maddy Posted September 13, 2004 Report Share Posted September 13, 2004 Can any one help me for a circuit that can take 12v 4-6A input and give an out put of 6-8v and 800mA. i am very novice to electronic. Actually i need this circuit for my camera which is using a 7.2v 800mA battery. and i want to use a 12v 4A battery to power it up. plz help me out. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted September 13, 2004 Report Share Posted September 13, 2004 Check out the Projects section for 12V 500ma. I have given the answer to your problem. It is a simple voltage regulator that will take your input and deliver the voltage and current. This will take some design work but maybe I can steer you in the right direction. Use the TIP31A available from radioshack as the main current transistor. Use any lower current transistor as the feedback transistor. Place the feedback directly to the base of the feedback transistor. The resistor from the input to the collector of the feedback transistor will have the same value as the emitter resistor. The mid current of the feedback transistor will determine the value of the input resistor and the emitter resistor. This is all you need. You can tag on a zener if you like at the ouput. This will improve regulation. Quote Link to comment Share on other sites More sharing options...
ante Posted September 13, 2004 Report Share Posted September 13, 2004 maddy,Does the camera draw 800mA or is this the capacity of your battery? Quote Link to comment Share on other sites More sharing options...
maddy Posted September 14, 2004 Author Report Share Posted September 14, 2004 Hi Ante,Its the battery comes with the camera shows 7.2V, 800mAbest regrads,maddy Quote Link to comment Share on other sites More sharing options...
trigger Posted September 14, 2004 Report Share Posted September 14, 2004 the marking on the battery is showing mAH, i.e. milli-ampere hour.By dividing it with the current drawn by the unit, you can guess how much hour your unit can use (for the battery is fully charged)So it needed not a supply to give out 800mA for your application.Just a simple regulator circuit will do. Quote Link to comment Share on other sites More sharing options...
ante Posted September 14, 2004 Report Share Posted September 14, 2004 maddy,I would use a LM78S08 on a small heatsink and a pair of caps, that Quote Link to comment Share on other sites More sharing options...
MP Posted September 16, 2004 Report Share Posted September 16, 2004 Ante, I recall it was not so long ago that one could not find a 9 volt regulator. We used to use these with a diode on the center pin to lift it enough to power a 9 volt circuit. Just thought I would add this advise. When tweaking on a standard value regulator for a non standard value, you can always add diodes to the ground pin to move it up or down a bit.MP Quote Link to comment Share on other sites More sharing options...
ante Posted September 16, 2004 Report Share Posted September 16, 2004 MP,Yes, tweaking these regulators has Quote Link to comment Share on other sites More sharing options...
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