Showing posts with label flasher. Show all posts
Showing posts with label flasher. Show all posts
Thursday, September 25, 2014
Simple Flasher Circuit Using Unijunction Transistor
This circuit will operate reliably from noisy or fluctuating power supplies and unlike many multivibrator circuits is inherently self-starting when power is applied.
In this flasher circuit unijunction transistor G1 is used as a relaxation oscillator supplying a continuous train of pulses to the gates of the SCRs. Assume that SCR2 has been triggered into conduction and that lamp 2 is energized. The next trigger pulse from O1 triggers SCR1, this discharges C2 and the resultant commutation pulse turns off SCR2. The resistor R2 in the anode of SCR1 is of a value high enough to prevent SCR1 from latching on. SCR2 is re-triggered by the next triggering pulse from O1. Using the component values shown, the flash rate of this circuit is adjustable by R2 from 35 to 150 flashes a minute.
In this flasher circuit unijunction transistor G1 is used as a relaxation oscillator supplying a continuous train of pulses to the gates of the SCRs. Assume that SCR2 has been triggered into conduction and that lamp 2 is energized. The next trigger pulse from O1 triggers SCR1, this discharges C2 and the resultant commutation pulse turns off SCR2. The resistor R2 in the anode of SCR1 is of a value high enough to prevent SCR1 from latching on. SCR2 is re-triggered by the next triggering pulse from O1. Using the component values shown, the flash rate of this circuit is adjustable by R2 from 35 to 150 flashes a minute.
Tuesday, August 19, 2014
Simple Astable 555 Timer IC Flasher
For a lower parts count than the 2 transistor multivibrators, 2 LEDs can be alternately flashed with a 555 integrated schema configured as shown in Schematic 2. I chose the combination of a 2K2 and a 47K resistor to determine the oscillation frequency along with the 10 uF capacitor connected to pins 2 and 6. You can practically change the (R Speed) 47K value to between 10K and 100K or more. Greater resistance = lower speed. You may also wish to connect up a 100K or so potentiometer instead of the 47K resistor for a variable speed version. Additionally, the 10 uF capacitor value can be changed. Feel free to experiment.
Although, alternately flashing LEDs is great for the beginner to electronics, the basic one ON, one OFF schema gets boring quickly. In the next section, we will try to improve the look and try to approximate a flash like a police car (within limits).
Although, alternately flashing LEDs is great for the beginner to electronics, the basic one ON, one OFF schema gets boring quickly. In the next section, we will try to improve the look and try to approximate a flash like a police car (within limits).
Monday, August 18, 2014
Brakelight Flasher
This is basically a flasher schema modified to turn on and off a bulb instead of a LED. It uses a 555 timer IC working as an astable multivibrator. The flashing rate can be varied from very fast to a maximum of once in 1.5 sec by varying the preset VR1.
The ON time of the schema is given by:
TON= 0.69xC1x(R1 + VR1) second
and the OFF time is:
TOFF= 0.69xC1xVR1 second
You can increase the value of C1 to 100uF to get a slower flashing rate of upto once in 10 sec.
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The ON time of the schema is given by:
TON= 0.69xC1x(R1 + VR1) second
and the OFF time is:
TOFF= 0.69xC1xVR1 second
You can increase the value of C1 to 100uF to get a slower flashing rate of upto once in 10 sec.
Saturday, August 9, 2014
230V Flasher Circuit diagram
This schema operates with 230v.you can use this schema to decorate your parties.I think this will be a wonderful schema to you all.This schema was taken from my old schema book called 100 schema book.Here DIAC ER 900 and Triac BTW 11-400.
Note:
# Be careful when you deal with 230V
# Build this schema on a PCB
# Use only mentioned values.
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