Flash Lights with HT2014L

This scheme is almost the same with a flash light with LM3909. In this scheme only requires IC HT2014L as a leader, and a resistor and LED. For voltage here need ration power around 4.5 V. You can apply this series to a wider scale in comparing the use IC LM3909. For the scheme are below:

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Police Lights Circuit with 555 and 4017 IC

This circuit uses a 555 timer which is setup to both runn in an Astable operating mode. This generates a continuous output via Pin 3 in the form of a square wave. When the timers output changes to a high state this triggers the a cycle on the 4017 4017 decade counter telling it to output the next sequential output high. The outputs of the 4017 are connected to the LEDs turning them on and off.

Police Lights Circuit Schematic

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Automatic Room lock and Lights circuit Wiring diagram

This schema counts and indicates up to nine persons present in the room and automatically locks the door and switches off lights as soon as they leave. It automatically switches on the lights when the first person enters the room. The schema can be used as a power-saving device and a security device to prevent unauthorised entry in the room, especially in a business meeting room.

Circuit and working

The schema, shown in Fig. 1, is built around three NE555 timer ICs (IC1, IC2 and IC6), an up/down BCD decade counter 74LS192 (IC3), a 7-segment display driver 74LS47 (IC4), 4-input NOR gate HEF4002B (IC5) and a common-anode 7-segment display LTS542 (DIS1). S1 and S2 are foot switches. S1 is installed under door-mat of the door used to enter the room, and S2 is installed under a door-mat just inside the room.

The outputs of IC3 change state synchronously with the low-to-high transitions on the clock inputs. Separate count up (CPU) and count down (CPD) pins of IC3 are used here. Its parallel pin 11 is made high and parallel data input pins 15, 1, 10 and 9, along with master reset pin 14, are made low in this schema.

The outputs (Q0 through Q3) of IC3 are given to IC4 to drive display DIS1. Resistor R11 is used to limit the current flowing through DIS1.

Outputs of IC3 are also given to IC5. output O1 of IC5 is fed to relay-driver transistor T3 through resistor R9 to energise relay RL1. Light switches off when RL1 is energised. The second output O2 is fed to relay-driver transistor T4 to energise relay RL2 for locking the door. RL1 and RL2 energise simultaneously as inputs of 4-input NOR gate (IC5) are connected to both the drivers.

Fig. 1: schema diagram of the automatic lock and lights schema

Fig. 2: An actual-size, single-side PCB for the automatic room-lock and lights schema

Fig. 3: Component layout for the PCB

Output O2 of IC5 is also given to the base of transistor T7 whose collector is connected to the base of transistor T6. When O2 of IC5 goes high, it locks the door and makes the Vcc pin 8 of IC1 low to stop further counting.

To open the lock, press switches S3 and S4 (acting as security keys) simultaneously. The mononstable schema built around NE555 (IC6) triggers and its output goes high for around 11 seconds and makes the base of transistor T4 low, via transistor T5. This action de-enegises relay RL2 to open the lock for a pre-defined time period based on the values of R12 and C5. At least one person should enter the room within this time period, otherwise it will get locked again. During this period, Vcc pin 8 remains high to enable IC1.

When each person enters the room and presses foot switch S1, counter IC3 advances by one count and display shows the number of persons in the room. On first person’s entry, the outputs O1 and O2 of IC5 go low, transistors T3 and T4 stop conducting and relays RL1 and RL2 de-energise to switch on the light and open the door lock.

Similarly, when they start leaving the room by enabling foot switch S2, counter IC3 reduces by one count and the display shows the number of persons present in the room. the outputs O1 and O2 of IC5 remain low, so light remains on and door remains open till the room is vacant.

Construction and testing

An actual-size, single-side PCB for the schema is shown in Fig. 2 and its component layout in Fig. 3. After assembling the schema on PCB, enclose it in a suitable case. Switches S1 and S2 should be installed as explained earlier. The display can be installed on the door frame outside the room. Fix switches S3 and S4 at a suitable location such that you can press them simultaneously when needed.

Connect the door-lock assembly to relay RL2 contacts using external wires as shown in Fig. 1. Use a 2-pin connector each for connecting the light and lock assembly.

EFY note. Avoid entry of more than nine persons. Otherwise, at the entry of 10th person, the display will show ‘0,’ the door will get locked and the lights will switch off. If this happens, someone will have to press switch S2 from inside the room to open the lock and switch on the lights.

Sourced by: EFY : Author Name:  Suresh Dwivedi

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Lights Control for Model Cars Wiring diagram Schematic

The author gave his partner a radio controlled (RC) model car as a gif t. She found it a lot of fun, but thought that adding realistic lights would be a definite improvement. So the author went back to his shed, plugged in his soldering iron, and set to work equipping the car with realistic indicators, headlights, tail lights and brake lights.

Lights Control for Model Cars Circuit Diagram

The basic idea was to tap into the signal from the radio control receiver and, with a bit of help from a microcontroller, simulate indicators using flashing yellow LEDs and brake lights using red LEDs. Further red LEDs are used for the tail lights, and white LEDs for the headlights. Connectors JP4 and JP5 (channel 0) are wired in parallel, as are JP6 and JP7 (channel 1), allowing the schema to be inserted into the servo control cables for the steering and drive motor respectively. The ATtiny45 micro-controller takes power from the radio receiver via diode D1. T1 and T2 buffer the servo signals to protect IC1’s inputs from damage. 

IC1 analyses the PWM servo signals and gen-erates suitable outputs to switch the LEDs via the driver transistors. T3 drives the two left indicators (yellow), T4 the two right indica-tors, and T5 the brake LEDs (red). The red tail lights (JP2-8 and JP2-8) and the white head-lights (JP2-9 and JP2-10) are lit continuously. The brake lights are driven with a full 20 mA, so that they are noticeably brighter than the tail lights, which only receive 5 mA. If you wish to combine the functions of tail light and brake light, saving t wo red LEDs, sim-ply connect pin 10 of JP2 to pin 14 and pin 12 to pin 16. Then connect the two combined brake/tail LEDs either at JP2-5 and JP2-6 or at JP2-7 and JP2-8.

JP3 is provided to allow the use of a separate lighting supply. This can either be connected to an additional four-cell battery pack or to the main supply for the drive motor. The val-ues given for resistors R8 to R17 are suitable for use with a 4.8 V supply. JP2 can take the form of a 2x10 header.

As usual the sof t ware is available as a free download from the Elektor web pages accom-panying this article[1], and ready-programmed microcontrollers are also available. The microcontroller must be taught what servo signals correspond to left and right turns, and to full throttle and full braking. First connect the fin-ished schema to the radio control electronics in the car, making sure everything is switched of f. Fit jumper JP1 to enable configuration mode, switch on the radio control transmit-ter, set all proportional controls to their cen-tre positions, and then switch on the receiver. The indicator LEDs should first flash on both sides. Then the car will indicate left for 3 s: during this time quickly turn the steering on the radio control transmitter fully to the left and the throt tle to full reverse (maximum braking).

Hold the controls in this position until the car starts to indicate right. Then set the controls to their opposite extremes and hold them there until both sides flash again. Now, if the car has an internal combustion engine (and so cannot go in reverse), keep the throttle control on full; if the car has an electric motor, set the throttle to full reverse. Hold this position while both sides are flashing. Configuration is now complete and JP1 can be removed. If you make a mistake during the configuration process, start again from the beginning.

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