i made a couple of these DDL style drivers. they are the same components as the one in the original how to with the 100 ohm pot., just surface mount parts. just curious to see how many people might be interested. [smiley=beer.gif]
give me till this afternoon to check what cost i have in parts it wont be but a couple of dollars. little things are just fun to build. work really well also. they have the same mA range as the large ones with less than an 8mm square size. can fit into almost anything!
the input voltage is the same as the larger DDL type driver (3V+LD voltage). how does $10.00 / ea. sound. i'll go ahead and order more components to keep in stock just in case someone wants some! [smiley=beer.gif] ill post some better pictures soon. i was just in a rush when this one was built and didn't take much time on it.
this is just a proof of concept to see if it can be make and it can. as i said earlier the one in the picture was just kinda "thrown" together. when the parts arrive i will post a better picture of the driver and we can see how it goes from there. about the inductor... long night playing with this project and overlooked it for a resistor. just testing parts in my part bin for a 3ohm to a 5ohm resistor and made a mistake. after it is built i will also post a video with full range on a meter to show that it does work. right now i am waiting on some more parts. should arrive in about 5 business days. [smiley=cheesy.gif]
Just to warn you... if you plan to operate these linear type drivers at what I expect to be currents for 803T diodes or especially red diodes, it looks like there is basically no heatsinking on the IC and may quite possibly overheat after not very long.
You will also have to be very careful to avoid shorting against a metal case or even some of the parts against each other.
Just what I was about to say. In the rckstr drive and such, the PCB acts as a heat sink, but now you are just heating up the parts sitting on the bottom, until they are also hot and nothing cools it anymore.
You might as well go with a LM317L (the TO-92 type) and a max 200mA range. Those can be made small and a little safer (duty cycle still required). I fitted two of those drives in an aixiz at at the same time, with a PCB (not tunable though, but that might be possibly if it's an etched PCB): http://www.laserpointerforums.com/forums/YaBB.pl?num=1215859801
it works great at around 130-150mA for a BR. doesn't get that hot. im not planing on making a business out of this, it was just something that i made for a project of mine and thought it was neat to fit a driver in such a small package. thanks for your input on the topic. oh and there is no components on the bottom of the lm317.