Character Validation in vb.net 2005 without using control

' Text validator
Public Function CharValid(ByVal key_char As String) As Int32
If (Microsoft.VisualBasic.Asc(key_char) <> 90) _
And (Microsoft.VisualBasic.Asc(key_char) <> 122) Then
'Allowed space
If (Microsoft.VisualBasic.Asc(key_char) <> 32) Then
'e.Handled = True
handel1 = True
End If
End If
' Allowed backspace
If (Microsoft.VisualBasic.Asc(key_char) = 8) Then
'e.Handled = False
handel1 = False
End If
If handel1 = True Then
Return 1
Else
Return 0
End If
End Function