harolto Posted March 25, 2007 Report Share Posted March 25, 2007 Hey,im having trouble with a circut im trying to build.basicaly i have an unstable voltage of 1.5v-3.1v that i need to switch a 12v relayand the relay needs to stay switched when the volts are removed, untill another switch is pressed (momentary switch).i built a circut using a transistor, a low current (3a 12v) relay, a higher current (40a 12v) relay, some resistors, and a diode, and i cant get it to work.i have a VERY basic knowledge of circuts, could some one help me out? a circut diagram would be great and parts that i need, thanks-Jake Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted March 25, 2007 Report Share Posted March 25, 2007 I don't understand. Post a schematic so we can see if your circuit has potential. Quote Link to comment Share on other sites More sharing options...
jtjohnston Posted March 26, 2007 Report Share Posted March 26, 2007 Created a simple car alarm once.http://jtjohnston.net/relay.PNGPut a jumper from pin 1 to the normally open pin (pin 5).Pin 3 has continuous juice. Juice pin 1 once and the relay will lock on until the ground or juice on pin 3 is broken.Sounds like it might help? Quote Link to comment Share on other sites More sharing options...
harolto Posted March 26, 2007 Author Report Share Posted March 26, 2007 that is sorta the circut, there is bits missing im sure, basicaly i need it to latch when 3v is applied, then unlatch by a buttonalso i need it to stay latched if 12v is disconnected, or stay unlatched (memory sorta thing)any help is much appreciated-Jake Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted March 26, 2007 Report Share Posted March 26, 2007 It looks like you want the small relay to power the big relay. Disconnecting the 12V will turn the small relay off, if it's on, and the big relay won't stay on. The pushbutton switch needs to break series, it looks parallel to the load.The hardest part will be saturating the transistor.The source must be able to supply enough base current, which can be higher than many signal sources output. Quote Link to comment Share on other sites More sharing options...
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