Lets have some fun with an LM317 voltage regulator.
I made up some of these using strip board for the lighting on my trams. They seemed to work well untill the vero board fell apart.... Sooooooo I bit the chip ( as it were) and made up some PCBs that I can use to a) act as constant light supplies on the trams ( but of course they would work driving leds any where) and b) to provide power to my 3v LED street lights....
let me point out that electronics is NOT MY FORTE, immodest as it may sound my soldering skills are up there with the best, I was trained at HMS Albatross for HRHS but design and theory are sadly lacking....
But this is a very simple circuit. Anyway I made it all up and connected it up and kept getting the supply voltage as the output. Ahhhh then the big led turned on and I realised that there was no load, as soon as I put a load across the output all was well. The trimpot lets me twiddle and get exactly the voltage I want. My current boards are made up to use fixed resistors allowing them to be smaller.
The heat sink is also an add on, the chip became a crisp when I tried to draw an amp thru it so I put the heat sink on to act as a radiator. This board also has a rectifier on it but to make it a directional lighting board a diode and wire link will do that. The current limiting resistor is 1 watt to handle the load, it's a token 12 ohms, I'm not sure that it's needed but it makes me feel all warm and squidgy having it there, following the golden rule of electronic design No 1 " It has to look complicated". I should be able to run around 50 leds from 12 V with this. That saves me a lot of soldering or resistors onto leds, the pre wired,12v ones are hard to fit into small places. Will each LED be the same brightness? Well probably not as each has its own internal tolerances but using decent wire on the supply the drop should be minimal. I use speaker figure 8 (oxygen free of course) as it is very flexible and has a decent core, ideal for low loss... It's also cheaper than normal figure 8 for some reason.... Notice how the tracks on the PCB conform with best tramway ( but not electronics) practise??? If anyone wants any let me know, I could also email HiRes artwork....
I made up some of these using strip board for the lighting on my trams. They seemed to work well untill the vero board fell apart.... Sooooooo I bit the chip ( as it were) and made up some PCBs that I can use to a) act as constant light supplies on the trams ( but of course they would work driving leds any where) and b) to provide power to my 3v LED street lights....
let me point out that electronics is NOT MY FORTE, immodest as it may sound my soldering skills are up there with the best, I was trained at HMS Albatross for HRHS but design and theory are sadly lacking....
But this is a very simple circuit. Anyway I made it all up and connected it up and kept getting the supply voltage as the output. Ahhhh then the big led turned on and I realised that there was no load, as soon as I put a load across the output all was well. The trimpot lets me twiddle and get exactly the voltage I want. My current boards are made up to use fixed resistors allowing them to be smaller.
The heat sink is also an add on, the chip became a crisp when I tried to draw an amp thru it so I put the heat sink on to act as a radiator. This board also has a rectifier on it but to make it a directional lighting board a diode and wire link will do that. The current limiting resistor is 1 watt to handle the load, it's a token 12 ohms, I'm not sure that it's needed but it makes me feel all warm and squidgy having it there, following the golden rule of electronic design No 1 " It has to look complicated". I should be able to run around 50 leds from 12 V with this. That saves me a lot of soldering or resistors onto leds, the pre wired,12v ones are hard to fit into small places. Will each LED be the same brightness? Well probably not as each has its own internal tolerances but using decent wire on the supply the drop should be minimal. I use speaker figure 8 (oxygen free of course) as it is very flexible and has a decent core, ideal for low loss... It's also cheaper than normal figure 8 for some reason.... Notice how the tracks on the PCB conform with best tramway ( but not electronics) practise??? If anyone wants any let me know, I could also email HiRes artwork....
Why the pics are in B&W I have no idea, maybe a precursor to the end of the world as we know it??
