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A Vintage HeNe Laser Power Supply

It’s fun to build simple circuits in order to use surplus gear. Here is one example from Popular Electronics, September 1991.[1] There is an array of newer designs using more modern components, but all of the parts below are still available.

“Configured as an astable multivibrator, the 555 oscillates at approximately 500 Hz. The output of U1 at pin 3 is fed to the base of Q1, causing it to alternate off and on in time with U1’s output. The collector of Q1 is connected to the base of Q2. As Q2 turns on and off, a rising and collapsing magnetic field is created in the primary winding of L1 (the auto ignition coil). The rapid switching of Q2 induces a sufficiently high voltage in the secondary of L1 to drive the laser tube.”

Counterfeit 2N3055 transistors are inferior and common on eBay and Amazon. They should be purchased at one of the major distributors (e.g. Mouser, DigiKey).

See the reference below, for full details.

Reference: Gregory Gray, “Build a simple laser power supply,” Popular Electronics p. 32, September 1991. Today, this link works: https://worldradiohistory.com/Archive-Poptronics/90s/91/PE-1991-09.pdf