I don't want to spend big on a programmable load, something basic, even quite Heath Robinson would be adequate, but I would like to dissipate 60V at 50 Amps for say an hour, so water cooling looks promising. To make the dummy load useful for testing modern amplifiers,it is necessary to provide a choice of at least two load impedances (8 Ω and 4 Ω), and preferably 6 Ω as well, which can cope with power levels comfortably above 100 W for the 8Ω load and somewhat higher for the two lower impedances. If you dont have a load, the output voltages will rise above their nominal values. An RF power meter and frequency counter will also be useful, although if your receiver has a digital frequency readout and S-meter, the latter two items are not really necessary. Select a dummy load based on the power supply’s specifications by using Ohm’s Law. 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