Dimmer switch replace for small appliances like laboratory microscopes, slit lamps, and others as you may think of, Sometimes, the circuit is bad and its taking too much time to find out the problems in the course of diagnose. Find below the schematics diagram for a dimmer switch replace suitable for a low voltage appliances. It is a  Pulse Width Modulation based module suitable for light source of Microscope, Slit Lamps and portable light source. Meanwhile, for small DC electric motor and lots more.

You could actually ask for a replacement dimmer switch from the manufacturer of your product, But if you still have warranty on the appliance, the manufacturers or suppliers would be in a position to help in the repair or replacement.

About the Schematic

The circuit module above consists of three circuits put together. The circuits are 12 volt positive regulator, an oscillator, and a voltage comparator. Other are an integrator, and a driver. The oscillator and the integrator employs an LM324. The comparator is also one of the LM324 package with supporting components.

For this circuit to work, you need a source of unregulated dc power supplies or a battery. Besides, the PSU should be more than voltage of the ic regulator. For example, if the Ic voltage regulator is 12V as shown in the schematic, then, the PSU voltage should be at lear 2.5 volt more than 12 volt. That is, 14.5 volts. Learn more about unregulated power supply unit.

Meanwhile, for more information regarding for specifications; theory; construction; alignment/calibration/configuration; how to use and Bills of Quantity, check here Motor Speed Controller and or DC Light Dimmer (2016_06_01 10_11_06 UTC). 

We can adapt the simple dimmer schematic to control high power load by simply change few components. The main component to change is the Field Effect Regulator (FETs) and the fuse.