Experimentonomen´s first argon

So i´ve started on the psu, first off is the passbank/current regulator, this heatsink may be too small but im gonna use a fan that blows alot of air through it.

pics:


The six fets:


The source resistors for the current sense:

^Very impressive work so far Experimentonomen!

Experimentonomen said:

Of cource im gonna add a thermal switch, im not stupid. Sheesh what do you guy think of me ??

Click to expand...

Well it's not in your schematic, nor have I seen mention of it anywhere - so as far was I knew there wasn't one

Heres a schemo of the interlocks:

Heres the preheat timer with lockout so the tube cannot be turned on until preheat have finished, 30-60 seconds depending on the resistor value in the preheat charger circuit. This is both to allow the filament to heat up properly and for the main storage cap to get charged before the laser is enabled.

Pictures of this have been deleted as the mk1 passbank was scrapped, new pictures in future posts.

that looks great!! Ya gotta keep going! If you can get that to work I may need to build a PSU similar to that for my ALC. Loving the soldering on your passbank too, very neat.

Hey, don't give up ;-)

What does your circuit actually do?

I've built a power supply for ion lasers in the past as well, if you are interested, you could take a look at this:

Argonlaser ALC60X

If you are searching for an error in such a circuit, it may be much more easy to test each circuit alone at first. The passbank could be tested without tube, only by a short circuit (or a heater element) in place of the tube and a low voltage supply (for example about 12V DC). Then you could measure the current flow through the short. The tube does act almost like a short circuit, so the current must be limited to the given value independent of the supply-voltage. The Opamp should see the same voltages at both inputs. If this is not the case, he tries to vary the current through the tube until the feedback voltage is exactly the same as the reference value on the other input. If your shunt is for example 0.1 Ohm, then the feedback should be 0.4V at 4A. So if the reference voltage is set for example at 0.5V, the Opamp will change the current flow until the feedback also delivers 0.5V, which is 5A in reality for a shunt of 0.1 Ohm.

If the current limiting of the passbank and the heating-supply are working, you could try to start the tube with a homewound igniter. This is just a toroidal ferrit core with 2 windings on the primary and about 80 windings on the secondary. Then you charge a capacitor of about 470nF up to 400V and discharge it through the transformers primary. With such a setup I started my first Argon-Laser-tube which couldn't start anymore with the internal igniter. With a high voltage probe you could also test if the internal igniter circuit still works. It should deliver about 30kV pulses.

Wish you good luck!

best regards
argon

I am not hooking up the tube until the psu is reliable and puts out the right current.

I decided to have a go with BJT´s as i had two big heatsinks with some on them, so i salvaged all the NPN ones from both(2N3716) and put them one one of the heatsinks, 8 total but one will be used as the driver and the remaining seven till deal with the tube current.

A few pics:

wow that's a HUGE heatsink
nice work, lookin' forward to see it finished :beer:

the mk2 passbank looks even better than the mk1. I agree thats a great heatsink.

Sorry I aint been around to yak with you about argons, been busy helping a few friends this weekend, and other matters.

Argon, thanks for explaining the op amp circuit. helped me quite a bit in the quest for a working argon psu for laserphysics number 2.

timelab, will be paying for that second busted LP in a week or 2.

Cheers,
Ben

Mk2 passbank dident work at all

Working on Mk3 passbank now, using a large IGBT module rated for some 1200V and i´d guess some 50-100A.

I´ve already tested it and it worked like a charm, fully adjustable current from 2A and all way up to 7A which is the most i can get with my dummyload at 140V.

Now i can finally start boxing things up.

Here comes the pics of the new mk3 passbank:

The controller and its power supply:




The main capacitors, however these are getting replaced by two 4700µF 200V ones:



The fan that will keep this cool, the heatsink to which the rectifier and igbt module are mounted to is visible:


What remains is to make the preheat timer and a overcurrent trip.

Anyone up for a video of the regulator in action ?

And heres a video of the laser in operation:

YouTube - A short video of the argon ion laser running

Awesome job.:can: