sokrat
Full Member level 5
bt139 bc547b circuits
OPERATION
The circuit consists of 2 sections:
1) Oscillator: The oscillator is built around IC555 wired in astable mode. The frequency of this oscillator is around 1 Hz (or slightly less than that) which can be increased further by decreasing the value of potentiometer VR1. The oscillator frequency determines the speed of effect. Higher the frequency, higher will be the effect speed.
2) Sequencer circuit: The sequential lighting of bulbs is achieved using Jhonson Counter IC 4017 which has 10 decoded outputs. The output of 4017 increments by one on rising edge of each clock pulse from IC555. In the circuit the fifth output Q4 of 4017 is connected to its reset pin to reset the sequence after every four clock pulses. Here only four channels are shown but it can be extended upto 10 channels using all the outputs of 4017. In this case the reset need to be connected to Ground. For channels less than 10 the output one greater than required number of channels should be connected to reset pin to reset the cycle as soon as counter counts one greater than the required channels.
The output of 4017 drives the base of NPN transistors (BC547) through 1k resistors. The LED in the collector loop of each transistor indicates the active channel. The emitter current of each transistor further drives the gate of Triacs (BT139) thereby turning them ON and supplying power to the lamp loads. Those who have 120V AC mains in their countries can also use this circuit without any changes. Many number of bulbs can be connected in parallel on each channel provided the maximum load on each channel does not exceed 3500W for 220V operation and 1760W for 110V operation.
NOTE: DO NOT TOUCH ANY COMPONENT OF THE CIRCUIT WHEN IT IS ACTIVE AS IT MAY BE AT A VERY HIGH POTENTIAL AND MAY PROVE FATAL. I DO NOT GIVE GURANTEE OF ANY KIND. EXPERIMENT AT YOUR OWN RISK.
OPERATION
The circuit consists of 2 sections:
1) Oscillator: The oscillator is built around IC555 wired in astable mode. The frequency of this oscillator is around 1 Hz (or slightly less than that) which can be increased further by decreasing the value of potentiometer VR1. The oscillator frequency determines the speed of effect. Higher the frequency, higher will be the effect speed.
2) Sequencer circuit: The sequential lighting of bulbs is achieved using Jhonson Counter IC 4017 which has 10 decoded outputs. The output of 4017 increments by one on rising edge of each clock pulse from IC555. In the circuit the fifth output Q4 of 4017 is connected to its reset pin to reset the sequence after every four clock pulses. Here only four channels are shown but it can be extended upto 10 channels using all the outputs of 4017. In this case the reset need to be connected to Ground. For channels less than 10 the output one greater than required number of channels should be connected to reset pin to reset the cycle as soon as counter counts one greater than the required channels.
The output of 4017 drives the base of NPN transistors (BC547) through 1k resistors. The LED in the collector loop of each transistor indicates the active channel. The emitter current of each transistor further drives the gate of Triacs (BT139) thereby turning them ON and supplying power to the lamp loads. Those who have 120V AC mains in their countries can also use this circuit without any changes. Many number of bulbs can be connected in parallel on each channel provided the maximum load on each channel does not exceed 3500W for 220V operation and 1760W for 110V operation.
NOTE: DO NOT TOUCH ANY COMPONENT OF THE CIRCUIT WHEN IT IS ACTIVE AS IT MAY BE AT A VERY HIGH POTENTIAL AND MAY PROVE FATAL. I DO NOT GIVE GURANTEE OF ANY KIND. EXPERIMENT AT YOUR OWN RISK.