Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

lenscap

Do 12V sparks damage electronics?

Recommended Posts

My diy Onstep GoTo controller is basically an Arduino Mega 2560 with a RAMPS 1.5 shield, rated for 12V normal, 20V max & uses about 2A max.

It is powered from a 12V car  battery. The lead has crocodile clips at the battery & connects to 5A screw terminals on the RAMPS.

When I "power-up" by connecting the clips there is a spark at the terminal. This is expected, but does the sparking reduce the life of my electronics?

If so is there a cheap/simple way to reduce or prevent this?

I know I could put a switch in the lead but I assume the sparking would then happen inside the switch, making no difference.

 

Share this post


Link to post
Share on other sites

The spark certainly can damage electronic circuitry, I would put a 100 nano farad capacitor (non electrolytic) rated at around 50 volts across the circuit to be powered and if using a switch put one across that too. You could also add a large value inductor in series with the supply as well, its worth looking at  auto accessory shops in the sound system department for an off the shelf solution too.

Alan

  • Thanks 1

Share this post


Link to post
Share on other sites

The sparking is caused by the connection happening relatively 'slowly'. Switches like toggle or rocker design have spring mechanisms to ensure the connection or disconnection happens as quick as possible to minimise sparking. At the moment of closure the current drawn will normally be much higher than its normal operating current as capacitors in the electronics charge up. The sparking itself doesn't cause damage to the electronics but if you're tentative about attaching the clips the circuit may be made and broken several times during connection causing excessive sparking and several current surges. The repeated current surges may cause some components to fail more quickly. Putting a good toggle or rocker switch will be beneficial in the long run. The spark itself will cause erosion of the actual crocodile clips and battery connector as the spark is molten metal from the connection like a mini arc welder. Another effect is radio interference caused by the sparking which may cause momentary signal loss if picked up by cables or on your wi-fi. :smile:

Alan

Edited by symmetal
  • Thanks 1

Share this post


Link to post
Share on other sites

Thanks for the good advice guys.

I will be fitting a rocker switch and a choke in the +12V line.

Share this post


Link to post
Share on other sites

If you put a choke in the 12V line you will need to connect a flyback diode across it. It's the same reason reverse biased diodes are connected across relay coils and DC motors. Without it when you turn off the switch, the choke (or inductor) will generate a high reverse voltage across itself in order to try and keep the current flowing, supplied by the magnetic energy which was stored in the inductor. This voltage can be much higher than the supply voltage and can easily damage electronic components. It would also cause a bigger spark to develop across the switch when it opened.

An RC Snubber can be connected across the switch to reduce arcing instead but these are only really needed when using highly inductive loads.

For your use just a fast acting switch on it's own will suffice. In 20 years or so when the contacts have burned away so much they are unreliable, you can replace the switch. ?

Alan

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By angryowl
      This will be a thread detailing some of the changes and additions I will be doing to my ASC/Weather Station project. This is version 2.0 as I'll be making some very big changes from the initial project and I think continuing on in the existing thread would not have made much sense.
      So, I still want to use an APS size sensor as after seeing the quality and light capturing capabilities of the now defunct Opticstar DS-616C XL camera and Meike lens I simply cannot go back to using a smaller lens/sensor combination. One thing is certain, I won't be paying £400 or potentially more for another APS astro sized camera so with that in mind I plan on heavily modifying a Nikon D50 DLSR and use the same lens. I chose the D50 primarily due to it having a CCD sensor (ICX453AQ) very close in specs to the one in the Opticstar (ICX413AQ) and the fact that I got a hold of a fully working body for £25.
      Now there's a few issues with going down the DSLR route which I plan on addressing as follows:
      The oversized camera body can be stripped down to bare essentials and fitted in the existing case with some moving of parts around Uncooled, the sensor is quite noisy so to cool it I plan on using the existing Opticstar enclosure with the TEC and hopefully get it purged with Argon to avoid dew formation. Also, since the box will need to be completely sealed to achieve this, there's simply not enough room inside for the main board to which the sensor connects to. The only way around this is using an 39pin 150mm long FPC extension which I managed to find and will be arriving shortly. This means I can have the sensor completely sealed with enough slack in the connection to place the mainboard anywhere I want. The D50 uses the NEF file extension as a "RAW" file format but it's not truly RAW and a heavy median filter is applied to all long exposure images to smooth out the noise. It works great for day to day shots, but in an application such as mine it'll most probably eliminate or severely affect my stars as most of them at the FL I'll be using the camera at will be a few pixels across and the Nikon median filter is very aggressive with such small features. The way around this is what's commonly known as Mode 3 on Nikons. Nikons have a additional Noise Reduction mode which takes the long exposure light first then straight after an equal length dark with the shutter closed, then applies the dark on the light and you get a further noise reduced image which again works very well, but not so much for AP. With mode 3 you essentially have the NR feature on and take an exposure but then immediately shut down the camera after the light has finished exposing. What this does is it causes the camera to dump a REAL RAW image onto the SD card without applying the median filter OR the Noise Reduction process. This obviously results in a much noisier image as expected, but all the stars will still be there and the image in this way can then be dark-subtracted and processed to my liking. I'll post some test shots I've taken to illustrate this. The D50 uses a hybrid shutter, both the CCD electronic shutter and mechanical shutter are used depending I think on the exposure length. If a high enough exposure is used, from what I understand, one can use exclusively the electronic shutter, but for longer exposures the shutters work in conjunction. Now I know the ICX413AQ in the Opticstar is more than capable of taking long exposures solely with its electronic shutter despite the fact that in its datasheet they recommend a mechanical shutter for proper use. So, my thinking is since the D50's sensor is similar to the ICX413AQ the only thing preventing the camera from being able to take any exposure using exclusively the electronic shutter is that its mechanical shutter is in the way and I don't think that the camera would prevent the CCD electronic global shutter itself to still open and close when required. However, this is all a theory at the moment and the only way to confirm it is to test the camera with the sensor outside when the FPC cable arrives. More on this later... In terms of capture software available, the D50 is actually very poor and I could only get digiCamControl to see and control the camera via USB. But I won't be using this as when the camera is hooked up to the PC its SD card is identified as a storage drive and the camera can be used as it would normally with the images appearing on the drive after being written to the SD! Since I'm using my VB app to process the images I would just point the app to that folder and should work. That's all I can think of for now but if and when new ones come up I'll add them here.
      Next I'll be describing some of the other changes planned.
    • By bottletopburly
      So  my birthday just past so money to splash on astro stuff , i will have my 1000D modded by juan at cheapastrophotography and also have ordered an autofocuser from deepsky dad https://deepskydad.com/autofocuser i know they can be done DIY but this is a neat package  and costs about the same as a SW autofocuser and a hitechastro focusmaster and i`m no electronic wizard and pavel seems to have a good product and works with ascom and confirmed it works with APT i will update in a few weeks time when hopefully i will have received and tried out . 
       
    • By arun289
      Hi,
      I would like to share my design of a smart barn door tracker. It is a simple to build isosceles barn door tracker with tangent error correction through a Arduino micro-controller. I have shared all the details about the tracker including the mechanical design, electrical circuit and the software source code here:
      https://barndoor.spa...ference-design/
      If you are interested in the math and other details about a barn door tracker, more details are there in the blog. Also find an online calculator which helps in calculating various parameters while designing a barn door tracker. The blog is here:
      https://barndoor.space/

       
      M46 and M47 shot with this tracker.
      135mm lens, ISO800, 15sec X 200 subs (50 minutes) exposure. Cannon 500D.

      Comments and suggestions most welcome!
      Regards,
      Arun
       
       
    • By kbrown
      Hi, 
      I've been working on a DIY fan for my 10" Skywatcher newt. My plan is to measure the ambient temperature and the mirror temperature with two separate thermistors and control the fan speed depending on the temperature difference. 
      My question is, does it make sense to use the fan if for some reason the ambient temperature is higher than the mirror? The fan is sucking the air out the tube at the moment. 


    • By Shardlowcol
      Hi, 
      I want to display FWHM values on a homemade focuser handset over USB from either BYN or Metaguide.
      Does anyone know if these programs even output their data, and can it be obtained?
      I have an arduino, and access to some good programmers thankfully.
       
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.