Saturday, 26 May 2012

PCBs and Happy Times !!

So here is a sneak peek to the new PCBs.  They look good even though it is only the standard green, but once they are in an enclosure, well, you don't see them much anymore.

The switch and LED board is up top and you can see the main PCB here.  I started populating the boards a couple of days ago.  I only hooked up the power supply section, the microcontroller section and the low pass filters.  Thus leaving the power op-amps out so I could verify stage by stage.  The power supply was built up but I left out a series resistor that feeds the power to the board so that I could check it out before powering up the rest of the circuit.  The power supply looked to be working very well, with very low ripple.  Happy there.  Then I checked out the microcontroller section by powering it from it's USB connector first.  No problems here either, the LCD and buttons worked great.

New PCB layout with fatter traces and ground fill.
So I checked the sine wave outputs on the low pass filter section and happiness here too, the waves looked really nice and clean.  I replaced the single turn output amplitude adjustment pots with nice multi-turn trim pots.  This made the adjustment of precise amplitude easy and worked great.  So far so good.

Next step was to power the microcontroller with the PCB mounted supply.  I placed a pop-out wire jumper for the series resistor (this resistor is only needed in case you are going to install the zener diode voltage clamp which was not needed with the transformer I am using), I used a wire I can remove so that I can measure current draw later on. Measuring all voltages I confirmed that the board was working fine off the on-board power supply.

At this point I am very happy with the unit and next step will be plugging in the op-amps and testing the amplification and output transformer stages.  Coming soon, so check back to see the results.