A stimulator with an improved circuit and with durable components so that it is of better quality and more reliable in use. The battery compartment is modified to make it easier to insert and change the battery. Besides, a battery low indicator is added into the unit which reminds the user to change a new battery when this lights up. 4 channels, equipped with 3 waveforms, high-low output selections, 0-100 Hz or 10- 10000 Hz adjustable frequency as well as point locator and stimulation probe. It is a fully-featured unit and completed with accessories.