Instructions for Wiring AC-Input HeNe Laser Power Supply Bricks

This is detailed info on wiring 115/230 VAC input power supply bricks with ballast resistor(s) and optional tube mounting brackets for use with the high power HeNe laser kits including stabilized. The diagrams below show the general arrangement. It is critical that the polarity be correct. The diagrams also show the polarizing beam sampler that would be required for the stabilized laser kits (or for other experiments).

Note that these power supplies may have an Alden connector for the tube. A mating connector will be provided in that case. If there are only the high voltage leads, there will be no Alden connectors.


Wiring the power supply

  1. Determine what color code is used for the AC wiring of the brick in the kit. This is critical! I will generally provide this information via email or an eBay message. There is some info at Sample Color Coding of AC Input Power Supply Bricks that covers most types/manufacturers. If not included there and it's not obvious, please contact me before doing something you may regret.

  2. An appropriate fuse should be included in the HOT wire to the power supply. This is most often a 1 amp medium or normal blow fuse. It can be permanently attached as the fuse should only blow if something bad happens inside the power supply. A suitable fuse will be included with the kit, probably already attached and insulated.

CAUTION: ALL INPUT WIRING MUST BE SECURED USING SOLDER, WIRE NUTS, OR A SUITABLE CONNECTOR. DO NOT JUST WRAP THE WIRES TOGETHER. INTERMITTENT CONNECTIONS BLOW STUFF.

Installing the tube

Examine the mirrors of the laser tube to determine the end for the main beam. Most of these tubes from the output from the cathode-end but it can come from either end. It can usually be determined easily without powering the tube since there will be an AR coating on the output-end mirror which appears blue-ish in reflected light. However, in rare cases, there may be an AR coating on both mirrors.

Wiring using the brackets:

  1. If the output is from the cathode-end of the tube (as it is in most cases), there should be hole already drilled in the cathode-end bracket so the photons can escape. ;-) If not, it is possible to swap the two brackets or drill a hole. But the bracket with the red wire and ballast resistor MUST have the anode-end of the tube.

  2. Remove the adjustable attenuator plate (if present) from the original anode-end mounting bracket (if present) by unscrewing the hex-head screw. This plate can be used for other purposes like as a beam sampler.

  3. Attach the anode and cathode mounting brackets to a secure surface spaced to permit the tube to just fit between them. For testing this step can be postponed. Depending on how the tube will be used, one or both brackets may be trimmed to free up space between them.

  4. Flip open the covers on the mounting brackets by pulling back on the locking tabs.

  5. CAREFULLY lay the tube ends on the mounting brackets paying particular attention to polarity: The positive has the fat red wire and receives the anode (glass)-end of the tube; The negative has the fat black and receives the cathode (aluminum can)-end of the tube. Make sure the anode-end bracket isn't too cockeyed to permit the beam from getting out of the hole. :) Make sure the tip-off (exhaust tube) at the cathode end clears the structure of the bracket.

    CAUTION: THE TUBE MAY APPEAR TO WORK WITH REVERSE POLARITY BUT WILL PROBABLY BE RUINED IN A FEW MINUTES. Gently press the covers in place so they click and are secure.

    Take care to avoid stressing the fat red wires to the ballast resistor. If either breaks off, it may be necessary to replace the ballast resistor.

Wiring using tube clips (if included, mostly for the various stabilized lasers where special mounting may be desirable

  1. Cut the fat wires near the mounting brackets (retaining the ballast resistor) OR use the separate fat red wire and ballast resistor(s) that may be included.

  2. Solder tube clips to the wires.

  3. Carefully route and secure the wires so they don't stress the conections at the tube.

  4. Gently press the clips onto the tube mirror mounts making sure they go to the correct mount: The positive has the fat red wire and receives the anode (glass) end of the tube; The negative has the fat black and receives the cathode (aluminum can) end of the tube. Make sure the anode-end bracket isn't too cockeyed to permit the beam to get out the hole. :) Make sure the tip-off (exhaust tube) at the cathode-end clears the structure of the bracket. CAUTION: THE TUBE MAY APPEAR TO WORK WITH REVERSE POLARITY BUT WILL PROBABLY BE RUINED IN A FEW MINUTES.

WARNING: THE VOLTAGE BETWEEN THE ANODE AND CATHODE OF THE LASER TUBE MAY BE GREATER THAN 5,000 V WHILE STARTING AND GREATER THAN 1,000 V WHEN RUNNING. TOUCHING THIS WILL PROBABLY NOT BE LETHAL BUT YOU WILL FEEL IT AND PERHAPS TOSS THE ENTIRE RIG ACROSS THE ROOM. :( SIGNIFICANT CHARGE WILL REMAIN ACROSS THE TUBE AND POWER SUPPLY FOR SOME TIME AFTER INPUT POWER IS REMOVED. USE A CLIP LEAD ACROSS THE TUBE TO DISCHARGE BEFORE TOUCHING ANYTHING TO BE SAFE.