How do I prevent a voltage drop when powering 4 devices from one battery?

Question

Hi there again,

I have made a circuit that consists of a 7.4V lipo being stepped down to 5V using a resistor in order for a DC-DC converter to step it up to 12V.

I have used a DC wire splitter used for CCTV cameras. It converts 1 DC output into 4 DC outputs. I am now getting 12V on all four outputs.

However my problem is that I am going to power a CCTV camera, transmitter and audio pre amp for the mic using up 3 of the 4 wires. But as soon as I connect the audio pre amp the voltage drops down to 8V on all four wires. I have already measured the current draw and it is only 20.5mA so I really dont know what is causing the voltage drop and how can I resolve it so that I get 12V on all 4 wires and solve the voltage drop? Thanks.

Answer 1

you need to build yourself a linear regulator!! you lose regulation by dropping voltage across the resistor, as your demand on the supply goes up, you lose regulation.

Copy the linear regulator in the ASTRON 12v 35a power supply (schematics at www.repeater-builder.com). it uses a stable LM723 IC and 2N3055 pass transistors.

Answer 2

You may need a stronger current supply. Try increasing the value of the regulator capacitor. Use 18V + and higher microfarad capacitor and maybe as well as increase the value of the diodes. I have a power supply it reads 13v-15v with car stereo as load, but when I add an amp, it drops to say 10v, so I pulled out those transistors and do the basic full wave ckt and add an 20V and a higher capacitance condenser. Without load it reads 18V, and when everything is connected, it steadily reads at 13.5V.. just do trial and error.