Intro: Wireless Motorcycle/bicycle Helmet Brake Light ..very Easy
the main idea of this project is when i hit the motorcycle brake lever the led lights on the helmet or jacket light up making the rider more visible and hence safer on the streets.I didnt want the wires all dangling from the bike to the helmet so i made a wireless module.
Step 1: Things Required
>battery(i used a lithium ion 3.7V battery
>433 mhz rx
>433 mhz tx
Step 2: Tranmitter Part
connect the circuit as shown above.
we are making use of 433mhz rf module for the wireless communication.first assemble the circuit on a breadboard make sure everything works fine and then proceed to soldering. The transmitter of the 433 mhz module will have 4 pins as shown in the figure. namely ground , data , vcc, antenna.since we are using it on a motorcycle take the wire out from the motorcycle which goes to the rear brake light and attach it to the input side of the ic 7805 we are going to use the output of the ic as both a power source as well as a data signal, therefore connect the output of ic7805 to both vcc and data pin on 433 mhz Tx. Now ground both the the ic7805 and rf module .the antenna can be made of a wire 17.3 cm long.
The tranmitter part is done
Step 3: Reciever Part
The reciever part has four components
>the rf Rx module
>the opamp ic 741
we use the 433 MHz Rx to recieve the transmitted signal .When a logic 1 is transmitted we recieve a logic 1 but when we send logic 0 we expect a logic 0 but that is not the case we get some voltage around 2 volts therefore we use a opmap ic as comparator and clamp down the recieved logic zero voltage to 0V. now the output of the opamp ic is does not provide enough current to drive the relay therefore we use a transistor acting like a switch. When the base current is zero the transistor acts like a open switch and does not let current ic to flow.When the base current is provided the transistor acts like a closed switch and provides a path for current ic to flow. The base of the transistor is connected to the output of the opamp circuit .the emitter is grounded and the collector is connected to the relay as a load. The relay acts as a switching network to drive bigger lamps or lights as per your wish.
Step 4: Test Your Circuit and Have Fun.
attach leds on the helmet or attach them on the jacket as per your liking. be safe on the road .cheers.
disclaimer- make sure its legal in your country to put up such lights .