DIY Dew Heater Controller

[AndyThilo]

Hi

Looking for a cheap single channel dew controller for my planetary setup. I have the strap already so just need the controller. I believe controllers are PWM? Would any of these suit? It'll be run from a basic 12v distribution, probably fused powerpole. I don't want to spend out on another Pocket power box.

https://www.amazon.co.uk/s?k=12V+PWM&ref=nb_sb_noss_2

I'm pretty skilled with soldering and wiring so no issues with a DIY solution. 

Cheers

Andy

[wormix]

I copied this for my simple 2 channel - works absolutely fine 

https://www.blackwaterskies.co.uk/2013/05/a-cheap-multi-channel-dew-heater-controller/

 

Edited October 10, 2020 by wormix

[fozzybear]

+1 as well as @wormix I am planning a second box but using these will see if they work as they are compact and have a switched rotary dial. I will be fitting an inline fuse. my dew strap only draws 7 watts 0.6 amps so should work.

https://www.amazon.co.uk/Youmile-Controller-module-control-controller/dp/B07XTFLCWN/ref=sr_1_4?dchild=1&keywords=12V+PWM&qid=1602351428&sr=8-4

albeit mine are from a different vendor from the .Fr site

[stash_old]

+1 as well for @WORMIX solution but replaced knob with cheap (<£5 5v stepper) and a nano with Moonlite ino code - runs under Indi (serial only) or Ascom and/or Moonlite App but I use Nodered = remote dew heater. +1 for inline fuse.

[AndyThilo]

Looks good, does the Nano allow auto control with a thermistor attached as well? 

[symmetal]

7 hours ago, stash_old said:

+1 as well for @WORMIX solution but replaced knob with cheap (<£5 5v stepper) and a nano with Moonlite ino code - runs under Indi (serial only) or Ascom and/or Moonlite App but I use Nodered = remote dew heater. +1 for inline fuse.

If you're already using a nano, wouldn't it be easier to drive a mosfet from one of the nano PWM pins as a dew controller. You can then do away with the stepper motor and the separate dew controller modules. If you change the corresponding timer prescalers for the PWM pin(s) used you can have a 31kHz PWM frequency instead of the default slow 490Hz, and then if required, a small filter on the 12V going to the mosfets will remove any PWM switching pulses from affecting the main 12V distribution. 🙂

Alan

[stash_old]

7 hours ago, symmetal said:

If you're already using a nano, wouldn't it be easier to drive a mosfet from one of the nano PWM pins as a dew controller. You can then do away with the stepper motor and the separate dew controller modules. If you change the corresponding timer prescalers for the PWM pin(s) used you can have a 31kHz PWM frequency instead of the default slow 490Hz, and then if required, a small filter on the 12V going to the mosfets will remove any PWM switching pulses from affecting the main 12V distribution. 🙂

Alan

No - for me its a simple ready made cheap solution(easy replaced)  with 2 wires in/out that I can buy ready made and the Moonlite code in the nano is used unchanged. Plus if needed I can just turn the stepper manual if the Nano packs up. Works for me 🙂

[wormix]

16 hours ago, stash_old said:

+1 as well for @WORMIX solution but replaced knob with cheap (<£5 5v stepper) and a nano with Moonlite ino code - runs under Indi (serial only) or Ascom and/or Moonlite App but I use Nodered = remote dew heater. +1 for inline fuse.

You’ve piqued my interest, got any further details?

 

ta

[stash_old]

3 hours ago, wormix said:

You’ve piqued my interest, got any further details?

 

ta

Nano code based on Roberts Focuser (just moves Stepper)    https://sourceforge.net/projects/arduinofocuscontrollerpro/  later modified to use Accelstepper/MQTT to talk to ESP8256 via wifi  and Nodered.  So I suggest starting with Roberts Open source code! 

Later used this code as starting point

// Moonlite-compatible stepper controller
//
// Uses AccelStepper (http://www.airspayce.com/mikem/arduino/AccelStepper/)
//
// Inspired by (http://orlygoingthirty.blogspot.co.nz/2014/04/arduino-based-motor-focuser-controller.html)
// orly.andico@gmail.com, 13 April 2014
//
// Modified for indilib, easydriver by Cees Lensink
// Added sleep function by Daniel Franzén

 

 

one of these (or similar)   https://www.ebay.co.uk/itm/12V-24V-LED-Strip-Light-Dimmer-Switch-8A-Voltage-Regulator-Adjustable-Controller/283995378247?hash=item421f719247:g:8MkAAOSwMXpfTMmY 

5v geared stepper and board  5V-4-Phase-Geared-Stepper-Motor-W-ULN2003-Driver-Board-28BYJ-48

A coupler to join dimmer shaft to stepper  shaft  https://www.ebay.co.uk/itm/Flexible-shaft-coupling-joint-Stepper-Motor-Coupler-Connector-for-3D-Printer-CNC/124270383132?hash=item1cef17901c:g:T7YAAOSwn2NfGUtM                                              

Home made stepper bracket which used Dimmer cover screw points to attach itself

Std Old version Nano(replaced by ESP8256) and a enclosure (I recycled old PC power brick). Note Nano version was orig connected to a Windows box (now replaced) to use Moonlite Windows App or Roberts App via USB COM port.

 

Before Nodered I just used std Moonlite Windows App or Roberts Windows focuser Testing App (early version RC ?) to stepper x steps to positions I had worked out  - simplest method no coding changes needed.

Later  Moonlite App replaced with a very basic and simple Nodered App (see screen print attached) talking MQTT using old RPI3 running MQTT server (runs other things as well - Temp/Hum sensors inOTA and Obsys plus else where) - I dont give out my Nodered code as it has in house and other security details but it was simpler enough.

Biggest problem Moonlite inbuilt Temp sensor coding which just polls too often - had to cheat and reply with preset temp all the time. I did use a very simple Arduino coded voltage/Pwm measure circuit but it proved a pain but worked.

 

 

 

                                        

Edited October 11, 2020 by stash_old