tane Posted June 26, 2020 Share Posted June 26, 2020 Recently I had to change my 5.0V power supply. I found one 5V lying around (by the way, made in China) and after turn on the Atari (by the way, my arrowhead machine), immediately I realized the colors were not the same, it was a bluish tonality. After that, I was heavily worried for some minutes, and then I tested the voltage resulting in 5.34V. So I was thinking what about to install a voltage regulator. Making a research, I though it should have been easily to find an option, since that many devices use 5V. Even thought there are several regulators, not too many accomplish the required features: Step-up (boost converter) to 5V Step-down (buck) to 5V Automatic process, but many of them are manual with a potentiometer. Enough amps for machines with lots of upgrades. Without testing I'm guessing 4A would be ok. (What is the maximum current consumption of a heavily upgraded machine?). Good accuracy to 5.0V. A converter should be better than a linear voltage regulator, according to this video. After researching, not to many options for the job: Pololu 5V Step-Up/Step-Down Voltage Regulator S18V20F5 Maximum output current: 2A 4% accuracy Input voltage: 2.9V to 32V USD 14.95 Pololu 5V Step-Up/Step-Down Voltage Regulator S9V11F5 Maximum continuous output current: 1.5A +5/-3% accuracy Input voltage: 2V to 16V USD 5.95 However with the above devices I'm not fully happy. They have a wide input voltage resulting in few accuracy (ex: 5V * 1.05 = 5.25V). I think the proper one should be something in the range of an input of 4-6V, with an accuracy of less than 2%, and an output over 4A. Has anyone tested any of the Pololu regulators or any other? Quote Link to comment Share on other sites More sharing options...
archeocomp Posted June 26, 2020 Share Posted June 26, 2020 You want to install switching regulator in between output of your linear power supply and Atari? If so it is not good idea. Better fix your linear ps. Quote Link to comment Share on other sites More sharing options...
tane Posted June 26, 2020 Author Share Posted June 26, 2020 2 minutes ago, archeocomp said: You want to install switching regulator in between output of your linear power supply and Atari? If so it is not good idea. Why not? 2 minutes ago, archeocomp said: Better fix your linear ps. The idea is to install a protection and not to be worried about the quality of the power supply, for anyone who wants to plug the device. Quote Link to comment Share on other sites More sharing options...
archeocomp Posted June 26, 2020 Share Posted June 26, 2020 Regulator will worsen already bad efficiency of linear ps, that means it will be even hotter, because it will have to supply even more current. Ripple and noise of switching regulator is worse that that of linear one, that means more noise in video. Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted June 26, 2020 Share Posted June 26, 2020 This isn't nearly as complicated as the OP seems to think. An Atari will rarely need more than 1.5A, even loaded up with an Ultimate 1MB, a UAV, etc. Completely reliable, low-noise switching PSUs in this range are dirt cheap. If you want to rig up your own circuit, these work extremely well (I have one of them inside my 1088XLD, per Mytek's design). https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=TPSM84205 1 Quote Link to comment Share on other sites More sharing options...
archeocomp Posted June 26, 2020 Share Posted June 26, 2020 27 minutes ago, tane said: The idea is to install a protection and not to be worried about the quality of the power supply, for anyone who wants to plug the device. That's clear. Better replace your dodgy linear 7805 (IIRC that is already third one) with that TPSM84205 or a TRACO TSR 2-2450 or a Murata and done. Cool and safe. Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted June 27, 2020 Share Posted June 27, 2020 I think what you want is called a 'crowbar'. (in the old, old days, they would throw an iron crowbar across the bussbar, tripping the circuit breaker, if the power regulator ran away ) It watches the output voltage and blows the fuse if it gets too high. If you use an LM340-5 as your regulator, it really isn't necessary. Bob 2 Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted June 27, 2020 Share Posted June 27, 2020 Bob is great! A good heavy duty crowbar type zener will blow the Ingot before it can damage the computer. :) Quote Link to comment Share on other sites More sharing options...
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