Built my first DIY project yesterday - newbie walk through

It's lunchtime and the client has a very relaxed view on internet access - so I am back....

There is a reason I have done the build this way and the reason is teaching myself - why and where.
As in "Why is that there?" "Where does that lead to?"

I have almost finished Bo Hansens big 48v Phantom Power PSU

This is how I did it...
Got some graph paper and the dimensions of every part and drew myself a circuit with lots of rubbing out and pencil marks and finally rubbed out a few more bits as I had forgot to put some space for PCB mouting holes
Marked out in Bold on the same graph paper - the holes where the components, heat sinks and transforomer went and the correct size of the holes (e.g. 3.5mm, 1.5mm)
Then got a piece of tracing paper and traced the holes from the graph paper onto it
I taped the tracing paper to a PCB board then used a metal drill bench press thingie (cheap £39.99 one from Machine Mart) to drill the holes - I used the drill on the copper side uppermost (If I put it the other way around - I found that the copper started to scratch)
Now I used one of those PCB felt tip pens and redrew the circuit on the PCB - all the lines etc..

Then - I got one of those student bags of Etch Chemicals where the pelletes are in a lower bag and you put warm water into the top bag and then opened up the top to bottom bag so the water hit the Etch pellets and dissolved them
Put the PCB board into it and then it took about 8 minutes of moving the bag aorund for all of the copper to go
Washed out the board and resealed the bag
Got some wire wool and rubbed of the Felt tip pen stuff...
One finished - very amateur PCB with copper trace!
Mounted up the components - the bitch was a transistor into a horizontal TO220 heat sink - what a bitch to try and get the screw in (next time - bigger hole!!)
Soldered everything in...
A bit of splatter of some honey type substance on the board (I presume this to be flux?)
Made one adjustment to Bo's Design - stuck a 2.7k 1W resistor between the +48v and 0 rails just before the end of the circuit - with the aim of providing a blue LED on the front panel to show it's working
One question...
Haven't fired it up yet...cos I haven't done the metal work but does this sound right to test
Put a LED in the circuit (I have put jumpers in for it)
Use a mains chassis socket with a kettle lead and connect the socket to the transformer jumpers for live and neutral
BUT what do I do with mains earth? I haven;t built the chassis yet?
Next - I will measure the 48v and 0v jumpers out - I presume it it says 48v on my multimeter I will be one happy bunny....

Not the easiest way of doign it - but for me I learnt an awful lot about where stuff should go...
rather than just photcopy an existing PCB design (in effect I drew the thing out 3 times)

Hey Simon,
That's almost exactly the way I made my first board...and it worked too..!!
Nothing like making something for the first time and getting it right.

" (I presume this to be flux?) "

Yes. I usually scrape it off with a bluntish instrument.

"stuck a 2.7k 1W resistor between the +48v and 0 rails"

For 48V I'd stick in 10K or so. Take out the jumpers if you have no led yet.

"BUT what do I do with mains earth?"

Take it to 0V on the circuit board.

peter

Simon,

That's how I made my first boards about 20 years ago. I suggest you download Eagle (www.cadsoft.de) , they have a free version. What I do now is draw the schematic in Eagle, design the board using Eagle (no more pencil erasers, I let the software helped me where to route what hole to what hole).

When everything is done, I do an export of the bitmap image (300dpi/600dpi), print that image from a graphics program into a "press-n-peel" blue paper (www.allelectronics.com), and iron the design on the copper board using a hot iron. Etch, clean the PCB, drill, then you're done.

You still do all the work yourself, but everything's on the computer screen. It's much better than the sharpie pen and dry transfer method.

Owel

Simon,

All sounding good so far!

I still use the pen-etch method if I need a quick and easy board- you can draft them relatively quickly and it's straight in the etch tank.

I second the Eagle reccomendation- great program.

Let us know how it goes when you fire it up! If you're using a metal cased transformer rather than a toroid you may want to connect mains earth to the transformer casing as well as 0V. Just wrap the end of a wire around a bolt fixed through the mounting hole of the transformer bracket. No need for this with a toroid- they're very well insulated.

Good luck!

Mark