I have two devices I need to power. One is a CCD card and the other is a "bunch" of LED lights. The CCD card works with 12VDC and the LED lights work with 18 to 30 VDC. Originaly these devices were supplied with a 24V power source. Not sure if it was AC or DC ( I am guessing DC by the diagnostic chart I had for this setup)

The existing cable I have has 4 wires wrapped in foil and a drain/ground/shiled wire on the outside of those 4.

Two of the 4 wires are needed for the video feed from the CCD.

Can I somehow take 2 car batteries in series and split the voltage into two seperate sources using only the 3 remaining wires? I thought I could do this with a voltage divider and soon learned that this basic circuit just reduces the supply votage.

Reason I want to use car batteries is becasue they tend to last for a very long time when drawing very small amps. AND to top it off I am running 300 feet of cable between the power source and my devices.

TIA for any help.

Craig

 

Why not use a doorbell transformer to power them?

Yes, the output from a doorbell transformer is 24vac. However, when rectified, the output will approach 33v.

You don't mention the devices' current requirements.

 

you could use an on-board DC-DC converter. You could put 2 car batteries in series, to get 24V, then run the 24V to a buck converter to drive the CCD (I am assuming it is pretty low power). YOu can buy some off the shelf, or build one.

 

Thanks for the quick replies.

Further info:

The current requirements for the devices are unknown.

What I do know is:

The LED lights will light up using 3 9V batteries in series over 300 feet of wiring.

The CCD card will work anywhere from 11.5+/- Volts to 13volts+/-. Anything less or more than that the CCD card will not work.

My goal is to be able to light up the LED lights using the 24 volts from car batteries in series and then also be able to run 12V to the CCD card.

I had a power source originaly for this setup up, but the all the equipment I am using was stored in a trailer and was broken into. The power source was stolen so I have no idea what it was. Where the CCD card is there is a circuit board with a few transistors, caps, diodes, and a chip. I am guessing that this card acts what was described above (buck converter) but not sure. I could always post pictures of the board and trace out the circuit and post that if that would help.

Thanks again for the help.

 

Yes you can use to car batteries in series to produce 24V and 12V. You will get the 24V across both batteries and the 12V across one battery only. Note that the battery which will be used as the 12V too will discharge quicker.

 

Yes you can use to car batteries in series to produce 24V and 12V. You will get the 24V across both batteries and the 12V across one battery only. Note that the battery which will be used as the 12V too will discharge quicker. Also, take care because car batteries are charged to more than 13V and this may damage your device.

 

Thanks for the replies, hop-e everyone had a great Christmas!

I traced out the circuit on the board and was hoping that someone could tell me what exactly it is doing and what the supply voltage is. To me I think it is a way to amplify the video signal (over 300 ft) and reduce voltage coming in, but don't know for sure. Everything I know I pick up along the way with various projects here and there so any explantation would be great..

Also, would the input voltage be 24V DC or 24 AC? The diagnostic that I have for the power source tells me to set my meter to 20VDC and use the negative probe on the green wire of the 5 pin connector and measure between the orange wire to see if there is +24V and then measure between the green and the red wire to see if there is -24V....

 

Sorry, didn't realize the pic was unreadable...

 

From the diagram posted, you should use the following:

Voltage In 1 requires -9 Volts (A positive voltages in this input will destroy the negative regulator and seriusly demage the capacitors)

Voltage In 3 requires +18 Volts

Out 3 state -12 V but is ground so you will have 12 volts from out 3 and out 4 (coming from 7812)

Outled 1 = ground
Outled 2 = +18 Volts


Alberto