Hi I can help you do this simply but I need some details If you would like I can call you, I will send you an offer, so we can work on this until its fixed, If you don't want that just disregard the offer.
and we can do this here in text.
Hi clear this up for me. I see you want to suply with 110 vac, what is the voltage you need to achieve? Also would you be ok with something that supplies more then 250 MA, you said up top 250 ohm? Wast that a typo as I suspect?
Hi I`m Jack ,different tech. here
I believe you got your ohms law backwards here .
Your source is 120 volts and that's not variable so while it is correct that a 250 ohms load under 200 volts will give you approx. 800 milliamp (.8) , your source is not variable unless you where to use step up transformers.
Now if you use a constant voltage source like 120 volts and then a step down transfo 240/120 when oversea then you have a constant voltage source .
Now usually device will draw a specific amount of currents depending on the devices and the object of a power source is to be able to supply (in voltage and current) the device that loads that power supply .
For example if your device draws .8 amp then you want a power supply capable of delivering above that under a constant voltage not a constant current , that does not exist , the load determines the current draw not the power supply .
For example what you would need is a power supply that can deliver 1 amp and above if your device needs .8 amp
May be easier if you just said what it is that you want to power up and what voltage it works under , is it AC voltage or DC that you need ?
You never said what this was to be used for , I`m a practical guy and I like to know what I`m working with and right now thank you for the electronic course but we`ll call it a day shall we .
I will repost your question.