Capacitor application

Thread Starter

acieus

Joined May 24, 2020
3
Hey folks,
New to the forum here and have a question I'm hoping someone can answer. I have a couple of LED turn signals that I bought, these babies are a strip of LEDs that roll from one side to the other which looks pretty wicked on my motorcycle. Only thing is the flasher cuts the power to the strips a bit too early which throws their sequence off every third or so flash. I was thinking of installing a capacitor in series with the source power to extend the length of time power was applied to the strips to correct this.

Firstly, would this be an incorrect approach to this, given that the capacitor may interrupt the power during charge-up and negate the effect I'm looking for?

Secondly, if the answer to the first question is "no", what formula would I need to use to determine what size of capacitor I would need to extend the power being provided to the LED strip?

Any guidance appreciated here.

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ElectricSpidey

Joined Dec 2, 2017
1,144
The cap would go in parallel with the LED strip, but might have to be pretty large depending on the current requirements of the strip.

Does your LED strip have a "control" line, or just "power" leads?

You might want to think about a simple timer control in between the flasher output and the LED strip.
 
Last edited:

dl324

Joined Mar 30, 2015
10,736
Welcome to AAC!
these babies are a strip of LEDs that roll from one side to the other which looks pretty wicked on my motorcycle.
Is this modification legal in your region? In my country, color, brightness, and flash rate are parameters that must be approved.
 

Thread Starter

acieus

Joined May 24, 2020
3
The cap would go in parallel with the LED strip, but might have to be pretty large depending on the current requirements of the strip.

Does your LED strip have a "control" line, or just "power" leads?

You might want to think about a simple timer control in between the flasher output and the LED strip.
The strip has power leads only. It would just need to be extended for a few microseconds.
 

Wolframore

Joined Jan 21, 2019
1,748
simple, get rid of the flasher and put in a relay, assuming nothing else needs flashing... or separate the light strips to a standard relay circuit from the turn signal light switch. Bypass the flasher.
 

Tonyr1084

Joined Sep 24, 2015
4,521
I'm assuming that when you power these LED strips they automatically scan from one end to the other repeatedly, over and over until power is cut. Since blinkers don't provide continuous power - you'll need to supply your own source of power; either from the bike battery or from some other source. Then, when the blinkers are activated they can then activate a circuit that will stay on for a small period of time after the blinkers stop blinking. Meaning blink power comes on, goes off, comes on, off, on, off - so on and so on. The circuit will need to come on when the blinkers come on but continue to hold power on for (just guessing, I've never timed blinkers before) power needs to hold for about one second. With each flash of the blinker you reset the circuit, keeping the LED strips activated. When the last blink ends, one second after that the LED strips shut off.

Otherwise, a bank of capacitors would be quite large because it's likely the LED strips take more current than a simple capacitor can deliver. Here's a video I did some years back in response to a question about lighting an LED and having it dim out. Two things to keep in mind - first, the LED I light is a single LED with a resistor to prevent over current, which will burn out the LED. The second thing to keep in mind is that this is ONLY an LED and resistor. The circuitry in your LED strip will also consume power. That's why a very large cap or bank of capacitors will be necessary. And what comes with high capacitance comes high charge current and longer charge time.

 

Thread Starter

acieus

Joined May 24, 2020
3
Sounds about right. The only reason I wouldn't want to deliver consistent switched current to these things is to try and keep them in synch with the tail light signals. Hence trying to extend the current supplied to the strips for a brief period. Hope that makes sense.
 

ElectricSpidey

Joined Dec 2, 2017
1,144
Using a cap here could present some problems.
1. The flasher circuit might not like the surge current caused by the cap.
2. the LED strip might not like the power drop-off as the cap discharges.
Just be aware...
 
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