Hello

I am a gcse student in England working on a road safety electronics project. I plan to build a light which mounts onto a bike meaning the rider can be easily seen. To do this I must build a circuit which is what my problem is. Due to my basic knowledge of electronics and components I need you help. I would like to build a light that can flash but also stay on constantly. I believe I can do this by using a 555ic but I'm not sure. The circuit needs to be quite complex to achieve a good grade. Any help or advice would be appreciated.

Thanks

 

Need much more info. How bright the light? Just one flash rate? What or who decides steady on or flash?

Length of operation? And any other details you can think of. One detail can change everything.

 

Need much more info. How bright the light? Just one flash rate? What or who decides steady on or flash?

Length of operation? And any other details you can think of. One detail can change everything.

Erm currently I think I want to use a multi 'mode' button to control when it flashes and when it is constant. I don't know how bright the lights will be but I am using 4 white LEDs . It only needs one flash rate and that can be of any speed. When I get more work done on the specifications I'll let you know. Thanks for the fast reply

 

You may benefit from this blog:
https://forum.allaboutcircuits.com/threads/leds-555s-flashers-and-light-chasers.19075/

The circuit needs to be quite complex to achieve a good grade.

Surely a simple circuit is preferred over a complex one? Do you really think you'll get a better grade by adding unnecessary complexity?

 

You may want to consider using a LED equivalent of the old automotive 1157 dual filament lamp. The 1157 lamp typically served as a tail light with a filament also for turn signal or brake which was the brighter of the two. There are LED replacements for this bulb available. The LED replacements can be extremely bright making for high visibility which is what you want on a bicycle, especially during hours of darkness.

While a 555 timer is a good choice it is limited in what it can directly source or sink for current output. You will likely need a transistor or a MOSFET to adequately drive the lamps.

Personally I wouldn't use a 555. I would consider using a micro-controller for a project like this, simply because it offers more options. The UK is home to the basic and simple PICAXE chips. A simple little 8 pin chip (same as a 555 pin count) has endless possibilities for a project like this and programming something at this level is not difficult. Literally thousands of code samples out there online to copy and paste. A simple PICAXE 08M2 cost under $3.00 USD. They also have a pretty good PICAXE Forum loaded with help.

The merit of using a small simple micro-controller is you tell it what you want it to do. For example have a low intensity lamp always on and flash the brighter intensity at some rate. You want to get cool about it rig a switch to the brake so the bike has a brake light which flashes calling attention to a stopping rider. The possibilities end with your imagination. Bicyclist around me all use those everyday boring LEDs which blink and they can be store bought for a few USD, literally. You can only do so much as to getting creative with bicycle lighting so I suggest you get real creative because making a light blink is not quite what gets high grades or reflects creativity.

Ron

 

You may want to consider using a LED equivalent of the old automotive 1157 dual filament lamp. The 1157 lamp typically served as a tail light with a filament also for turn signal or brake which was the brighter of the two. There are LED replacements for this bulb available. The LED replacements can be extremely bright making for high visibility which is what you want on a bicycle, especially during hours of darkness.

While a 555 timer is a good choice it is limited in what it can directly source or sink for current output. You will likely need a transistor or a MOSFET to adequately drive the lamps.

Personally I wouldn't use a 555. I would consider using a micro-controller for a project like this, simply because it offers more options. The UK is home to the basic and simple PICAXE chips. A simple little 8 pin chip (same as a 555 pin count) has endless possibilities for a project like this and programming something at this level is not difficult. Literally thousands of code samples out there online to copy and paste. A simple PICAXE 08M2 cost under $3.00 USD. They also have a pretty good PICAXE Forum loaded with help.

The merit of using a small simple micro-controller is you tell it what you want it to do. For example have a low intensity lamp always on and flash the brighter intensity at some rate. You want to get cool about it rig a switch to the brake so the bike has a brake light which flashes calling attention to a stopping rider. The possibilities end with your imagination. Bicyclist around me all use those everyday boring LEDs which blink and they can be store bought for a few USD, literally. You can only do so much as to getting creative with bicycle lighting so I suggest you get real creative because making a light blink is not quite what gets high grades or reflects creativity.

Ron

Thank you very much for your advice. My teacher thinks using a micro controller is a good idea so I'll have a think about what I want to do.

Cheers

 

Hope it works out well for you.

Ron