Wiring Diagram Remote Control

This circuit provides an FM modulated signal with an output power of around 500mW. The input Mic preamp is built around a couple of 2N3904 transistors, audio gain limited by the 5k preset. The oscillator is a colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF capacitors and the inductor. ( Click here for Colpitt Oscillator Resonant Frequency Equation.) Frequency is around 100Mhz with values shown.

4 Transistor Transmitter Circuit Diagram

Audio modulation is fed into the tank circuit via the 5p capacitor, the 10k resistor and 1N4002 controlling the amount of modulation. The oscillator output is fed into the 3.9uH inductor which will have a high impedance at RF frequencies.

The output stage operates as a class D amplifier, no direct bias is applied but the RF signal developed across the 3.9uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage.

All of the circuits on the PCB are configured so with the intention of as the photosensors are dark, the output of the 556 timers want stay peak. The issue delay period of each one 556 timer can be tainted by selecting as it should be combination ideals representing the R7/C2, R8/C3, R9/C4 and R10/C5 pairs.The LM339 input detection voltage levels for the circuit while publicized is settle on on 1/2 of the supply voltage. If a subordinate before elevated detection level voltage is wanted, the standards of resistors R5 and R6 can be there misused to suit.hint as soon as power is functional to the circuit, the outputs of the 556 timers pray be piercing in place of 1 discharge delay period phase. (Until the timing capacitors hold charged to 2/3rds of the supply voltage.) in attendance are RESET inputs for apiece LM556. 

These inputs complete not have terminal stop contacts but do have pads with holes to solder wires to if considered necessary. The RESET inputs might take place used to force the outputs of the 556 timers LOW until the timing capacitors have fully charged behind power is practical to the circuit but an outer timer would be required to accomplish this.This circuit does not require a regulated power supply and can carry on on supply voltages of up to 15 volts.

on behalf of in turn on other light detector circuits, comprehend Light Activated Detector Circuits by the side of this put.For added broad in a row on Voltage Comparators see the Voltage Comparator in sequence piece of paper by the side of this place.on behalf of further universal in sequence on LM556 timers see the 555 Timer Information bleep next to this place.threatening - If the polarity of the power supply for this circuit is reversed before the circuit is connected to an AC or else DCC source this circuit pray exist damaged. The most supply voltage meant for this circuit is 15 Volts.

A compact 2 transistor transmitter for use at VHF frequencies.

2 Transistor Transmitter Schematic Circuit Diagram

Notes:
Transistor T1 works as an audio preamplifier, gain is fixed at approximately R2/R1 or 100 times. The audio input is applied at the points LF in (on the diagram). P1 works as gain control. After amplification this audio signal now modulates the transmitter built around T2. Frequency is tunable using the trimmer CT and L1 is made using 3 turns of 1mm copper wire wound on a 5mm slug. The modulated signal passes via C6 to the antenna. A dipole can be made using 2 lengths of 65cm copper pipe. A DC power supply in the range 3 to 16 volts is required.