sunset1 Posted July 10, 2021 Share Posted July 10, 2021 Regarding electronic devices, in terms of calculating how many watts a device draws, say a WiFi modem, does one calculate the input or the output on the dc converter? the specs are as follows input 240v 0.8amps (192watts) output 12v 2 amps ( 24 watts) there seems to be quite a big wattage difference Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 11, 2021 Share Posted July 11, 2021 15 hours ago, sunset1 said: input 240v 0.8amps (192watts) output 12v 2 amps ( 24 watts) there seems to be quite a big wattage difference Typically, input specifications are for the peak power ever seen, so you can design the power supply to cater for that need. A power supply often has a turn-on surge that lasts less than a second; that would be where the 192 watts comes from. The power supply's output rating is generally a continuous rating; it should be able to supply 12 V at 2 A all day. So IF the load was at maximum, that's 24 W as you say, so most of the time the input power would be about 10% more than that, say 26 W, with a brief excursion to a maximum of 192 W at switch-on. Tim003 1 Quote Link to comment Share on other sites More sharing options...
sunset1 Posted July 11, 2021 Author Share Posted July 11, 2021 1 hour ago, Coulomb said: Typically, input specifications are for the peak power ever seen, so you can design the power supply to cater for that need. A power supply often has a turn-on surge that lasts less than a second; that would be where the 192 watts comes from. The power supply's output rating is generally a continuous rating; it should be able to supply 12 V at 2 A all day. So IF the load was at maximum, that's 24 W as you say, so most of the time the input power would be about 10% more than that, say 26 W, with a brief excursion to a maximum of 192 W at switch-on. AH ok thanks for the explanation! I thought maybe the adapter was just burning the difference (192 watts - 24 watts) in stepping down the watts and was thinking, that sure is a waste of x amount of watts lol. thanks for the help again. Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 13, 2021 Share Posted July 13, 2021 On 2021/07/12 at 12:01 AM, sunset1 said: I thought maybe the adapter was just burning the difference (192 watts - 24 watts) If it was, it would be getting burning hot! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.