Welcome to this simple mains supply with a battery back up in case the mains cuts out the devise will switch to battery power to power your electronic projects.






1). In the 3 schematics I have designed below this will allow you to build 3 very simple power supplies for your electronic projects.

2). The first is Unregulated this is fine if you don't need a fixed voltage it can be used with most electronic devises.

3). The Second schematic I have designed to be a fixed regulator very useful with 5 volt regulated digital electronic circuits.

4). The third schematic I have designed this devise with a Unregulated & a Regulated out put

5). The devises are designed to switch over to battery power as soon as the mains power supply has been cut out and as soon as the mains power comes back on it will switch to the mains again.

6). All the parts should not be a problem to get hold of they are all off the self components the transformer used is a 500 milliamp version get this from your own country down to the in put voltages.

7). The relay is a DPDT Mains Power Relay Contacts rated 8A/230Vac, 8A/30Vdc. 12Vdc coil 360R order the relay from here.

8). The two Capacitors used in the Regulator are 100uf 25 volts electrolytic order them from Ebay or from your own country Caps with low ESR are the best but any will do.

Please note the relay contacts are showing being powered from the battery, When the mains is on it will switched on to the mains and power your devise that way.


Now in the schematic below you can see I have designed a 5 volt regulator on to my Unregulated power supply.

Now in the Schematic below I have designed a simple power supply with Regulated & Unregulated out puts.


Now if you have any problems please do e-mail me and I will be more than happy to help: e-mail me here: Anthony@anthony-dacko.net

My electronics page here.