Hello everyone,

First off, I would like to say, "Great site". I've been searching the web the last few days and I'm glad to have found this one.

My apologies if my question is redundant. Please point me to other theads that have this covered.

I'm working on a project for my sons bicycle and would like your help.

I go on running towards the end of the day and sometimes it gets dark on us. He rides while I run. The bike currently had a 5 led flasher on the seat post but it's not bright enough. I want drivers to notice us.

After searching for a while, I've seen different setups using NE555 timer, 22uf 10v capacitor and resistors. These have resistors already installed on the strip.

I've purchased a 3 - 3528 led strip, but it doesn't provide specific information.

White
http://www.ebay.com/itm/2-x-White-3...117599?pt=US_Car_Lighting&hash=item19c91a2a5f

Red
http://www.ebay.com/itm/2-x-Red-352...845414?pt=US_Car_Lighting&hash=item1c2485fe26

White 12 led strip. On constantly, no flashing.
http://www.ebay.com/itm/24cm-Waterp...289820?pt=US_Car_Lighting&hash=item4d025f6c1c

At this time I have a 12v 7ah battery that will be mounted on the bike.

Here's what I'm looking for.

Flashing.
Two red led strips in the rear seat stay (rear fork).
Two white led strips in the front fork.

Constantly on.
One 12 led strip on the handle bars.

Could someone suggest the best method to complete this project? In the meantime, I'll continue researching.

If this setup is not bright enough, I will add a second pair of lights to the front and read. I'm currently waiting for the solderless breadboard to arrive. In the meantime, I would like to collect all components.

Thanks for you help,

Joe

 

Since those strips have built-in resistance for a 12V supply, all you need is a blinker circuit for the small strips of 3 on the front and rear. Try a 555 astable 50% duty cycle alternating left and right for both.

 

It is pretty straightforward, but I am not in a position to help right at the moment.

For the record, some members have brought up automotive restrictions. A bicycle does not fall under those, while a motorcycle does. This thread is OK.

 

Try a 555 astable 50% duty cycle alternating left and right for both.

+1 You could use a single "clock" to control all the blinking LEDs, so that would simplify the project. A 555 timer IC is one common way to make a clock. Another is to use a comparator (such as easy-to-find LM339) configured as a square wave generator. These are both popular and simple circuits that will give you control over the flashing frequency. Using a 556 dual timer would allow you to use the extra timer to cycle the flashing frequency from slow to fast and back to slow. This can make the flashing even more attention-grabbing.

 

Thanks for the input guys. Which other components do you recommend I use along with the ones provided?

Thanks again...

 

For the timing components, I would use a 1μF or 2.2μF ceramic (MLCC) capacitor with high value resistors to avoid the aging problems associated with electrolytic capacitors.

 

You may need a small (low current rating) MOSFET to act as your power switch. It will take the output of your clock directly and complete the path to ground when the clock goes high, and then shut it off when the clock is low. A 555-based clock can drive enough current on it's own that you might not need this extra component. But you'll have to calculate it out and be sure you stay well below the rating. Personally, I'd use the MOSFET either way since it's a simple way to remove concern about the current level of the load being switched. Just choose an n-channel MOSFET with a continuos current rating >4X over your expected load. For LEDs, this means just about any MOSFET will be enough.

 

Hi guys,

I'm having a tough time figuring the best method to make flashing/strobe led circuit. Could someone help me designing a circuit? Which components to use?

Maybe point me to a resource online that can help?

I'm new to this and not making much progress. I have a couple books.coming in from the library. Hope to have them in next week.

Thanks.

 

No problem. What are the odds you will do other electronic projects? If there is a slight chance it would be worth buying a protoboard, otherwise not.

Here is a starting concept, it can be tweak or changed for something better later.

555 Hysteretic Oscillator

Bill's Index

 

Thanks for the information. At this time I have a small solderless breadboard. Once working on it I'll post our progress.

 

If you want to change the pulse durations, the on/off times, let me know. I have some other circuits you might be interested in, part of a series. Some of them include really long duration flashers, but not too applicable for a LED strip.

 

This may resemble what Bill offers but I thought I would share it anyway - it's something I made recently that works well.

It uses the output of a slow-running (0.1Hz? I forget) 555 timer applied to the control pin of second timer running at about 0.7Hz. The slow moving voltage on the control pin of the second timer causes it to cycle from 0.4Hz up to 1Hz. I've worked out all the math of this into a spreadsheet, if anyone wants to play around with it. I guess the simulation programs should handle it too.

 

Thanks for the information.

The pattern I was looking for is similar to police. Instead of blue and red, it'll be white and red. White in front, red out back. It doesn't need to be exactly as police flashing. But something that can get drivers attention. Something that will flash quick, similar to strobe.

Thanks again.

 

I have designed many police flashers for RC cars, modifying them for a bike would be easy, as long as the color scheme is kept legal.

Here is a typical description.

Side1 <flash><flash><flash>
Side2 <flash><flash><flash>

Of course, circuit complexity goes up a little. What are you wanting?

If you want a long duration flasher, which could be handy as a backup, look through some of my other articles.

Bill's Index

LEDs, 555s, Flashers, and Light Chasers

The 555 Projects
This one has several projects that flashed an LED or two quite brightly for several weeks continuous off two AAA batteries, my goal was a month. Bigger batteries will last longer.

 

The pattern you described is what I was looking for.

Here is a typical description.

Side1 <flash><flash><flash>
Side2 <flash><flash><flash>

The most it would be used is about one hour at a time, 3 to 5 times a week. If it gets dark on us. Which batteries to you suggest? I do have a 12v7ah that I could put on a rack or somewhere on the frame.