EMFs

19 07 2010

All Photos.

David F. volunteered to help out Sunday:

We took another crack at running the DAQ in the face of wicked EMFs coming from the fusor.

David picked up a shielded USB cable for the DAQ:

With the DAQ close to the fusor, but not connected we were able to instantly crash it:

Next we put the unconnected DAQ in a makeshift faraday cage made from a small cabinet:

The cage and the lid are grounded:

Surprisingly, we were able to crash the DAQ pretty easily in this configuration! It’s possible that the panels that make up the cabinet are not connected electrically (seems unlikely). Next step is to upgrade the faraday cage to a made for electronics chassis, preferably rack mounted.

The only way we found to keep the DAQ from crashing is to keep it about 2 meters away from the fusor.

David also diamond filed the ceramic tube to fit inside the HV feedthrough ceramic:





TVS Progress

30 05 2010

All photos.

Wiring up transient voltage suppression for all channels. I’m using shielded twisted pair for interconnects.





TVS Test

29 05 2010

All photos from today.

Worked on the transient voltage suppression system all day.

I wired up a single differential channel on the USB 6008 with TVS protection:

The channel seemed to behave normally with the TVS circuit installed. Next is to test it with a voltage spike. Maybe start with this guy:

Simple Labview VI to monitor the voltage:

Also cleaned up the computer cart:





Transient Voltage Suppression

22 05 2010

All photos

I enjoy drawing my schematics on the whiteboard and snapping a quick picture. This is the schematic for transient voltage suppression going into the USB 6008:

Started wiring it up:

The diodes are heavy duty:

The diode’s leads are too thick for the USB 6008 Prototyping board:

I can still solder these diodes on, but it will get crowded on this board:

So I will also use standard prototyping board:





Lab Time

16 05 2010

Spent some time in the lab. Really loving my new photo blogging capabilities. Shoot first, answer questions later.

Friday’s photo stream.

Saturday’s photo stream.

Received a bunch of parts from mouser. Including the protection diodes.

Prototyping board for NI USB 6008. I should have ordered two!

Did a tour of my shop neighbor’s guitar workshop:

Made progress on the coil power supply chassis:

And played around with ferrofluid:





Transient Voltage Suppression

4 05 2010

When the fusor’s plasma becomes unstable and sparks, it makes my DAQ crash. This is likely due to transient voltage spikes in the wires, or electromagnetic interference through the air.

I’ve been exchanging emails with Raymond R. about the details of voltage suppression. He suggest using TVS diodes to protect each channel of the DAQ from voltage spikes in the wire by clamping them just above  the channel’s operating range.

I’ve ordered these TVS diodes:

1.5KE7.5CA

1.5KE12CA

Raymond suggests the following:

1) Buy the  NI USB-6000 Series Prototyping Accessory if you have the money and want to avoid messiness; otherwise you can kludge the wiring. (I’ve done this).

2) 16 (+ 4,5 spares) of  LCE10A-ND (I bought corresponding parts at mouser).

3) Go to differential mode on NI USB 6008 (good idea).

4) Connect the TVSs from each input/output line to  frame ground.

5) Take the cable shield and do not connect it at the USB board; connect back to the computer frame.  The TVS diodes go to the cable shield not to the USB box grounds.  Connect the USB grounds together and to the shield ground through a 1 meg resistor (alternately a .1 uf ceramic cap).





Call for Schematics

17 04 2010

To the highly involved readers:

Anything you can design and spec (I’m talking schematic and mouser part numbers)…

I can purchase and build.

So if you ever think: “man, famulus should build  X right now”

Send me schematics and part numbers. Provided it’s pertinent to the research and within the budget… I will build it.

——————————————————

Here is a my first schematic challenge:

I just purchased this trigatron for discharging the mega-capacitor:

Here is the schematic for it’s use.

Here is the challenge:

Design a modern version of the triggering circuit shown in this schematic. ie, without using a “break-modulator valve”.





Small Steps

22 09 2009

Today I added a tap point for analog reading from the ion gauge. Pins 3 and 7 according to the manual.

IMG_4076

Assembled:

IMG_4080

Eventually I’d like to use the digital interface, but for now this gets the job done.

Next I added a proper connector to the bench-top power supply (pulled from an old PC):

IMG_4084

This works a lot better than the wire jumper which kept falling out.

We received and tested the 100A/100mV ammeter shunt resister:

IMG_4085We will use this shunt to take current reading going into the superconducting magnet.

Next up we tested out the IGBT:

IMG_4086

Using this schematic:

IMG_4089

It successfully switched 10 mA. Next to try it with more amps.





Reactor Controller / Data Acquisition

17 09 2009

Since the pump broke I’ve been working on the reactor controller / data acquisition system. This will allow us to record:

Voltage reading (via voltage dividers and ammeter shunts); low power voltage reading from magnetometer, thermocouple, pressure gauge, etc; on the output side: voltage control of power supplies, servos for needle valves, triggering IGBTs; Our ion gauge has the option of digital over RS485.

I purchased an NI USB-6008 (manual, driver):

IMG_4042

Unfortunately the driver for this does not work with Snow Leopard yet. I’ve already upgraded my main laptop to Snow Leopard and I really don’t want to downgrade to Leopard so I dug up and old G4 running Tiger. Had to swap out a broken CD drive:

IMG_4038

This G4 will be a challenge to upgrade to Leopard as it lacks a DVD drive, although it may be possible to install without DVD.

I was able to install the driver NI-DAQmx_Base. I opened up NIdatalogger and performed a successful grab of voltage data on the analog input:

NIdatalogger

I would like to get this ruby adapter working. So far I can’t get it to build on Tiger (it makes it further on Snow Leopard). I’m working with the creator to get it installed and working:

make -f Makefile.swig install
swig -ruby -Fstandard -I/Applications/National\ Instruments/NI-DAQmx\ Base/includes -o daqmxbase_wrap.c daqmxbase.i
make: swig: Command not found
make: *** [daqmxbase_wrap.c] Error 127
make -f Makefile.swig install
swig -ruby -Fstandard -I/Applications/National\ Instruments/NI-DAQmx\ Base/includes -o daqmxbase_wrap.c daqmxbase.i
make: swig: Command not found
make: *** [daqmxbase_wrap.c] Error 127
—————-
UPDATE:
I just needed to install SWIG. Although this took roughly 6 hours! It installed without a problem.
I AM UP AND RUNNING with data acquisition in my native programming language ruby.




Grounding

29 08 2009

Spent the last two days throughly grounding the entire system.

We start by attaching a ground line directly to the overhead sprinkler system. First we scrape off the paint:

IMG_3987Then we attach this purpose made ground clip:

IMG_3986

Here it is installed:

IMG_3988

We are using 12 AWG insulated stranded copper. In addition to this pipe ground, we are also using outlet ground from two different circuits:

IMG_3992

Ground each piece of rack equipment, and the rack itself:

IMG_3989

Ground several points on the chamber, sled, and pump:

IMG_3990

Here is the high voltage connection point with high voltage divider inside glass insulation:

IMG_4000








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