Showing posts with label flasher. Show all posts
Showing posts with label flasher. Show all posts
Sunday, November 2, 2014
Low Power LED Flasher
It doesnt get much simpler than this circuit. Four components counting the battery!
How can an LED be illuminated by a 1.5V circuit, when the forward voltage of an LED is about 2V? The LM3909 uses the 100uF capacitor as a charge reservoir, building up a voltage of about 2V before discharging the cap through the LED.
This circuit is used in emergency flashlights on airplanes and in other public places. Though you may not have known it till now, the LM3909 is everywhere!
Low Power LED Flasher
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How can an LED be illuminated by a 1.5V circuit, when the forward voltage of an LED is about 2V? The LM3909 uses the 100uF capacitor as a charge reservoir, building up a voltage of about 2V before discharging the cap through the LED.
This circuit is used in emergency flashlights on airplanes and in other public places. Though you may not have known it till now, the LM3909 is everywhere!
Low Power LED Flasher
Saturday, November 1, 2014
Simple Multivibrator Flasher
The diagram basic 2 LED astable multivibrator flasher built by Mary. She chose to use 2 different colored LEDs and the red LED is clear when unlit. It is quite bright when lit compared to the yellow LED despite the fact that it only draws 0.5 mA more. The bread boarded test circuit was powered by a new 9 volt battery and was regulated by a L78L05 (in a TO-92 package as shown in the schematic). The 5 volt regulator was used to avoid exceeding the reverse breakdown voltage of the 2N3904. This topic will be discussed a little later on.
470 ohm current dropping resistors were chosen to keep the collector current draw less than 10 mA. The LEDS were bright enough to see well in dim lighting. You may change this resistor "R" value (lower R = brighter), but do not exceed the maximum current rating for the LED or transistor (this is more applicable to higher voltage multivibrators). You may also place 2 or more LEDs in series on each half of a multivibrator, however, the current dropping resistor may need to be reduced to maintain brightness. Consider using a power supply as opposed to battery power for your flashers.
To change the pulse (oscillation) frequency, you can change the base resistor or the timing capacitor values. For example, increasing the capacitor or the base resistor values will increase the time OFF per cycle and thus reduce the oscillation frequency. The oscillation frequency is 60 divided by the sum of the time OFF for each half of the multivibrator. Do not feel you have to use the same timing capacitor for each 1/2 of the multivibrator. Multivibrators with different timing components on each 1/2 are termed asymmetrical.
Over time, some builders sent me emails that they could not get their multivibrator to run. I problem-solved with them and discovered many problems including bad parts, bread boarding errors, the oscillation frequency was too fast to observe, transistors were not saturated during their ON time and failure of the transistors due to excessive current or perhaps even reverse emitter-base breakdown.
470 ohm current dropping resistors were chosen to keep the collector current draw less than 10 mA. The LEDS were bright enough to see well in dim lighting. You may change this resistor "R" value (lower R = brighter), but do not exceed the maximum current rating for the LED or transistor (this is more applicable to higher voltage multivibrators). You may also place 2 or more LEDs in series on each half of a multivibrator, however, the current dropping resistor may need to be reduced to maintain brightness. Consider using a power supply as opposed to battery power for your flashers.
To change the pulse (oscillation) frequency, you can change the base resistor or the timing capacitor values. For example, increasing the capacitor or the base resistor values will increase the time OFF per cycle and thus reduce the oscillation frequency. The oscillation frequency is 60 divided by the sum of the time OFF for each half of the multivibrator. Do not feel you have to use the same timing capacitor for each 1/2 of the multivibrator. Multivibrators with different timing components on each 1/2 are termed asymmetrical.
Over time, some builders sent me emails that they could not get their multivibrator to run. I problem-solved with them and discovered many problems including bad parts, bread boarding errors, the oscillation frequency was too fast to observe, transistors were not saturated during their ON time and failure of the transistors due to excessive current or perhaps even reverse emitter-base breakdown.
Wednesday, September 3, 2014
Power Flasher
Derived from the Two-wire Lamp Flasher design, hosted on RED Free Circuit Designs since 1999, this astonishingly simple schema allows one or two powerful 12V 21W car bulbs to be driven in flashing mode by means of a power MosFet.Devices of this kind are particularly suited for road, traffic and yard alerts and in all cases where mains supply is not available but a powerful flashing light is yet necessary.
Parts:
R1______________6K8 1/4W Resistor
R2____________220K 1/4W Resistor
R3_____________22K 1/4W Resistor
C1____________100µF 25V Electrolytic Capacitor
C2_____________10µF 25V Electrolytic Capacitor
D1___________1N4002 100V 1A Diode
Q1____________BC557 45V 100mA PNP Transistor
Q2___________IRF530 100V 14A N-Channel Hexfet
LP1___________One 12V 21W Car Filament Bulb or two wired in parallel (See Notes)
SW1___________SPST Switch (3 Amp minimum)
Notes:
* Flashing frequency can be varied within a limited range by changing C1 value.
* As high dc currents are involved, please use suitably sized cables for battery and bulb(s) connections.
Read More..
Parts:
R1______________6K8 1/4W Resistor
R2____________220K 1/4W Resistor
R3_____________22K 1/4W Resistor
C1____________100µF 25V Electrolytic Capacitor
C2_____________10µF 25V Electrolytic Capacitor
D1___________1N4002 100V 1A Diode
Q1____________BC557 45V 100mA PNP Transistor
Q2___________IRF530 100V 14A N-Channel Hexfet
LP1___________One 12V 21W Car Filament Bulb or two wired in parallel (See Notes)
SW1___________SPST Switch (3 Amp minimum)
Notes:
* Flashing frequency can be varied within a limited range by changing C1 value.
* As high dc currents are involved, please use suitably sized cables for battery and bulb(s) connections.
Monday, September 1, 2014
Ringing phone light flasher
This schema can be used to glow a bulb or turn a alarm when the phone rings.Using this schema nuissence of telephone ring at night can be avoided.
When the telephone rings the line voltage rises to 72 volts.At this time the LED in the opto-coupler glows and the transistor conducts. Due to this the transistor Q1 conducts.This makes the relay ON.The load connected to the relay whether bulb or bell turns ON.
Notes.
* Assemble the schema diagram on a good quality PCB or common board.
* Use a 5V DC power supply for powering the schema.
* The load can be connected through NC1,NC2 & C points of the relay.
Monday, August 18, 2014
Flasher for bike
Here I like to give you a very useful schema.This is a flasher for your bike this schema can be operated with 6V (4 x1.5 batteries) .You can control flash duration with 5K VR and flash interval can be adj es with 100K
Note
# Build this schema on a PCB
#Use 1.5 x 4 batteries to power this (6V)
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