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DIY DashCam: Power challenges

I have a long-time friend and colleague, Bob Diamond, Department Head, Mechanical Engineering at L3 Narda-MITEQ on Long Island, NY. We worked together in the 80s at General Microwave Corp. in NY—Bob was a mechanical engineer and I was an analog and power engineer there at that time. We’ve both come a long way in 35 years.

Here is Bob’s brief description of his recent addition to his car with a dashcam and some subsequent problems he encountered with noise on his AM Radio:

My daily commute is about 12 miles each way from Babylon to Hauppague and back. The best North-South route for me is using the Sagtikos Parkway most of the way. The Sagtikos Parkway goes North and South in an almost perfect straight line for over 10 miles. Many drivers on this road think they can go near 90 MPH until they end up crashing into the car in front or alongside them. It is one of the most accident-prone routes on Long Island.

In my near 20 years of driving this road I have never had an accident but I‘ve had a few close calls and have seen an un-countable number of accidents. Because of this, I thought it would be a good idea to install a dashcam on my car; God forbid I get caught up in an accident or a witness to one. Plus, I enjoy doing ‘mods’ to my car and playing with electronic toys! (Editor Steve T: “I love when ‘Mechanical guys’ do electronics/electrical DIY projects! Bob is a very versatile engineer; you can be sure I will be calling on him when I run into any mechanical challenges in my projects. )

Because of the above, I bought a mid-dollar range dashcam and mounted it on my windshield. The power supply for the dashcam has a mini USB plug at the dash cam end and a power plug (cigarette lighter plug) at the other end. I didn’t like the wire hanging down from the cam, across my dashboard and into the power receptacle. When I do mods to a car, I want it to look factory installed.

After some internet research, I found a company called ‘The DashCam Store’ that sells hard-wired power supplies for Dashcams. You run the wire from the Dashcam up and under the headliner, down and under the pillar trim, and then down into the fuse panel. The kit includes a DC-DC converter (see Figure 1) that you plug into the fuse panel and chassis ground. This all becomes hidden inside the fuse panel area.

Figure 1

The power supply that came with the DashCam

The power supply that came with the DashCam

Even though I have a great sound system in my car, plus satellite radio, I still listen to AM radio quite often for news, traffic and weather. I normally listen to WCBS AM, which is 880 on the AM dial. WCBS is a 50,000 Watt clear-channel broadcast station. As soon as I installed the Dashcam kit, all of my AM reception was wiped out by interference from the Dashcam DC-DC converter. I tried a direct ground to the battery, shielding the DC-DC converter in a metal box and a Mu-Metal box with no improvement. I also tried re-routing the wires and shielding the wires, also with no improvement. At that point I contacted Steve Taranovich, knowing that ‘Mr. Analog’ would most likely know of a solution.

He was kind enough to direct me to Linear Technology and they supplied me with their LT8645S Step-Down Silent Switcher test board as Steve recommended.

I bought a plastic electronics project box and mounted the board in the box (see Figure 2).

Figure 2

The Linear Technology LT8645S demo board which solved the noise problem.

The Linear Technology LT8645S demo board which solved the noise problem.

Then I simply cut the input and output wires off the DashCam Store DC-DC converter and soldered them to the LT8645S board. Before I closed everything up I started the car, turned on WCBS 880 AM and Voila!— ZERO interference, crystal clear AM reception. I scanned up and down the entire AM band and all is crystal clear. It works perfectly!

Editor Steve T: I love a story with a happy ending. See my review of this Linear Tech power solution on EDN, Silence is golden: 65V, 8A synchronous step-down switching regulator.

7 comments on “DIY DashCam: Power challenges

  1. SebastienA
    July 5, 2017

    Thanks for the story Steve and the reference to the synchronous convertor eval kit.  A great extension to this article would be a tear-down and analysis of the offending convertor to see what they did wrong to cause such high conducted and radiated emissions.

  2. David Ashton
    July 5, 2017

    Max the Magnificent did a recent story on Dashcams and (I think, I can't find it) mentioned the Dashcam Store, who otherwise seem to be a highly professional outfit.  Have you tried contacting them about this?  The seemed the kind of outfit that would find a solution for you (not that you need one now, but you'd be doing other customers a service if this problem was sorted out)

  3. Steve Taranovich
    July 5, 2017

    Hi David—Excellent point—I have been thinking of contacting them and now you have urged me, so I will definitely want to hear their side of the story

  4. Max the Magnificent
    July 6, 2017

    Hi Steve — Max here — the article to which David refers was Shoot! What's the Dash Cam Say? ( eetimes.com/author.asp?section_id=216&doc_id=1331491 )

    Katie from the DashCamStore offered some very useful advice in the comments to this article, including pointing me at this buyers guide ( thedashcamstore.com/buyers-guide/ )

    As David said, my impression is that the folks at the DashCamStore are eager to help.

  5. Steve Taranovich
    July 6, 2017

    Hi Max—thanks for that added information for our audience—I read that EETimes article—-nice!

    I think that, being a 'geek' circuit designer like you, I jumped at the chance to help solve a problem, especially since I had recently written a Product review on EDN of the power solution I gave to Bob.

    I am happy that our audience can now fully understand what the DashCamStore has to offer to its customers in the way of products and service.

  6. HughVartanian
    July 11, 2017

    I had an issue with my dashcam lighter-plug power supply however in my case it interfered with the FM reception, particularly for somewhat distant stations.  I grabbed a no-longer-in-service phone charger plug, cut the phone plug off and spliced it to the dashcam power cord.  Worked fine.  Found a use for an old charger too!

    -Hugh

  7. Steve Taranovich
    July 12, 2017

    @HughVartanian—Nice use of a piece of electronics gear no longer used! I have boxes full of things like that as I am sure many of our readers do as well.

     

    This might be a good blog topic for Planet Analog!

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