My car Radio/GPS sytem recieves its power from the fuse panel which is switched by the ignition key. I would like to have the ability to turn the radio on without using the ignition. I cannot wire the radio directly to an always on connection becuase it runs a fan on the unit when power is on the line regardless if the radio is playing and it would eventually drain the battery.
I would like to run an always on power supply (through a toggle switch) to the power lead of the radio, but at the same time allow the radio to be powered through the normal ignition switched power supply so if could be powered by the switch (when closed) or by the ignition being on. If I do it though the toggle switch alone, I am afraid my wife will forget to turn the toggle switch off and drain the battery.
My concern is if I run power from the toggle switch at the same time the ignition switch is on will I get a back flow of power to the fuse box, or too much power & amperage to the radio?
If I use a diode, do I need one on each line one to protect the ignition switch and one to protect the toggle switch?
If the always on is 20amps and the radio needs 10amps will the radio only use what it needs or will the 20amp circuit burn out the radio?
+12V 10A Ignition Switched o_________________o__________o Radio
|
+12V 20A Always on o________/ _______|
or do I need to add diodes (not sure if I have the diode in the right direction)
+12V 10A Ignition Switched o_____________|<__o__________o Radio
|
+12V 20A Always on o________/ ___|<__|
If the radio only needs 10amps and the supply gives 20amps do I need to add anything to the circut to reduce the amperage?
Thanks,
Les
I would like to run an always on power supply (through a toggle switch) to the power lead of the radio, but at the same time allow the radio to be powered through the normal ignition switched power supply so if could be powered by the switch (when closed) or by the ignition being on. If I do it though the toggle switch alone, I am afraid my wife will forget to turn the toggle switch off and drain the battery.
My concern is if I run power from the toggle switch at the same time the ignition switch is on will I get a back flow of power to the fuse box, or too much power & amperage to the radio?
If I use a diode, do I need one on each line one to protect the ignition switch and one to protect the toggle switch?
If the always on is 20amps and the radio needs 10amps will the radio only use what it needs or will the 20amp circuit burn out the radio?
+12V 10A Ignition Switched o_________________o__________o Radio
|
+12V 20A Always on o________/ _______|
or do I need to add diodes (not sure if I have the diode in the right direction)
+12V 10A Ignition Switched o_____________|<__o__________o Radio
|
+12V 20A Always on o________/ ___|<__|
If the radio only needs 10amps and the supply gives 20amps do I need to add anything to the circut to reduce the amperage?
Thanks,
Les