Arduino Nano Dew Controller Pro (DIY)

A 3-channel fully automated Dew Controller (DIY project) based on Arduino Nano for telescopes. For $48 or less.

(c) Copyright Robert Brown 2014-2025. All Rights Reserved.
Permission is granted for personal and Academic use only. Code or portions of code may not be copied or used without appropriate credit given to author.

A very popular project with over 48,000 downloads.

There is a new ESP32 WiFi version at https://sourceforge.net/projects/esp32-dew-controller/

The older myDCP2 (two-channel dew controller) is found here https://sourceforge.net/projects/arduinonanodewcontrollerpro/files/myDewController%20v200%202channel/

Features

FULLY AUTOMATIC OPERATION - NO USER INTERVENTION REQUIRED
Windows, Linux, INDI, Bluetooth, Android support for remote control/logging/monitoring
Utilize standard dew straps such as DEW NOT via PWM output, 12VDC
Three tracking algorithms, DewPoint, Ambient and MidPoint with adjustable band offsets
3 independent controlled dew channels
Each dew channel powered by high efficiency MOSFET
3 independent temperature probes DS18B20
Calibration setting for each temperature probe
Controller automatically adjusts power to dew straps (0, 10%, 20%, 50%, 75%, 100%) as required
Supports manual override switches to boost PWM power to 100% for each dew channel
DHT11/21/22 or HTU21D I2C Temp/Humidity sensor support
LCD1602 (or LCD2004) display all settings
Reverse voltage protection on 12VDC input
Key session state values saved in EEPROM for later retrieval
12VDC cooling fan support, speed PWM controlled with RGB LED indicator
LEDS indicate if PWR is on to dew channels (brightness indicates % pwr applied)
Low cost
Data logging of parameters to CSV file
Can be controlled or monitored remotely via USB connection or Bluetooth
Bluetooth wireless support
MOSFET Design for good performance
DO NOT DOWNLOAD SOFTWARE FROM OTHER SITES AS AN EXE/ISO/ZIP FILE - THESE FILES ARE NOT SUPPORTED AND MAY CONTAIN MALWARE

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z80 Posted 2020-07-29

Very well put together with lots of features. Thank you for the hard work put in to this project and for sharing it with us. I've prototyped this with a diymore 2.4" white oled screen which works very well. I like having all the info on a bigger screen. Though since I'm only using two channels at the moment , I may move the screen info around so that channel 1 and 2 are on the same screen, with channel 3 separate (I may use that later) (Thanks to a previous review for the tip about putting a red filter over the screen).
mike1491 Posted 2018-09-09

Brilliant project with excellent support. Thanks for all the hard work Robert
z-field Posted 2017-05-13

Excellent project! I just finished building one and it works great. The author did an excellent job of documenting the project and providing very useful test programs to test each component individually.. The Windows program works well! I did make a few changes. First I did my own circuit board that uses PC board mount RJ-11 4-pin connectors for the temperature probes. I was also able to get all traces on one side without jumpers. I also added an RJ-11 port for the DHT-22 Temperature/humidity probe. I mounted this probe in a plastic cup with the open part pointed down on a coiled phone cord so it can be hung under the top of the mount. This improved the humidity reading considerably. In addition I added a 18B20 temperature TO-92 package to the main board and connected to D2 on the Arduino. I read the temperature of the inside of the box and control the fan based on this reading. I used the MOSFET design so it really doesn't get that hot, but, I didn't want the fan running all the time. I also put a red filter over the display for better night time use, particularly at star parties when near other people as this design can be rather bright. I plan to build the focus controller next.

2 users found this review helpful.