Argon Toshiba LHI-106D

[mixedgas]

See attached, although these days we have OP-amps for much better feedback and passbank drive.

I would test it with 5 ohm load in place of the plasma tube.

Requires water cooled pass bank...

I will enhance it with parts to protect it against the ignite pulse.

Pictures of typical water cooled passbank is attached.


This is Lexel model 75, 4-13 Amp 110 VAC PSU for 135 volt tube. 1970s technology, but built like a battle tank.

Schematic is almost exactly the same as Lexel 88 in LASER FAQ except for less passbank transistors (6) , tapped input transformer, and a few resistor values are different.


Steve

[mixedgas]

Remember cathode must heat for 30 seconds with fans running before applying B+ to laser tube and firing igniter.

Steve

[Methelina]

See attached, although these days we have OP-amps for much better feedback and passbank drive.

I would test it with 5 ohm load in place of the plasma tube.

Requires water cooled pass bank...

I will enhance it with parts to protect it against the ignite pulse.

Pictures of typical water cooled passbank is attached.


This is Lexel model 75, 4-13 Amp 110 VAC PSU for 135 volt tube. 1970s technology, but built like a battle tank.

Schematic is almost exactly the same as Lexel 88 in LASER FAQ except for less passbank transistors (6) , tapped input transformer, and a few resistor values are different.


Steve

Interesting solution, and yeah like a tank without mercy

Im now working on enhancing this version to the tube data you told before. I think its a good compromise betwixt the stability and complexity:

Soon i will make a new fully remade schematics...

I will add the Fan and lot of protections same as pi-filter and so on.
The linear pass bank i think will be great to feel on the large alum plate covered by fans. Making the water cooling systems will be too complex for the very beggining. I though about FCA-820 or Tarzan, but its hard to get in modern days or it costs too much for my poor country I have a lot of 220v fans from the power control systems so I can use them.

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Sure about preheating the tube!

[mixedgas]

Make sure you have C7, usually it is 0.1 uf to 1 uf 600 volt metal can type mica capacitor and mounted close to the tube. It bypasses the ignitor spike from the electronics. Igniter spike is ringing waveform at 40 Khz to 1 Mhz depending on model.
I doubt your ignitor board needs the T4 boost voltage. It looks like a GLG-3030 style or Spectra Physics 163 style self terminating ignitor . It would be wise to check.
When the plasma lights the removal of electrons will cool down the cathode, it is wise to bring the cathode voltage and tube current out for easy measurement.



Steve

[Methelina]

Make sure you have C7, usually it is 0.1 uf to 1 uf 600 volt metal can type mica capacitor and mounted close to the tube. It bypasses the ignitor spike from the electronics. Igniter spike is ringing waveform at 40 Khz to 1 Mhz depending on model.
I doubt your ignitor board needs the T4 boost voltage. It looks like a GLG-3030 style or Spectra Physics 163 style self terminating ignitor . It would be wise to check.
When the plasma lights the removal of electrons will cool down the cathode, it is wise to bring the cathode voltage and tube current out for easy measurement.



Steve

Ouch, ok thanks, I will check them and thanx for C7 !
Btw, what about AOM i showed before?

[mixedgas]

The Lexel Model 65 supply is air cooled. It uses 12 2N6259 to-3 cased passbank transistors on a "tunnel" heatsink cooled by two big fans. We have had some luck replacing 2N6259 by linear FET in TO-247 package, mounted close together to prevent thermal runaway, and cooled by water. I seem to remember from working on Lithuanian lasers that there was European / Russian NPN starting with BU part number from TV Horizontal Output that was even more capable then 2N6259. I know Sam changed the design to 2N3055, but that is not a great NPN in terms of C-E voltage, Vce0, 60V for 2n3055 against 250v for 2N6259. The idea is to never have more then 20-30 volts across the passbank transistors when the tube is lit. If that occurs, change transformer turns etc. Ideal situation is around 8-10 volts. At low currents the voltage across the passbank will be high. We always try to start the laser plasma at medium or high current to protect the transistors from start-pulse.

BU-208 in TO-3 or similar....???????

Steve

[mixedgas]

I need to dig in my spare bedroom with forklift or front end loader to get to the AOM driver module. It is in "long Term Parking". I will try tonight.

Steve

[Methelina]

Coming soon, after I use a forklift to clean out the spare bedroom where the driver is at the bottom of the storage pile.

Steve

Aheheheh, Ok!

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And sorry for my newbiestery, I never has a deal with gas lasers before but what is a "Self Terminating Ignitor"?

[mixedgas]

Ignitor board senses when voltage across tube > 150 volts or so and starts pulsing. When tube is lit, voltage goes to 90-110VDC and ignitor stops. Some ignitors are controlled by the PSU and do not automatically stop.
~
See attached. By my standards you really know what you are doing in Electrical Engineering... No problem, your asking good questions. NOT A NUBIE...
~
Your TOSHIBA looks very much like a NEC / SHOWA Ion Laser head, may be a second source / clone in Japan.
~
Steve

[Methelina]

Ignitor board senses when voltage across tube > 150 volts or so and starts pulsing. When tube is lit, voltage goes to 90-110VDC and ignitor stops. Some ignitors are controlled by the PSU and do not automatically stop.
~
Your TOSHIBA looks very much like a NEC / SHOWA Ion Laser head, may be a second source / clone in Japan.
~
Steve

Yay! thanks a lot! Now it making sense, need to improve my scheme by this controling chain!

See attached. By my standards you really know what you are doing in Electrical Engineering... No problem, your asking good questions. NOT A NUBIE...
~

I try to do my best! "Well, we must live and learn."© Dostoevsky, Fyodor / Crime and Punishment.