Equipment Rack

Equipment Rack

I now have quite a few instruments for electronics, some scopes a logic analyser and a thurlby multimeter/serial analyser/scope. the end of the workbench now has a gap after the shelves were built, and I was going to fill it in with a piece of worktop. Then I measured the instruments and found that they all fit in the gap. So, after a quick bit of wood bashing:



I have used some scrap wood and old flooring and made a simple rack for the equipment:

The rack is on wheels so can be moved about. I am hoping that the space freed up on the workbench will be more than I would have gained by filling the gap where the rack sits with more worktop. I think it will as I can have the logic analyser and scope next to something I'm working on and take up no bench space. We'll see.

As it's made of scrap wood, I could just dismantle it if it doesn't work out.

LA4800 Pod

One circuit of a pod and some routing and we have a pod for the LA4800:

It's a bit big as I just wanted to see if the circuit was correct and I anticipated lots of scoping. As it turned out the only problem was the transistor pinouts and the orientation of the pod cable sockets. Neither of which is much of a problem. as the pod works.

Here's a quick trace of some signals on the Epson HX-20 IO port.

The analyser works perfectly as far as I can see, apart from the display problems, which really are a shame.
I had to solder wires on for this test as the clips I ordered haven't arrived yet, but that's fine.

Logic Analyser

When I needed to look at waveforms on a digital interface recently, I used my Rigol scope as a logic analyser. It's not a mixed signal scope, but it has some features that allow it to be a 4 channel logic analyser. It can decode a parallel 4 bit bus as hex, for instance. It was right at the limit of what it can do, but as a logic analyser it was really at the bottom end of what I wanted it to do. So I looked about for logic analysers. There's a lot of the HP analysers about but they tend to need software on floppy disks and they will be decaying and get harder to find as time goes by, and they are mechanical and that is always the first thing to go.

Then I saw the Thurby Thandar (or TTi as they are now) LA4800 logic analyser.

It has it's firmware in ROM, and has 48 channels. It can go to 100MHz, but runs slower with normal pods. As an added bonus the service manual is on the internet, which makes it fixable.

I saw one on ebay and bought it, unfortunately without any pods. This isn't a massive problem as the service manual has the pod schematics, so I'm having a go at making a pod for it. Just a simple 32 channel pod, we'll see how it goes.

The analyser suffered a bit in transit and the display has a couple of odd faults on it, which is a real shame, maybe I'll find another one as a spares machine? Anyway it didn't start up when it arrived either, but it looks like it had a drop on the way here and the display connector had moved a bit, as after unplugging and replacing the display connector it works.

I'm currently routing a pod PCB...