SHT4x temperature & humidity sensor

Heating element integrated in PCB design

Optimized for Raspberry Pi HQ camera

Short cable connections — no complex wiring

AMASCHR01 – Heater Ring with Sensor

The AMASCHR01 is a heater ring with an integrated SHT4x temperature and humidity sensor for precise closed-loop heating control, keeping the optical dome clear during cold and humid nights.

Optimized for use with Raspberry Pi HQ cameras, its design allows short, direct cable connections between the heater, sensor, and camera board — eliminating the need for complex wiring back to the Raspberry Pi.

Key Features

• SHT4x Temperature & Humidity Sensor: Precision-calibrated sensor enables accurate dome monitoring and automatic heating regulation.
• PCB-Integrated Heating Element: The heater is part of the board design — no soldered resistors, resulting in even heat distribution and improved reliability.
• Air Circulation Holes: Board cutouts allow airflow around the camera module, helping maintain stable internal conditions.
• Optimized for Raspberry Pi HQ Camera: Designed to sit directly around the camera module, enabling smart and compact cable routing.
• Simplified Wiring: Short cable connections replace complex long-distance wiring to the Raspberry Pi, improving reliability and simplifying assembly.

Specifications

Sensor (SHT4x)

• Supply voltage: 3.3 V
• Interface: I²C
• Connection: Soldering tabs

Note: Although the SHT4x is a temperature and humidity sensor, it is mounted directly on the heated surface. Therefore, it measures the surface temperature of the heater ring, not the ambient air temperature inside the dome. This is by design — it enables accurate closed-loop control of the heater output.

Heating Element

• Maximum supply voltage: 12 V (with PWM/PID control), 5 V for permanent/continuous unregulated power
• Resistance: ~5.8 Ω
• Maximum power at 12 V: ~25 W
• Power at 5 V: ~4.3 W
• Heating capability: Up to ~40 °C surface temperature at full power (25 W), which is excessive for normal operation. Recommended operating temperature is around 15 °C.

Recommended Control

Optimal heating control is achieved using PWM with a PID controller, using feedback from the on-board SHT4x sensor. This ensures stable, efficient dome heating without overshooting.

The heater ring itself does not contain any control logic. It requires a host system (e.g. Raspberry Pi) running the heating control software with the PID regulator. The host system reads the SHT4x sensor data and drives the heater via PWM output accordingly.

Installation

Compatibility

Compatible with Raspberry Pi HQ camera modules and the AMASC01 AllSky Camera.