amp control question

[grizzley]

i have a bank of 12 V batteries, charged by solar cells, that i want to run a wireless camera with.the cam requires 12 volt 80 mA source.i also have a receiver that requires 500 mA at 12 volts,that will be seperate from the camera. what is the best way to control the amp problem so they don't fry.appreiciate some advice-this is not my speciality.thanks

 

[dpc]

As long as you provide 12V to each device, each one will draw only the current it requires and everything will be fine. Not sure how you plan to wire this, but each device needs to connect to the + and - of the twelve battery - they are in parallel.

 

[Igloo]

You use 80 mA for your camara and the reseiver 500mA.
This is a total of 580 mA that is possible to take from one battery.
The supply wires of the differend units needs to go directly to the battery, in this there is no influence of the differend currents.
This is only if the impedance of the battery is low.
If the impedance of the battery is high the voltage drop will be greater and the charging from solar cells will be higher, this not danger for your Scells because the impedance of the cells.
It could happen if the battery will get a short but if the battery is low there the impedance gets higher and limits the current.

 

[buzzp]

I would put in some extra fuses as well. They likely have there own internal fusing but worth checking out. Buzzp

 

[Lewish]

You need a simple linear low drop-out regulator. Since you are also charging the batteries from solar cells, your voltage will be up around 14.4 volts or so, assuming you are using some type of charge regulator. While the camera and receiver may operate for a while at this higher voltage, it will definitely shorten their life expectancy. You can find these regulators in places like Digi-key or Mouser for a dollar or so. Get a datasheet for the device you select and follow the application notes. Don't you a switching regulator, or you may find your receiver swamped with switcher noise. Hope this helps.

Lewis