Hello Terry, I cant really claim any design for this, I basically stole the circuit diagram out of the datasheet, and I found the component by browsing through an old Jaycar catalogue. The datasheet is available at: http://www.national.com/pf/LM/LM317.html The circuit I have made up is basically identical to the one on the front page, except I lost the two capacitors, they are basically just there to ensure that the output voltage is as clean as possible, not really needed when you have a nice DC input already, and the load is fairly constant. The regulator is like most others in that it has a Vin pin, Vout, and a reference pin. The regulators entire job is to ensure that at any stage there is 1.2v between the reference and the Vout, so if reference were tied to ground, it would just be a 1.2v regulator. In this case, voltage on the reference pin is determined by the 2 resitors, which are connected to form a voltage divider, which basically just means that if you connect 2 resistors in series, and then connect them over a power source, in the middle you have a lesser voltage (depending on the values). The fact that the voltage divider will always show a percentage of the output voltage to the reference pin gives you the adjustability. Sorry if this is wordy, you might want to try to find a better explanation of voltage dividers on the net somewhere.
Monday, February 18, 2002, 8:57:05 PM, you wrote: TR> Thanks Bob, TR> I would certainly like to see how you design this sort of thing. TR> Some explanatory notes on what the bits do would be good. TR> regards TR> Terry TR> -----Original Message----- TR> From: [EMAIL PROTECTED] TR> [mailto:[EMAIL PROTECTED]]On Behalf Of Bob TR> Sent: Monday, 18 February 2002 6:24 PM TR> To: [EMAIL PROTECTED] TR> Subject: Re[8]: 200B fuel tank in 1600 fuel gauge calibration? TR> Hello Chris, TR> I have a regulator working now, total cost was about $3, its TR> adjustable down to about 1.2v. I havent tested its current TR> capabilities yet, but the data sheets on the regulator specify that it TR> can supply 1.5A, so for a fuel gauge it should be heaps. If you were TR> going to use it for anything much higher, I would start thinking about TR> fitting a small heatsink to the regulator itself. Anyone interested in TR> the diagrams I can send them to you, just send me your address. Chris, TR> where abouts do you live? I am in Wollongong, so if you are in the TR> area I can just send it to you or something, otherwise you could make TR> your own for cheap or I can post it to you. TR> Monday, February 18, 2002, 10:50:15 AM, you wrote: -- Best regards, Bob mailto:[EMAIL PROTECTED] --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[email protected]/ ---------------------------------------------------------------------
