0
\$\begingroup\$

I got 23 meter of leds strip with 3 power supply which have a share ground to an Arduino. The Arduino can run perfectly the leds, I have shielded the cable from the arduino to the connector and I have no issues at this point.

When I connect my DSLR via HDMI (shielded cable ) and AC adaptor ( china made ), some leds start to flicker, and if I put the power cord closer, they flicker more.

I wonder if I just need to buy a better AC adaptor ( takes time ) or by sharing the DC ground of the camera, the flicker will go away ( I am afraid of damaging the camera and leds by doing that ).

One other solution that came up on my mind is to get a shielded sleeve to protect my leds from the power cord.

Any better idea?

\$\endgroup\$
1
\$\begingroup\$

My recommendation would be to put a large capacitor (>6800uF, perhaps) across the output of your AC-DC adapter. The flickering is due to the "ripple" which is left over after the rectification of the transformer output.

enter image description here

As seen in the image, the capacitor charges while the voltage of the rectified sine wave increases, and slowly discharges as the voltage decreases. The amount the capacitor discharges as the voltage decreases determines the amount of ripple (measured in volts). Increasing the capacitor size on the output reduces the output ripple. Just remember that the more current your circuit draws, the faster the capacitor will discharge during the voltage decrease, the larger the ripple will be, and the more your LEDs will flicker.

EDIT: After re-reading your question you say that the flicker gets worse as you bring your cord closer the flicker gets worse. This suggests that you're getting some interference from the mains. Shielded cable will help block electrostatic discharges and some electromagnetic interference, but not all of it. The EM field surrounding your power cord is inducing a fluctuating current in your DC circuit. Your best bet would be to keep the cord as far away from the setup as possible, as well as using a large capacitor on the output of your adapter (as mentioned before).

\$\endgroup\$
  • \$\begingroup\$ Thanks very helpful, unfortunately the space is very tight so even 40 cm away fro it, it helps only a bit... I got another power supply at 12V that is running across the LEDs which doesnt make any interference, maybe because it got this little block before the DC jack? ( I think is to remove any noise on the cable ) Also I can hear the noise from the transformer as soon as you apply some load, which makes me think is poorly made and this is why I get this issues. \$\endgroup\$ – max246 Mar 14 '16 at 19:49
  • \$\begingroup\$ I expect you're right that the adapter is poorly made. It likely has no shielding whatsoever and a very tiny filter capacitor (if any) on the output. Without pictures of your setup it is very difficult to understand what's going on, so I am just guessing here. I see the same thing happen all the time but for different reasons. \$\endgroup\$ – DerStrom8 Mar 14 '16 at 20:25
  • \$\begingroup\$ Do you think that a Ferrite Clip will help me out on absorbing the noise from the DC cable? I also have a smoke machine which when it got triggered via a Relay, the leds data absorbed the noise and flicker for like 1-2 seconds. This is very annoying, I am going to power the smoke machines via another power line and add a second Relay to trigger them. What I am left to improve on my setup is to get an official Panasonic adaptor but I might give a try with this Ferrite clip. \$\endgroup\$ – max246 Mar 16 '16 at 0:52
  • \$\begingroup\$ I wouldn't expect a ferrite clip to help much. Ferrite beads are used to filter out high frequency noise from power lines, but if you're seeing the LEDs flicker it means it's low frequency (50/60 Hz). \$\endgroup\$ – DerStrom8 Mar 16 '16 at 12:37
  • 1
    \$\begingroup\$ Good work on tracking down the cause! I would expect a simple isolation transformer would help, though I'm not sure it'll solve your problem completely. Only one way to find out! \$\endgroup\$ – DerStrom8 Mar 16 '16 at 20:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.