function Get-Password {
    Param (
        [ValidateRange(8, 20)]
        [int] $PasswordLength = 14,

        [ValidateRange(1, 4)]
        [int] $MinimumSpecialCharacters = 3
    )

    # Specify the range of ASCII characters to use, avoiding ambiguous characters such as 0, O, o
    # also limit the allowed special characters to those which are easy to read
    $punc = 33..33 + 35..38 + 42..43 + 45..45
    $numbers = 50..57
    $letters = 65..78 + 80..90 + 97..110 + 112..122

    # Generate the list of required minimum special characters
    $password = Get-Random -Count $MinimumSpecialCharacters -InputObject $punc `
                           |% -Begin { $aa = $null } `
                              -Process { $aa += ([char]$_) } `
                              -End { $aa }

    # Create the remainder of the password from any of the allowed characters
    $password += Get-Random -Count ($PasswordLength - $MinimumSpecialCharacters) -InputObject ($punc + $numbers + $letters) `
                           |% -Begin { $aa = $null } `
                              -Process { $aa += ([char]$_) } `
                              -End { $aa }

    # Return the password but shuffled to ensure that the password doesn't always start with
    # special characters
    return -join ($password.ToCharArray() | Sort-Object { Get-Random })
}

Get-Password -PasswordLength 14 -MinimumSpecialCharacters 3