PID control - a suitable test system?

[suethechemist]

I hope to use the PID controller to stabilize a voltage source associated with a laser - the voltage drifts slowly over time (I estimate the drift to be ~2.5 V/hr) causing a change in the output wavelength of the laser, which is unacceptable for our experiment. Can anyone suggest a suitable system to test the controller on before I actually hook it up to the laser? I know (some of) my benchtop power supplies show a similar drift over time. Am I being too cautious? Are spurious outputs from the controller likely?

[johnsold]

In the January 6, 2005 edition of EDN magazine one of their "Design Ideas" was a simple circuit for a laser diode simulator which uses two resistors and one transistor. Laser diodes are quite sensitive to transients (sensitivity is proportional to the cost of the diode 🙂 ). I highly recommend testing any controller/power supply with a simulator first.

Lynn