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Telescope Dew Heater

Telescope Dew Heater

Difficulty
Power

Summary

This project brings together a few Duinotech Modules and some other parts to create a versatile tool. Inspired by the Dew Heaters used on telescopes, it senses ambient temperature and humidity to control a small heater. Not just for telescopes, but anything that needs to avoid condensation.

Features include:

  • Programmable temperature setpoint

  • Temperature target can be set above ambient or dewpoint

  • Settings can be saved to EEPROM

  • Adjustable failsafe heater output to use if sensors are faulty

  • Comprehensive LCD info screen

By making use of as much data as possible, the unit uses no more power than necessary, and can even be run straight from a USB battery pack. It can run a set number of degrees above either dewpoint or ambient temperature. The backlight intensity is also adjustable in code and we've even designed a 3d-printed enclosure that will practically turn it into a professional looking unit.

Materials Required

1Arduino Compatible Temperature and Humidity Sensor ModuleXC4520
1Duinotech Arduino Compatible 2 X 16 LCD Screen Display with ControllerXC4454
1Duinotech UNO r3 Main BoardXC4410
110kΩ Epoxy Dip NTC ThermistorRN3440
110k Ohm 0.5 Watt Metal Film Resistors - Pack of 8RR0596
11k Ohm 0.5 Watt Metal Film Resistors - Pack of 8RR0572
1MOSFET IRF1405 N-Channel 55V 169A TO-220ZT2468
1Duinotech Arduino Compatible Prototyping ShieldXC4482
1150mm Plug to Socket Jumper Leads - 40 PiecesWC6028
139 Ohm 5 Watt Wire Wound ResistorRR3264

Table of Contents

Future Improvements

There are a number of places where the heater could be improved, such as changing the default backlight setting to suit your application, or even making it one of the EEPROM settings. If you need more power, the recommended MOSFETs are capable of at least 5A at 24V. In that case, it would be recommended to run the power supply straight to the MOSFET circuit, and then feed VIN back to the UNO board. That way, the small PCB traces don't have to handle such a high current. An old laptop supply or 12V SLA could be options for this. As mentioned near the start, RCA sockets could be used to standardize the connections to those commonly used on heater bands.

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