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Cycle Indicator Lights


New Member
I have tried to solve the problem of cycle indicator lights, and made a flasher circuit using a 555 timer, 7.4 volts from two Li-ion batteries, and BA15S 5050 160 lumen LED bulbs. The problem is that the light is not bright enough for motorists to notice in sunlight.

I have a feeling that I should be using a much more powerful LED and make it flash for micro-seconds by charging a large capacitor (possibly with a voltage pump) and then discharging it to the LED every half second, on the assumption that the overall energy used will be similar but the visibility will be far better.

Can anyone say if this is a correct assumption, and if there is a standard solution to get a very bright short flash from an LED?

With thanks for any response.


Well-Known Member
Most Helpful Member
It won't make much difference. A very brief flash may be more visible but it won't be recognised as a indicator, partly because indicators spend equal times on and off.

I've got a 1953 car, with trafficators, the little arms that stick out and light up yellow, to do what indicators do. By about 1980, they had stopped working. They still stuck out and lit up in response to the control, but to work, the person who sees them has to understand what they mean. That understanding isn't there, and my car, and just about every one of the same model that's got a photo on the internet, has a set of orange flashing indicators, as the owners want to drive them and have indicators that work, all the way through the electrics, the light, and into the place it matters, the brain of the person who sees them.

When I went to America, it took me time to learn that a red flashing light on the rear of a vehicle meant the same as an orange flashing light. The simple fact is easy to learn. If you didn't know it before you read this post, you do now. It's the acquired skill that the red flashing light means that the vehicle is going to turn, that bypasses conscious thought and means that drivers in the USA just know that the car will turn, the same way everyone knows what non-flashing bright red lights mean on the back of car.

I've seen yellow direction indicators in use on bikes on two occasions, separated by about 40 years. I bike a lot. I did 16 miles this morning. However, I am never going to learn that yellow flashing lights mean that the cyclist intends to turn, as I doubt that I will ever see another bike with yellow direction indicators. If I do see one, I will have to actually think about it, and make a conscious decision, and that will always be far slower than my instantaneous understanding what it means when the cyclist sticks his or her arm out to one side.


Well-Known Member
Most Helpful Member
A bright short flash from an LED will probably burn it out soon.
A blink duration less than 30ms appears to be dimmed.
Use an xenon bulb for very bright short flashes because they are much brighter than a blinking LED.

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