Find yourself just about any data book that has information on the
LM317 adjustable voltage regulator.  In there you should find a diagram
and equations for a constant current regulator circuit.
(attempted ascii art below)

  You can do this with two parts, the LM317 and a single
resistor.  Should total less than $2.00

I think the equation for finding the resistor value is  1.2V/A = R
where A is your desired charging current (220mA = 0.22A, so R = 5.45ohms)

                   in  -------------  out    R
raw dc in + ----------|             | -----\/\/\/----> (+) to batt
filtered              |  LM317      |              |
                      |-------------|              |
                         adj |                     |
                             ----------------------|

        (-) ------------------------------------------> (-) to batt
Dave