LCD Vacuum Sensor

[Nicolas Krause]

Thanks John! Was missing the key word octal, was able to find what I needed on eBay!

[Nicolas Krause]

As we're in Christmas holidays I've gotten back to working on the vacuum sensor. I'm currently in the process of laying out the PCB in KiCad. There's lots of finicky details to work through to make sure positioning is correct but the broad outlay of the board is visible. The amplification circuit and connector to the LCD in center, the two 20 pin connectors to hook in the microcontroller board,and on the left a 4 pin terminal connection to connect the wires to thermocouple gauge.

[Nicolas Krause]

Routing on the board is now completed, I still have to pour the ground plane and place some mounts if I want to put it in a case but progress is progress. I'm never 100% sure about how to route things well, but this is a simple circuit so I don't anticipate too many problems.

[Nicolas Krause]

The routing is now complete and all that's left to do is send it off to the board house!

[Richard Hull]

Great work and workaround on getting the sensor data into a computer or data collection and reporting scheme. Sometime we latch onto free stuff or stuff so cheap that to get it to do what we want it to do takes a lot of time and effort to fit it into our needs instead of a lot of money spent buying something ready to go. In doing this, we pick up a lot of learning in the doing. Just another skill under the belt....Ata boy!

Richard Hull

[Nicolas Krause]

I'm just waiting on a relay terminal to complete this board, but I have finished most of the soldering and just have to do some final tests with the program to make sure it runs reliably.

[Cai Arcos]

Is that the Art of Electronics peeking in the corner of the photograph?
Great project too, a really convenient way to measure vacuum!
By the way, have you considered optical isolation or, more simply, just using a usb isolator if you ever connect this to a PC? I feel it would be an easy way to protect your computer and limit the damage of a possible accident.

[Nicolas Krause]

Good eye! Yes it is an art of electronics book (actually 2, 3rd and 2nd edition as the 2nd edition has some neat physics circuits at the back). The plan right now is not to plug the device into my computer but rather to use a USB power supply to run it. The whole board is built around a TI Tiva C Launchpad, which is a development board. At some point in the future I plan to add a logging capability so that I can plug it in to my computer and download the time series pressure measurements but for now its going to sit beside the fusor and give me live pressure measurements.

[Cai Arcos]

Thanks for letting me know about the physics circuits on the 2nd edition, I have only read the 3rd and I am quite surprised by the amount of content that was removed...

[Nicolas Krause]

Just reviewing the board as I run through setting everything up, and I've noticed that I've forgotten a potentiometer on the power supply to the thermocouple gauge. I'll have to complete another revision of the board at some point, but for the immediate I'll probably just cut the power trace on the board and bodge in a potentiometer with some solder and wire.