Controlling relays with 24V coils

Ive got a lot of relays in the parts bin with 24V coils. This is a common control voltage in industrial and telecommunications equipment, so the relays are common in surplus equipment. Many will actuate equally well on AC or DC, which makes them an easy solution when the control voltage is switched mechancially, as in the case of limit switches or magnetic reed switch sensors. Unfortunately, theyre not so simple to interface directly to microcontrollers as they require a separate supply and level shifting circuitry.”