I finished work on the Core module, so it's time to put a few things together to see if they work as planned. Here you can see the Core module and a Bar Graph board wired together along with a speaker and the transformer. All the functions work as intended, although I decided to make a simplification of the parallel port activity detector. I had two one-shots wired in series, but I decided that was over complicated. It works just fine with just one that times out if the CS- signal stays inactive too long.

I also made a small change to adapt to the bi-color LED I had on hand. The original design assumed a three leaded type, with a common cathode. The ones in the parts drawer have two leads. The Red and Green die are back-to-back. Easy change since the '4538 one-shot has Q and Q- outputs.

I've been using LM3915's in the Bar Graph boards. Those are the logarithmic scale variant of the LM391x family. I thought it made more sense for the first modules which will be monitoring radio frequencies. Future modules will monitor things like magnetic field strength, so I may go to the LM3914, which has a linear scale.



Here's a shot of the first front panel for the Bar Graph board. I need to tweak the locations of the three holes for the trim-pots, but otherwise I'm really happy with the results. I did a layout in Visio, printed it out, and stuck it to the blank metal part with spray glue. Very carefully center punched the hole locations, and drilled away. My printer had to be set to 101% to get the most accurate output for this. Always check the printed page carefully before cutting/drilling from it.

I still need to decide how to label each panel. I want to have some text that tells me what's being monitored. I may try the decal sheets I bought from Micro-Mark. They look pretty good over simple brushed aluminum.

Next up, I'll do the rack panel work to hold all this stuff.

Cheers,

Keith