You will want to use a switching regulator to avoid heat issues. There are many switching regulators on the market. You can hack together a circuit to make them regulate current.

However, there are specialized switching regulators that are meant for use as constant-current sources. These are often marketed as LED Drivers. If you simply look for these, you will find a wide selection of switching regulators that will satisfy your requirements without modification. This one looks perfect.

6A Current Source
I am new MVC user and I am trying to make shopping cart as following  MVC Music Store tutorial

I am trying to pass the radiobutton value which is different price types through actionlink.
Is it possible to pass the value with productId?
When I click the link, it will call 'AddToCart' method.
Could you help me? thanks.

Product model

namespace MvcApplication2.Models
{
public class Product
{
    [Key] public int productId { get; set; }
    public int categoryId { get; set; }
    [Required(ErrorMessage = "Product model name is required")]
    public String model { get; set; }
    [DisplayFormat(DataFormatString = "{0:0.#}")]
    public decimal displaySize { get; set; }
    public String processor { get; set; }
    public int ramSize { get; set; }
    public int capacity { get; set; }
    public String colour { get; set; }
    public String description { get; set; }
    public decimal price { get; set; }
    public decimal threeDayPrice { get; set; }
    public decimal aWeekPrice { get; set; }
    public decimal twoWeekPrice { get; set; }
    public decimal aMonthPrice { get; set; }
    public decimal threeMonthPrice { get; set; }
    public decimal sixMonthPrice { get; set; }
    //public decimal sixMonthPrice { get { return price * 0.25M; } }
    public int stock { get; set; }
    public virtual Category Category { get; set; }
}
}


details.cshtml

@model MvcApplication2.Models.Product
&lt;td&gt;
        Rental Period: &lt;br /&gt;
        @using (Html.BeginForm())
        { 
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, Model.threeDayPrice) 
            3 day: £@Model.threeDayPrice
            &lt;/div&gt;
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, Model.aWeekPrice)
            1 week: £@Model.aWeekPrice 
            &lt;/div&gt;
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, @Model.twoWeekPrice)
            2 week: £@Model.twoWeekPrice 
            &lt;/div&gt;
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, @Model.twoWeekPrice)
            1 month: £@Model.twoWeekPrice 
            &lt;/div&gt;
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, @Model.threeMonthPrice)
            3 month: £@Model.threeMonthPrice 
            &lt;/div&gt;
            &lt;div class="display-label"&gt;
            @Html.RadioButtonFor(model =&gt; model.price, @Model.sixMonthPrice)
            6 month: £@Model.sixMonthPrice 
            &lt;/div&gt;
        }      
    &lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;p class="button" style="margin-left:200px; width:90px;"&gt;
    //Is it possible to submit the selected radiobutton value through this?
    @Html.ActionLink("Add to cart", "AddToCart", "ShoppingCart", new { id = Model.productId }, "")
&lt;/p&gt;


---Added controller---
ShoppingCartController.cs

 public ActionResult AddToCart(int id)
    {
        // Retrieve the product from the database
        var addedProduct = db.Product
            .Single(product =&gt; product.productId == id);

        // Add it to the shopping cart
        var cart = ShoppingCart.GetCart(this.HttpContext);

        cart.AddToCart(addedProduct);

        // Go back to the main store page for more shopping
        return RedirectToAction("Index");
    }

