tag:blogger.com,1999:blog-4541271552202931674.post8546728350504997977..comments2024-03-24T17:03:06.150+00:00Comments on Blackwater Skies: A Cheap Multi-Channel Dew Heater ControllerUnknownnoreply@blogger.comBlogger13125tag:blogger.com,1999:blog-4541271552202931674.post-9747930078488515392016-11-03T13:52:16.968+00:002016-11-03T13:52:16.968+00:00Hello Ian
Thanks for sharing this. One question. ...Hello Ian<br /><br />Thanks for sharing this. One question. I think these dimmers operate at a PWM frequency of 20KHz. Any risk of electromagnetic interference with the imaging equipment? <br /><br />In that case it would be advisable to shield the wiring and the heating elements too... Alternatively, there is a way to lower the PWM frequency. Google for: led-dimmer-pwm-hack.<br /><br />RegardsSaltyDoghttps://www.blogger.com/profile/00750128159678198238noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-3402644861616112812016-09-28T14:46:28.478+01:002016-09-28T14:46:28.478+01:00You are correct that the LED will always be "...You are correct that the LED will always be "On" in this design. The LED gets brighter or dimmer depending on the setting of the controller, so you can figure out (roughly) how much heat is going to be generated. I just turn down the controllers on any unused channels. If you want to do something more sophisticated, perhaps take a look at current sensing circuits, the output of which can be used to drive an LED and would likely do what you want. Try here for example: http://cds.linear.com/docs/en/application-note/an105fa.pdfAnonymoushttps://www.blogger.com/profile/11513960040878129254noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-57042488137756663202016-09-22T19:58:02.444+01:002016-09-22T19:58:02.444+01:00Hey,
I have a question, based on your deluxe diag...Hey,<br /><br />I have a question, based on your deluxe diagram, it appears that the LED hookup closes the circuit loop, so even if you don't plug in a heater, all lights with be lit (as long as a power is supplied).<br />If i'm reading that correctly, then, how would you be able to hook up the LED, so that it turns on only when a heater strap is connected?Eugene Beyginhttps://www.blogger.com/profile/05421554757947275468noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-46650304535568175362016-09-20T03:46:17.276+01:002016-09-20T03:46:17.276+01:00wondering.. what say you about a 3 channel dimmer?...wondering.. what say you about a 3 channel dimmer? looks like 3a per channel... to run 50mm guide scope. 80mm scope. and lazar for alignment of scope to sky... thats only a few mins of time.. <br />i can post link if wish.. to see what iam askin about.. <br />thank you for any help on this... <br />PhilAstroimagerhttps://www.blogger.com/profile/11306392384021379908noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-59190492611594208792016-04-22T22:29:56.426+01:002016-04-22T22:29:56.426+01:00That makes sense then. Thank you for providing the...That makes sense then. Thank you for providing the information and allowing myself to become more educated. I ended up using 16.1 ohm per m through 16v, to achieve 0.27 w per cm on my 75 cm band. At 18v it works out to 0.36w per cm. Tested on the sct today and works great. Thanks again Anonymoushttps://www.blogger.com/profile/07284216702559498641noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-79744807651002790042016-04-19T22:47:30.211+01:002016-04-19T22:47:30.211+01:00No. The output voltage should be pretty much the ...No. The output voltage should be pretty much the same as the input voltage, so if you're putting in somewhere between 12-13V, you should be getting 12-13V out.<br /><br />The variation in power is due to Pulse Width Modulation (PWM). Basically the dimmer control switches the current on and off rapidly and repeatedly. As you turn the dimmer to the lower power setting, the circuit spends more time in the off state than on, whereas turning it up means the opposite happens.<br /><br />This power cycling is the best way to dim an LED light source as LEDs will only operate in a fairly narrow range of voltages. Drop the voltage too much and the LED goes out rather than dimming, push it too high and it will burn out. By switching the LED on and off rapidly (faster than you can detect by eye), it appears dimmer to the human eye due to persistence of vision, but to something like a fly's vision it would appear to be flickering on and off.<br /><br />A dew heater band will work at a wide range of voltages though, so we could simply reduce the voltage using a potentiometer or other arrangement of resistors to cut the power. That's pretty inefficient though as you're just turning the excess power to heat in the resistor, wheras PWM is much more efficient (and the calculations are easier) since the voltage remains constant but the power cycles on and off.<br /><br />Due to the rapid cycling, your multi-meter will show an output voltage close to the input voltage. If you used an oscilloscope to measure the output, you'd see a regular cycle of pulses where the voltage rises from 0V to 12V and back to 0V again.Anonymoushttps://www.blogger.com/profile/11513960040878129254noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-38871168937771678542016-04-19T21:50:35.335+01:002016-04-19T21:50:35.335+01:00I just built a control box using the exact same di...I just built a control box using the exact same dimmer. I'm only able to get 12.2 -12.6 v variability. Is it supposed to be more?Anonymoushttps://www.blogger.com/profile/07284216702559498641noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-80792287432678032152015-12-15T19:09:51.324+00:002015-12-15T19:09:51.324+00:00Read my other article about making heater bands fo...Read my other article about making heater bands for details of how to calculate the current draw of a band (or set of bands). If you have purchased commercial ones, the documentation may tell you, or failing that measure the resistance and plug the figures in to the spreadsheet linked to in the article:<br /><br />http://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater.htmlAnonymoushttps://www.blogger.com/profile/11513960040878129254noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-6859275038883093682015-12-15T17:52:57.872+00:002015-12-15T17:52:57.872+00:00This is a great project and really simple, thanks ...This is a great project and really simple, thanks for sharing.<br />Does the 12V power supply neede to have a certain power output?Anonymoushttps://www.blogger.com/profile/13019308581861003170noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-80379511565464070852015-09-24T15:30:36.416+01:002015-09-24T15:30:36.416+01:00If you know you will not exceed 0.8A then a 1AA fu...If you know you will not exceed 0.8A then a 1AA fuse should work, but 1.25A would give you a bit of headroom. There is no real downside to having the lower fuse rating to start with, provided you have a spare in case it does blow. Go too high and you could have problems with overheating in case of a short, so dont use a 13A or similar.Anonymoushttps://www.blogger.com/profile/11513960040878129254noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-65666527650661431512015-09-24T12:46:31.343+01:002015-09-24T12:46:31.343+01:00HI
i am currently buying the components to make t...HI<br /><br />i am currently buying the components to make the larger box version of the dew heater for my obsy. One question though - as i plan (as you have) to put a fuse in per dimmer, what amp fuse should i use? As each dew band should not be outputting more than 0.8 amps, should i use 1 amp fuse? i think you can get 1.25 and 1.5 amp too. i guess i am asking what amount of Torrance i should give my dew heaters. <br /><br />thanks <br /><br />AndyAnonymoushttps://www.blogger.com/profile/05223979182804252639noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-16045310606292852202014-10-02T11:46:08.703+01:002014-10-02T11:46:08.703+01:00I haven't done this project, and have no plans...I haven't done this project, and have no plans to at the moment. The Arduino is one I had from a previous home-made guiding interface for a basic DC motor mount that I no longer use. I am planning to create a stepper motor focuser using the Arduino at some point when I get time.<br /><br />Here is a link to a mega-thread on using Arduinos for dew-heater control:<br /><br />http://stargazerslounge.com/topic/162586-arduino-dew-heater-control/<br /><br />Here is another shorter, more recent one:<br /><br />http://stargazerslounge.com/topic/225528-arduino-dew-controller-feature-rich/Anonymoushttps://www.blogger.com/profile/11513960040878129254noreply@blogger.comtag:blogger.com,1999:blog-4541271552202931674.post-68896380440511480262014-10-02T10:24:48.227+01:002014-10-02T10:24:48.227+01:00Hi,
I have just built something similar and would ...Hi,<br />I have just built something similar and would like to know how you integrated the Arduino board into the control of it, I want to do that with mine but am a complete novice with these boards, I have no idea how to get the Arduino board to control my dew controller, I also used exactly the same dimmers that you did.<br /><br />Regards<br />OllyOllyhttps://www.blogger.com/profile/15763802864259314545noreply@blogger.com