Can anyone help me out. Does anyone one know what formulas to use to figure out what the conversion is from going to a 12V 850ma DC to 5v DC. Or from a 5V 2.5A to 3.3v. I'm trying to figure out what amperage I'll get when using the lower voltage rail.
Thanks in advance,
Power conversions
-
- Posts: 109
- Joined: Wed Nov 23, 2016 10:19 am
- Has thanked: 3 times
- Been thanked: 74 times
Re: Power conversions
It depends on what method you are using to convert your higher voltage to a lower voltage. If you are using a linear regulator (easiest way) then the current does not change, the current at the lower voltage is the same as at the higher voltage.Villemus wrote: ↑Thu Aug 30, 2018 6:43 pmCan anyone help me out. Does anyone one know what formulas to use to figure out what the conversion is from going to a 12V 850ma DC to 5v DC. Or from a 5V 2.5A to 3.3v. I'm trying to figure out what amperage I'll get when using the lower voltage rail.
Thanks in advance,
If you are using a switching scheme, then power is conserved, with some adjustment for regulator efficiency. So current out at your lower voltage is:
low current = ((high voltage * high current)/low voltage) * efficiency
So for example with your 12V scheme, and 90% efficiency, you would have:
5V current = ((12V * 0.85A)/5V)*0.9 = 1.83A of available current at 5V
Re: Power conversions
Thanks for the thorough explanation. what I'm trying to do, is fix my old NES. I lost the AC adaptor, and I've read a lot of places that you're better off switching to a 12V power supply for a more universal connection since the 7805 voltage regulator can handle up to 18V. I'm still doing research, but I wanted to see if I would have to account for the current since 10Vx1.3A=13W and 12Vx1.3=15.6W. The 5V to 3.3V was out of curiousity for a possible future project.
- Helder
- Trailblazer
- Posts: 2985
- Joined: Thu May 05, 2016 8:33 am
- Location: Rogers, AR
- Has thanked: 1459 times
- Been thanked: 3114 times
Re: Power conversions
Just get a 9v-12v DC adapter and NOT an AC one like the NES originally had. I use one used for my other system on the NES but I replaced the DC socket to be universal.
Chat with me and other members On Discord
Don't contact me about obtaining my board files (as you will not get them). If my Boards or PCB Kits are sold out, they will be restocked as soon as I can get them and there is demand for them. You can join the mailing list on my Website to be notified when they are available.
Helder's Game Tech Website
We will not support any cloned work so don't come to us with technical issues to resolve, go talk to the cloner for help.
Don't contact me about obtaining my board files (as you will not get them). If my Boards or PCB Kits are sold out, they will be restocked as soon as I can get them and there is demand for them. You can join the mailing list on my Website to be notified when they are available.
Helder's Game Tech Website
We will not support any cloned work so don't come to us with technical issues to resolve, go talk to the cloner for help.
Who is online
Users browsing this forum: No registered users and 1 guest