Saturday, 8 September 2012

Realising the Power Supply!

After months of inactivity....

I have etched the PCB for the LM317 variable power supply.  I used the design outlined in the previous post.  It seemed to come out well!  Here are some photographs of the process.


The design printed on glossy paper!


The design ready to be transferred onto the PCB - Get the clothes iron out!


The design transferred onto the PCB ready for etching!


The PCB after etching....Not too bad, some tracks were over etched.


Fanfare!!  The populated PCB, quickly switched on to see it working....I couldn't resist.

So where did things go well?  - The design was well transferred and populating the PCB was very simple.  The spacing between components was excellent!  A professional design would be much harder to put together because space is always at a premium.  Nothing smoked when I switched it on...that's always reassuring!

Where did things go wrong?  - I over etched the PCB (left it too long in the etching fluid)....It meant some of the tracks were broken.  I managed to fix this quickly with some thick braided copper wire.  I also used the wrong package size for the transformer.  I didn't check which transformer I had before I printed the PCB design.  It's a common mistake and one I won't make again for a while. I will probably change the transformer to the correct one as I may well make some of the power supplies as kits for people at my local hack space!    


The underside of the populated PCB - notice the extra holes and repairs!

The next thing to do is put the power supply in an enclosure and get some panel meters.  We need to be able to see what the output voltage and current is and we need to ensure that this is safe to use.  We don't want any accidents or mistakes when there are mains voltages and high current available!  

That's all for now people!  Take care and have fun always....