I have found another colour schemer on the Color Schemer Online v2 site.
It’s straight forward to use, as you simply select a colour which is specified by either its RGB or hex# value and the schemer produces a group of colours that compliment your original color. You can then lighten or darken the scheme as desired.
These colour schemers are not only handy design tools but they also indirectly teach people about colour. As you play with the schemer the different spreads of colour created show how one slight colour change impacts on whole group of colours.