The electrical stimuli stand out as the most widely applied among the physical and chemical aids used in medicine. This has primarily transpired owing to their similarity to natural biological stimuli. Stimulation is a technique in which low-level electrical currents are applied via electrodes for exciting nerve cells or muscle fibers. For treatment by electrostimulation, simple and complex schemes of stimulation must be evolved. To evolve such schemes, manually operated as well as computer-controlled/microcontroller-based programmable stimulators are necessary. These stimulators must have multichannel outputs. In turn, for building stimulators, high-performance, manual/programmable, and low-cost pulse generators are needed. In this chapter, timer IC-based pulse generator is first described for easy understanding. Then microcontroller-based pulse generators are dealt with. Both types of pulse generators permit adjustability of pulse parameters. But in the microcontroller-based pulse generators, the stimulation parameters can be programmed. Important parameters are the frequency of stimulation, width of the pulse, inter-pulse duration, and amplitude of the pulse. These pulse generators provide more convenient, automated adjustments.