This intercom box takes input from any 2-way radio (FRS, GMRS, etc), cell phone, and a stereo audio source and amplifies them for listening via a headset in your helmet. The headset is a modified Chatterbox stereo headset. The standard Chatterbox mic is removed and replaced with a noise-cancelling mic with a high density windsock.
Click here to download the full size of the above Circuit.
This should provide good wind noise rejection and a convenient mount for the mic in a full face helmet. The audio isolation transformer (L1) eliminates echo resulting from the fact that the FRS radio doesn`t share the same ground for both audio and mic. Since the cell phone does share a ground, the transformer is unnecessary. If you wish to power this box and your other devices off of bike power, have a look at Bill Bowden`s Hobby Circuits, particullarly the Variable Voltage Regulator. This curcuit will alow you to transform bike power into a clean voltage source for your FRS, CD, amplifier, etc. Cut the mic off the Chatterbox headset and solder on the WM55 mic. Insert the WM55 into the windsock and zip-tie the opening closed. Now the mic can be velcroed onto the helmet chin bar. Mount the headphone speakers and carefully tuck in all of the wires. You want to leave the plug where it`s not in the way, but easily accessable to attach the cord. Well, take the parts you`ve collected and follow the diagram below. The output of the amp and the input from the mic are connected to the hatterbox headset via a 6-pin mini din connector. Although it is not noted, I speced a 3. 5mm stereo jack for the "To FRS Audio Out" in hopes of getting a radio with the shared ground type headset plug like a cell phone. It may be necessary to use two mono jacks, one for the FRS audio and one for the FRS mic. Either way, we ought to be able to make...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: