Uninterruptable Power supply (UPS) for cordless telephones

Although the electricity supply will rarely fail in most of the UK, unexpected power cuts lasting several hours are not uncommon in many other countries where this magazine is published. Most inexpensive short-range cordless telephones of the ‘base and handset’ type can no longer be used to make calls when the mains supply fails. This article describes a simple, low-cost battery backup unit which enables you to keep telephoning during a power cut.