8 Random Flashing Leds Circuit

This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of the LEDs would normally be the display segments, the eighth LED is driven by an output that is normally used for driving further counters. The table below shows the sequence for the LEDs. You can use less than eight LEDs if you wish and the table may help you decide which ones to use for your purpose.

Color Organ

I have had many requests for this circuit. It was a very popular unit years ago. The basic idea of the project is to make different colored bulbs light at different frequencies of music. The circuit connects to the speaker outputs of your stereo or to the back of your speaker. The music passes through the transformer and the volume level is adjusted by the 5k ohm pot. Each light bulb is turn on by a different frequency of sound based on the resistor & capacitor combination in the gate circuit of the SCR. If the resistors R1, R2, or R3 are changed, the frequency of sound that will trigger the SCR will change. The isolation transformer is for protection.

Stun Gun Circuit

The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.

- The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
- The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.

Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.

Sun-Up Alarm

The Sun-Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine) The sun shining on this device will provide a high to one of the NAND gates. This will cause another NAND gate to oscillate which will drive another gate to output a 100hz tone. The transistor provides drive for the speaker.

Tutorial - How Lightning Works?

How lightning works?
clouds causes the charges to separate, there is a conductive path.


Lightning and atmospheric electricity
a historical essay on lightning research, access to data from the lighting teams, learn about LIS, OTD, LMS, an overview of field programs.


Museum of electricity - Lightning
what causes lightning?, what causes thunder?, the global electric circuit.


Lightning weather eye
what is lightning, introduction of lightning, experiment, safety, quiz.show how science relates to weather by using something as simple as static electricity.


Space Image
apolo 13 on it's way to the moon, the final frontier, grand canyon, hurricane gladys from space, computer rendering of the international space station, MIR space station, pipe dark nebula.


Lightning Boy
a collection of the current and past advantures, freelance severse weather, storm, lightning


Lightning safety
free tutorial for lightning safety


Lightning Animation
http://www.chunder.com/ski/lightanim.html

Lightning Detector
what is lightning detector, lightning detectors vs. weather radar, aviation use., personal lightning detectors.


useful links
http://www.mos.org/sln/toe/lightning.html
http://www.peter-thomson.co.uk/tornado/Lightning.html

Strobe Light Circuit

The way that this circuit works is as follows. The AC line voltage is rectified by D1 and D2 which connects to a voltage doubler circuit made up of the two 22uf capacitors. The Flash Freq. Pot and the 10uf capacitor charge up which triggers the Diac and causes the triac to turn on. This allows the trigger transformer T1 to send a very High Voltage to the flash tube and lighting it. The flash timing is adjusted by the flash freq. pot.