Feature: 1. The product is Schumann wave 7.83HZ extremely low frequency generator. With high accuracy and stability 2. This is a rechargeable model, small and portable in size, rechargeable. Free you 20CM / 7.9in charging cable 3. Using a new optimized circuit design and gold‑plated launch circuit! With wide applications, generate wave signal for experimental development, to control the motor driver, generate adjustable pulse for MCU and to control the relevant circuit (PWM dimming speed application etc). 4. Rechargeable type creates a greener world, compact size makes it easy to carry. Nearly without voltage ripple, enabling more accurate output frequency 5. The charging current is 250ma, the product can be fully charged in about 6 hours, the working current is about 7MA, and it can be used for about 200 hours (168 hours a week) when fully charged. Specification: Item Type: Schumann Wave Pulse Generator Module.Power Supply: 5V micro-usb for Android interface charging cableBattery: 3.7v lithium battery, capacity 850mahUseTime: The charging current is 250ma, the product can be fully charged in about 6 hours,the working current is about 7MA, and it can be used for about 200 hours (168 hours a week) when fully charged. Package List: 1 x Module1 x USB Line 1 x Screwdriver