Radiomaster ER4 4-Channel ELRS Receiver

The ER4 has proven quite reliable in many combat robots in the past few years, and its unique thin form factor makes cramming it into tight spaces a breeze. The ER4 is the stock receiver for the DRV Drum Spinner Kit. 

You can learn more about Open Source ELRS also known as the ExpressLRS protocol, here. 

This receiver will ONLY work with an ELRS radio, or one that has an ELRS module installed. The Radiomaster Pocket ELRS is the most common and best price-to-performance radio available. 

From Radiomaster's site: 

Features

• Based on the Revolutionary ExpressLRS System
• High performance, high reliability, flexible configuration, low latency, and strong link quality
• Support 4 PWM Channel
• Optimized ground up PCB design
• Automatically voltage telemetry of external battery voltage or built-in receiver voltage
• Supports Wi-Fi updates and WEBUI configuration
• High quality 2.54 mm connector
• Standard 15 cm High Sensitivity Antenna
• For any application that requires a small or lightweight receiver
• Compatible with all 2.4GHz ExpressLRS modules and transmitters with built in 2.4GHz ExpressLRS

Specification

• Item: ER4 2.4GHz ELRS PWM Receiver
• Power supply: DC 4.5 - 8.4V
• Antenna type: 15cm high sensitivity antenna
• Wireless protocol: ExpressLRS 3.3.0 pre-installed
• Output channel: 4CH PWM
  
• Telemetry power: 10mw
• Battery voltage detection range: DC 4.0- 35V
• Weight: 3.0 grams
• Dimensions: 30*15*5mm
• Firmware: Device Category: Radiomaster 2.4Ghz / Device: RadioMaster ER4 2.4GHz PWM RX