Making the Voltage Regulator

Essentially this entire project is very simple!! We are taking a 12 volt CCTV battery and running the ouput thru an electronic regulator which can adjust the voltage from 2 volts right up to 10 volts to suit any camera. Most modern cameras use 7.2volt batteries and their DC power in points expect around 7.4 volts so the regulator board will be able to do just that!!
If you have messed around with building electronic components already then I have included the schematic for those who don't need step-by-step guidance. You can just assemble it your own way but if you don't understand the schematic ignore it and continue reading the step by step assembly details below.
Ok, lets start and make the pre-drilled circuit board the right size for the job..called VEROBOARD ..it's basically strips of copper with holes drilled every 2mm so you can create a circuit board easily. We now need to break off a piece that is 4 strips wide and 8 holes long so use a box cutter to score along the 5th strip and then it will break off cleanly. Now score a line 9 holes along and you should end up with a piece that looks like the image above. You can clean the rough edges with sandpaper if you wish.
To make things very simple we will reference the strips (looking at them from the copper side) as A, B, C and D as shown above. We will also number the pre-drilled holes from 1 to 8. Now we do need to isolate a few strips and in this case we need to split the rows B and C and we do this by using a drill bit in our fingers and just twisting it so the copper strip is drilled away and each part of the B and C strips are isolated.
Right, I have already done this little job using the drill bit in the picture..it takes only a second or two as you only want to remove the copper and NOT drill right thru so USE YOU FINGERS and gently twist the drill in hole B4 first until the copper is clear and then do hole C4 the same. The image above shows you what it should look like.
OK?? Let's do step 1 - Take a short piece of solid wire and insert it between the holes B2 and D2 (remember we are referencing the co-ordinates from the copper side so the link wire will come thru the 2nd holes from the left on the 2nd and 4th copper strips) now solder the wire link in position and we are done.
Step 2 - Push the 2K potentiometer thru the holes A3, B1 and C3 and then also solder the little "legs" where they protrude thru the circuit board. This "pot" will allow you to adjust your voltage output.
Step 3 - Take the 0.1uf Capacitor and insert it thru the holes C5 and D5 and then take the 240 ohm resistor and push it thru holes A5 and B5. Right?? solder all 4 points and then trim off the excess wire with a pair of side cutters.
Step 4 - Take the 1uf capacity but now we have to be slightly careful as this one needs to be inserted the correct way around. On the capacitor one side will be marked "-" and will also have a grey stripe running down the capacitor from top to bottom..this is the negative wire and the other wire is the positive. You need to make sure the positive wire goes into the B6 hole and the negative wire goes into the D6 hole. Double check that you have it the correct way around and then solder the wires to the circuit board and trim off the excess wire.
Step 5 - Take the LM350 chip and use a little bolt to attach it to the heatsink as shown on the left of the image.. the heat sink is purely there to keep things cool!! Now, as shown you can either solder the 3 connectors directly to the underside of the points A8, B8 and C8 or you can pass the leads thru the circuit board and then solder. If you use the second option you will need a tiny drill bit to enlarge the board holes just a fraction as they are drilled out at 0.9mm and the chip's legs are 1mm (that's why soldering on the back is easier) NB: this MUST be soldered the correct way around as shown. If you look at the front of the device the first terminal on the left MUST go the the A8 terminal on the board. It will not work if you reverse it!! so solder exactly as shown. OK that's the circuit board completed so we now need to do one final step.
Step 6 - Take the chip and heatsink and gently bend it 90 degrees as shown to keep it neat. Our final step is to connect some input cables (from the battery) and an output cable (to your camera)!! but we will do that a little later when we assemble the case and battery. Just for reference we will be using the holes C7 and D7 for the cables coming from the 12volt battery and the holes B7 and D8 for the camera cable.
That's about all we need to do at this stage so let's now make the optional LED monitor board (if you don't want it just skip the next page - Click the Step 3 link below Back to the previous Page STEP 3 - Making the LED Battery Monitor Board