Courtesy Light Extender

In essence, this circuit is a 15 to 20-second courtesy light extender for cars. It is activated in the usual way by opening a door but it also samples the negative lock/unlock signals from a car alarm or central locking and does two more things. First, when an unlock signal is received, it turns on the courtesy light for 15-20 seconds before you open the door. Second, when a lock signal is received, it turns off the courtesy light immediately, with no fade-out. This is done to eliminate false triggering of the burglar alarm through current drain sensing. When a car door is open or the unlock relay is activated, the 33µF capacitor discharges through diode D1 and this keeps transistor Q1 turned off.

Circuit diagram:

Courtesy Light Extender Circuit Diagram

This allows Q2 and Q3 to turn on and the courtesy lamp is activated. When the door is closed, the courtesy lamps stay illuminated and the 33µF electrolytic capacitor starts charging through the associated 1MO resistor. As the voltages rises, Q1 turns on slowly, turning off Q2 and Q3 which gradually fades out the courtesy lamp. If a lock signal from the central locking system is received, relay 1 closes and charges the capacitor instantly, so the lamp turns off immediately. Relays were used to interface to the central locking/alarm system as a safety feature, to provide isolation in case something goes wrong.

Author: Matt Downey - Copyright: Silicon Chip Electronics

Comments

PID instruction in Allen Bradley PLC Closed Loop Control

PID instruction in Allen Bradley PLC [Proportional/Integral/Derivative] Closed Loop Control For Processor SLC 5/02SLC 5/03SLC 5/04SLC 5/05 MicroLogix 1200 and MicroLogix 1500 (A special PID file replaces the old integer file control block.) Description of PID in PLC This output instruction is used to control physical properties such as temperature, pressure, liquid level, or flow rate of process loops. The PID instruction normally controls a closed loop using inputs from an analog input module and providing an output to an analog output module as a response to effectively hold a process variable at a desired set point. The PID equation controls the process by sending an output signal to the actuator. The greater the error between the setpoint and the process variable input, the greater the output signal, and vice versa. An additional value (feed forward or bias) can be added to the control output as an offset. The result of the PID calculation (control vari...

NE566 Function Generator Circuit Diagram

The NE566 Function Generator is a Voltage-Controlled Oscillator of exceptional linearity with buf fered square wave and triangle wave outputs. The frequency of oscillation is determined by an external resistor and capacitor and the voltage applied to the control terminal. The Oscillator CAN be programmed over a ten-to-one frequency range by proper selection of an external resistance and modulated over a ten-to-one range by the control voltage, with exceptional linearity. FMAX = 1 MHz WIDE 1000:1 Continuous Sweep Possible NE566 Function Generator Circuit Diagram Pdf Datasheet Sourced by : Circuitsstream

Long Loopstick Antenna Circuit Diagram

Circuit Diagram Description Wound on a 3 foot length of PVC pipe, the long loopstick antenna was an experiment to try to improve AM radio reception without using a long wire or ground. It works fairly well and greatly improved reception of a weak station 130 miles away. A longer rod antenna will probably work better if space allows. The number of turns of wire needed for the loopstick can be worked out from the single layer, air core inductance formula: Inductance = (radius^2 * turns^2) / ((9*radius)+(10*length)) where dimensions are in inches and inductance is in microhenrys. The inductance should be about 230 microhenrys to operate with a standard AM radio tuning capacitor (33-330 pF). The 3 foot PVC pipe is wound with approximately 500 evenly spaced turns of #24 copper wire which forms an inductor of about 170 microhenrys, but I ended up with a little more (213uH) because the winding spacing wasn't exactly even. A secondary coil of about 50 turns is wound along the length of th...

Mutchus

Search This Blog