Brain is mush - electric circuit help needed

map · Mr Calendar Joined: 14 Jun 2004 Karma :

Can't get my brain in gear today.
Going round in circles figuring out a circuit diagram.

Need a circuit to switch on when ignition circuit is off (as bike alarm).
Circuit will draw direct from battery when bike off, disconnected when bike on.
I know a relay will be in there somewhere but more used to using them to switch on with ignition.

Can anyone offer any help?
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger? Very Happy

Git · Brolly Dolly Joined: 17 Dec 2003 Karma :

It can be done easily as long as you have a 5 terminal relay.

Terminals 85 and 86 are used to energize the coil.

Terminals 87 and 30 is the switch, these two only become a circuit when power is applied to the coil and the contact is made.

Terminal 87a is made when the relay is off and broke when the relay is on, if you put the live feed from battery on 30, 87a will be live when switched off.

hope that helped a bit.

Fortuna · World Chat Champion Joined: 29 Oct 2004 Karma :

Edit: Too late, what he said. ^^

map · Mr Calendar Joined: 14 Jun 2004 Karma :

Villers · World Chat Champion Joined: 13 Sep 2004 Karma :

Its just a case of using the 'Normally open' contacts and the 'normally closed' contacts of the relay!