If you do choose to power this circuit via 12V, ... None the less, we wanted to remove other potential sources of this ripple from the equation and swapped the Dummy Load for a 4.7Ω 100W resistor. Most ATX-Bench supply videos I have seen they use those ceramic resistors for loads. ATX Power Supply. Could an extraterrestrial plant survive inside of a meteor as it enters a planet's atmosphere? MathJax reference. If I am not mistaken such power supplies should have enough internal load to make PSU start. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. rev 2020.12.18.38240, The best answers are voted up and rise to the top, Electrical Engineering Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us. Dummy load in place. One of the important things to do when converting an ATX power supply is to include a “dummy load” resistor. ... (black) wire to attach to the power resistor that I’m using as a load. What makes representing qubits in a 3D real vector space possible? To implement a variable dummy load, a variable voltage regulator LM317 connected as shown in the following diagram is used. How to use a variable dummy load for power supply testing? Allow bash script to be run as root, but not sudo. Is it wise to keep some savings in a cash account to protect against a long term market crash? @Anonymous the resistor shown in above pic connected to the supply is a 10 Ohm resistor. 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. Is this resistor sufficient as dummy load in an ATX 250W Dell PSU? what I actually want to supply with power) and switch off the dummy load with a transistor when it is not needed. Did the actors in All Creatures Great and Small actually have their hands in the animals? I have attached a 20 Ohm resistor to my Dell PSU on the 5V rail since its a 2004 PSU and most of the current is on the +3.3V & +5V rail. Without a load, it may shut down. Now we have 3 different Values for one Instruction. Unfortunately, this kind of high power resistor is expensive and not so flexible getting wide adjustment range. Here is a simple solution using power transistor. How credible are the rumors that the NSA has compromised IPSec? Maybe. Why does the Indian PSLV rocket have tiny boosters? The voltage regulation limits shall be maintained under continuous operation I had to put a load to make it works, I used a resistor 10ohms 25W. 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 to the different voltage outputs. An artificial load just wastes electricity and creates unnecessary heat. I would just like to know wich one of the 3 is right. You should not need external load (unless practice shows otherwise). In one case, the load had to be applied to the 5v standby wire (purple) to ground rather than directly to the 5v rail to ground before the power supply would function properly. Why does wprintf transliterate Russian text in Unicode into Latin on Linux? Is it ethical for students to be required to consent to their final course projects being publicly shared? Magic smoke released from DIY PSU… but why? I was saying that I have only a 1 ohm 5W rectangular ceramic resistor. 500ma). I have attached a picture below for better idea.Thanks in advance everyone. It only takes a minute to sign up. Connecting a 4.7 ohms 10 W resistor, an old CD drive or a 12 V light bulb (into the 5 V rail, see picture) are well proven methods to generate this "dummy" load. Use MathJax to format equations. Add in a variable resistor (~10K) for test. Hook up the supply as in the previous test and slowly increase the resistance from zero, while monitoring the voltage. In the production version we include the resistor but don't solder it because most will never need it. The first three show increasing 12V load with the recommended "dummy" 5V load of a 10 ohm 10W power resistor (i.e. Pete says: March 22, 2013 at 8:28 am. Make a dummy load for a lower voltage DC power supply. In our experience most ATX supplies don't require a significant load on the 5 volt rail to start. I’ve found a collection of Power supply schematics. The no-load output voltage for my appliance is not critical. Power Supply Dummy Load. From what I read I assume(d) that a load is actually required for most ATX PSUs to prevent damage. I added a dummy load resistor because I have in many videos and websites people mention that without a dummy load the ATX output will be unstable. Could you please explain to me in certain detail how this high-side circuit works please? And that is the dummy load. I am planning on converting an ATX PSU into a lab bench power supply, and I've seen plenty of videos and read numerous articles about how easy it is. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. If I understand what you're asking. The first step in the process is to open up the ATX power supply and identify a few key connections as well as determine what voltages the power supply currently generates. Don't forget to cover it with some tape, and place the resistor in the power supply case. Why would merpeople let people ride them? IMHO, ditch the diodes and use a power resistor as your dummy load. I see what you mean. en.wikipedia.org/wiki/Power_supply_unit_(computer)#Testing, Podcast Episode 299: It’s hard to get hacked worse than this, ATX PSU +12V outputs connected in parallel, Charging a bank of batteries in series with a resistor, DIY ATX PSU turns off when attaching load on 12V rail. So instead I decided to make this project. Now I'm more confused than before :) Many sources (like. I understand all of it, except one thing that noone describes fairly well. If you want to follow that advice, use a small power resistor. What would happen if a 10-kg cube of iron, at a temperature close to 0 kelvin, suddenly appeared in your living room? There is a footprint for a 9 Watt 10ohm load resistor on the 5 volt rail. From what I know the Diodes had ideally zero resistence (almost zero) so it will be like a short circuit. I dont a have 10 or 20 ohm 5W one in my posession now. I have a new 500 W ATX power supply with a 30 A 5V rail that I am going to use to power 300 smart RGB LED Christmas lights for my tree this year. I was saying that I have only a 1 ohm 5W rectangular ceramic resistor. The power supply is an Antec Basiq BP500U. This kind of dummy load is widely used in testing power supply. Depending on your power supply, the power resistor can become hot so make sure to use a heat sink and enough air flow to dissipate the heat. If the supply shuts down before +13.8 the high voltage protection circuits may be activated. I have a attached a poorly drawn schematic of what I plan to do. Is it ethical for students to be required to consent to their final course projects being publicly shared? Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. To learn more, see our tips on writing great answers. Attach wires to allow addition of resistance. I tied the load wire to ground, and everything works well. What is the fundamental difference between an AI model and a function? The first line represents the 12V load from motors only. Some ATX PSUs will supply power to the outputs without a dummy load resistor. PCB picture . It only takes a minute to sign up. Some older ATX supplies won't start without some sort of load. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. measured at the load end of the output connectors under all line, load, and environmental Use MathJax to format equations. Finally, I fastened the front … rev 2020.12.18.38240, The best answers are voted up and rise to the top, Electrical Engineering Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us. If your supply doesn’t require a 5-volt load on startup you can eliminate this. Increase up to 13.8V if possible. Even so, it may or may not be stable. … ... Well I could use a resistor but I didn't have many power resistors and when you start testing higher voltages and currents the resistors get really big! PCB is exactly the one shown in that schematic collection page (simply search for text “2003”). SF short story about body-hopping alien hunted by cop. I think it can be useful. SPF record -- why do we use `+a` alongside `+mx`? Due to its internal design, this voltage regulator has a voltage of 1.25 volts between its output terminals (Out) and adjustment terminals (Adj). Now solder Red and Black Wire across it. conditions. I added a dummy load resistor because I have in many videos and websites people mention that without a dummy load the ATX output will be unstable. As I understand all of it, except one thing that noone describes fairly well is... The power supply to drive a 12V DC motor usually is put on the 5 V rail usually cuts,... 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