Power supply: 12-14 V stab., 100 mA. RF power: 400 mW. Impedance: 50-75 ohm. Frequency range: 87,5-108 MHz. Modulation: wideband FM. Connect the 6 V / 0,1 A bulb to the output and use R1 to tune the right frequency. Maybe you might stretch coils of the L1. Then use C14 and C15 to adjust the highest power (the highest light of the bulb). Then you can connect antenna and audio signal. Adjust R2 until the audio sounds as loud as the other stations. With good antenna (dipole placed outdoor and high) the transmitter has very good coverage range about 500 meters, the maximal coverage range is up to 4 km.
Click here to download the full size of the above Circuit.
C1, C2, C12 - 100 pF (ceramic)
C3, C5 - 0,22 uF (electrolytic)
C4 - 1,8 nF (plastic)
C13, C16, C17, C19 - 1 nF (ceramic)
C8, C9 - 10 pF (ceramic)
C10 - 47 pF (ceramic)
C11 - 8,2 pF (ceramic)
C14 - 60 pF trimmer
C15 - 35 pF trimmer
C18, C7 - 100 nF (ceramic)
C20 - 470 uF (electrolytic, 16 V)
(All coils are free-standing air-core types, wound of 0,7 mm Cu wire, 6 mm internal diameter.)
L1 - 4,5 coils
L2 - 9,5 coils
L3 - 4,5 coils
R1, R2 - 10 k pot.
R3 - 33 k
R4, R7, R12 - 10 k
R5, R11 - 470
R6 - 27 k
R8 - 22 k
R9 - 270
R10 - 100
D1 - BB409 (BB109G, BBY31) varicap
T1 - BC547C (BC548C, BC547B)
T2 - BFR91A (BFR96)
T3 - BFR96
3,5 mm jack
CD player, computer
6 V / 0,1 A bulb
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.....