LED brightness control circuits

Lighting Circuits Diagram | By: Diagram mania

It’s easy to alter the brightness of an LED simply by varying the current through it. Or you can keep the current constant at a fairly high value and vary the brightness by varying the percentage of time for which the LED is on. In other words, use pulse width modulation to control the brightness. […]

Control electrical appliances using PC

Uncategorized | By: Diagram mania

Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment . The interface circuit shown in the figure is drawn […]

Flashy Christmas Lights

Uncategorized | By: Diagram mania

 This simple and inexpensive circuit built around a popular CMOS hex inverter IC CD4069UB offers four sequential switching outputs that may be used to control 200 LEDs (50 LEDs per channel), driven directly from mains supply. Input supply of 230V AC is rectified by the bridge rectifiers D1 to D4. After fullwave rectification, the average […]

TV remote control Blocker

Uncategorized | By: Diagram mania

Just point this small device at the TV and the remote gets jammed .   The circuit is self explanatory . 555 is wired as an astable multivibrator for a frequency of nearly 38 kHz. This is the frequency at which most of the modern TVs receive the IR beam . The transistor acts as a […]

Ultrasonic Pest Repeller

Uncategorized | By: Diagram mania

It is well know that pests like rats, mice etc are repelled by ultrasonic frequency in the range of 30 kHz to 50 kHz. Human beings can’t hear these high-frequency sounds. Unfortunately, all pests do not react at the same ultrasonic frequency. While some pests get repelled at 35 kHz, some others get repelled at […]

Programmable Digital Code Lock

Digital Circuit | By: Diagram mania

A programmable code lock can be used for numerous applications in which access to an article/gadget is to be restricted to a limited number of persons. Here is yet another circuit of a code lock employing mainly the CMOS ICs and thumbwheel switches (TWS) besides a few other components. It is rugged and capable of […]

Pot plant water tester

Tester Circuits | By: Diagram mania

This simple device checks if their is water in a pot plant. You stick the two probes(paperclips)into the pot plant and if the LED lights, it means there is water in the pot plant. You need to adjust the 47k potentiometer to set the level at which the LED goes on.    

Light flasher/blinker circuit diagram

Lighting Circuits Diagram | By: Diagram mania

This is a very basic circuit for flashing one or more LEDS and also to alternately flash one or more LEDs. It uses a 555 timer setup as an astable multivibrator with a variable frequency. With the preset at its max. the flashing rate of the LED is about 1/2 a second. It can be […]

automatic dual output display circuit diagram

Uncategorized | By: Diagram mania

This circuit lights up ten bulbs sequentially, first in one direc- tion and then in the opposite direction, thus presenting a nice visual effect. In this circuit, gates N1 and N2 form an oscillator. The output of this oscillator is used as a clock for BCD up/down counter CD4510 (IC2). Depending on the logic state […]

Automatic room lights circuit diagram

Uncategorized | By: Diagram mania

 An ordinary automatic room power control circuit has only one light sensor. So when a person enters the room it gets one pulse and the lights come “on”. When the person goes out it gets another pulse and the lights go “off”. But what happens when two persons enter the room, one after the other? […]