Step-up Transformer

28 02 2010

Parts for the coil power supply. Just received a 600v step-up transformer from ebay:

My shop-mate Stuart has a Variac laying around:

Coils Formed

25 02 2010

I received the 18 AWG (1mm diameter) magnet wire today. Now we have actual coils. 10 turns each coil:

Project of the Day

17 02 2010

We are the project of the day on Kickstarter:

Around the Shop

16 02 2010

Today Stuart received a donated two arm SCARA robot and controller:

SRX-340: High speed assembly robot.

The controller is: DRX double arm robot controller.

The equipment is in great shape. The controller turns on, but it seems to be hitting an error with some missing external dependency. Interesting how difficult it is to unlock the value represented by this machine.

We can’t find any documentation on google. If you know details, let us know.

Coil Former Complete

16 02 2010


I plan to replace the screws with stainless steel screws and clean it all in muriatic acid before putting it in a vacuum.

Coil Former Progress

15 02 2010

Did some more work on the coil formers. Stuart and I used the computer controlled milling machine to precisely drill the holes. First we mount the teflon coil former in a chuck:

Then we center the spindle:

Drill the holes:

Next we take some aluminum angle bracket:

Cut them down to size:

Drill the holes:

And tap:


Emergency Stop

14 02 2010

I put together an emergency stop button for the reactor:

This will be positioned a safe distance from the reactor, so you can kill the high voltage from a distance. I’ll wire it up and test it today.

Coil Power Supply

13 02 2010

Joe Khachan just sent me details on the power supply for the coils. They are designed to produce a brief high current pulse.

Joe says:

The part that took the most time to build was the power supply. I’ve attached a diagram that looks something like our circuit without dump resistor to dump charge of the capacitors when we need to service them. We used a hockey puck type of SCR (a type of thyristor) that can take 1000 A continuous or 10 kA pulsed. This may have been an overkill because we found that a maximum of 300 A was needed. However, we may need higher current as we increase the size of the polywell. The capacitor bank was make of 5 X 1500 microFarads electrolytic capacitors that can take a maximum of 450V all connected in parallel. You need some kind of transformer that can step up the voltage from the mains and be able to charge the capacitors within a couple of seconds. That means it shoud be a reasonably hefty transformer. We control the voltage output of the transformer with a Variac on the input side. You need to protect the SCR from back EMF with a diode across it. The diode should be able to take a few amps. The wire diameter about one millimeter and there were 10 turns per former.

Joe’s coil power supply looks like this:

Here is the preliminary bill of material (click for Mouser produce page):

1500 microFarads electrolytic capacitors max 450V

Silicon-controlled rectifier (SCR)

Diode Diode to protect the SCR from back EMF

Step-up Transformer Step-up Transformer


Power Rectifier

Trigger Isolation Transformer

18 AWG magnet wire

100 watt 2KΩ resistor for bleeding capacitor bank

Rack mountable chassis.

Please comment if you notice wrong parts.

Coil Formers

12 02 2010

My shop-mate Stuart machined these coil formers from a teflon rod:

Here is a time lapse video of Stuart machining the  formers on the lathe:

Next we have to drill four holes in each former and connected them with angle brackets.

Coil Former Dimentions

9 02 2010

Here are the final dimensions of the coil former:

%d bloggers like this: