Author Topic: Making a rear light a "blinky"?  (Read 916 times)


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Making a rear light a "blinky"?
« on: January 07, 2017, 10:36:05 PM »
As I wait for my dynamo hubs and lights I find I have time to think! Wondering if it is possible to have a rear dynamo powered light be able to function in a blinking mode?


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Re: Making a rear light a "blinky"?
« Reply #1 on: January 07, 2017, 11:02:21 PM »
Well, sure!

I have done this in the past with success.

So long as the working voltage of the blinky is within range of the dynamo's output (or throttled down using resistors), there is no reason why a rectified (AC to DC) dynamo-supplied current can't power a blinky. This is what I did and it worked fine. However, I switched away from this, because I valued having a standlight and separate blinky more.

It would have been possible to install a voltage sensor to switch the LED blinky from DC dynamo current to battery, but I simply attached a second blinky for standlight duties and then I realized -- despite all my work -- I could simply have attached a blinky alongside my dynamo-powered tailight with standlight to begin with, so that's what I've done ever since.

All the best,

« Last Edit: January 07, 2017, 11:20:40 PM by Danneaux »

Andre Jute

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Re: Making a rear light a "blinky"?
« Reply #2 on: January 07, 2017, 11:47:58 PM »
Wondering if it is possible to have a rear dynamo powered light be able to function in a blinking mode?

Don't see why not. You could DIY the entire lamp with a 555 timer, a few fixed resistors, a variable resistor (a potentiometer, to vary the blinking speed) and a small cap, plus enough red LEDs to make up the correct voltage in a series-parallel arrangement. Here's a very simple way of doing it (this fellow is making blinking turn signals but the principle is the same).

Here's another guy with a good practical demo of a variable blinking speed board.

In each case your dynohub stands in for the battery.

But you can probably buy a good German battery blinky (they do sell them, as they're legal for road bikes in Germany) for less than the cost of the components to DIY it, and just run it beside your standard lamp or attached to your jacket or helmet.

Personally, I would just buy a red blinky battery torch from China because it already has the circuit built in and above all has a waterproof case, fit it near my BUMM Toplight Line Plus to a seat stay or the rack with a fishmouth, and arrange to deliver dynohub power to it. I use such a small torch, powered by a 3.7V 18650 battery, as a front white blinky next to a BUMM CYO and it is eminently satisfactory. It's just too much hassle and wiring to deliver dyno power to it.


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Re: Making a rear light a "blinky"?
« Reply #3 on: January 08, 2017, 04:21:28 PM »
Do you think that you might want to use the taillight while you are also using a USB charger?  I use battery power taillight because I want to be able to use my USB charger while I am also using a taillight during daytime (in blink mode).  My headlamps have the output for the taillight wiring, but the taillights are only energized when the headlamp is on, which negates USB charging.

And one more reason that I use battery for taillights that probably is unique to me, I have S&S couplers and I did not want to deal with taillight wiring when I pack up the bike.

I do not know if you are setting it up for USB charging or not, so I just thought I would mention it.