Posts Tagged ‘IC 7555’

Courtesy Light by 7555 or TS555CN

15 seconds delayed switch-off, A good idea for bedroom lamps
This circuit is intended to let the user turn off a lamp by means of a switch placed far from bed, allowing him enough time to lie down before the lamp really switches off. Obviously, users will be able to find different applications for this circuit in order to suit their needs.

Parts :
R1 = 470R 1/2W
R2 = 100K
R3 = 1M5
R4 = 1K
C1 = 330nF-400V
C2 = 100µF-25V
C3 = 10nF-63V
C4 = 10µF-25V
C5 = 10nF-63V
D1 = 1N4007
D2 = 1N4007
D3 = BZX79C10
D4 = TIC206M
Q1 = BC557
IC1 = 7555 or TS555CN CMos Timer IC
SW1 = SPST Mains suited Switch

Circuit operation:
Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 10Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1 is a CMos 555 timer wired as a monostable, providing 15 seconds on-time set by R3 & C4. When SW1 is closed, IC1 output (pin 3) is permanently on, driving Triac D4 which in turn feeds the lamp. Opening SW1 operates the monostable and, after 15 seconds, pin 3 of IC1 goes low switching off the lamp.

Source: www.redcircuits.com

Brightness Control for small Lamps by IC 555

Switch-mode driven 1.5V bulbs
Portable unit – 3V battery supply
This device was designed on request, to control the light intensity of four filament lamps (i.e. a ring illuminator) powered by two AA or AAA batteries, for close-up pictures with a digital camera. Obviously it can be used in other ways, at anyone’s will.
IC1 generates a 150Hz square wave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow. Bulb LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses increase in width, reaching their maximum amplitude when the potentiometer is rotated fully clockwise. In this way the bulb reaches its full brightness.

Parts:
P1________________470K Linear Potentiometer
R1_________________10K 1/4W Resistor
R2_________________47K 1/4W Resistor (See Notes)
R3__________________1K5 1/4W Resistor
C1_________________22nF 63V Polyester Capacitor
C2________________100µF 25V Electrolytic Capacitor
D1,D2___________1N4148 75V 150mA Diodes
IC1_______________7555 or TS555CN CMos Timer IC
Q1_______________BD681 100V 4A NPN Darlington Transistor
LP1_______________1.5V 200mA Bulb (See Notes)
SW1_______________SPST Switch
B1__________________3V (Two 1.5V AA or AAA cells in series, etc.)

Please read more at the original source: http://www.redcircuits.com/Page63.htm
Thank you.

Related Links Circuits
More circuit Light Switch
More circuit by IC 7555
More circuit Light Control
Dimmer Lamp LDR control with Triac.
Audible Light Sensor by IC 741

Bicycle back Safety Light with IC 555 or 7555

Flashing 13 LED unit, 3V supply Also suitable for jogger/walkers

IC1 is a CMos version of the 555 IC wired as an astable multivibrator generating a 50% duty-cycle square wave at about 4Hz frequency. At 3V supply, 555 output (pin 3) sinking current operation is far better than sourcing, then LEDs D1-D6 are connected to the positive supply rail. In order to obtain an alternate flashing operation, a second 555 IC is provided, acting as a trigger plus inverter and driving LEDs D7-D12. D13 is permanently on.
The LEDs are arranged in a two series display as shown below, with a center LED permanently on. This arrangement and the alternate flashing of the two series of LEDs provide a pseudo-rotating appearance.

Parts:
R1_____________10K 1/4W Resistor
R2,R9,R10_____100K 1/4W Resistors
R3-R8,R11-R16__10R 1/4W Resistors
R17___________150R 1/4W Resistor
C1______________1µF 63V Polyester Capacitor
C2_____________10nF 63V Polyester Capacitor
C3____________100µF 25V Electrolytic Capacitor
D1-D13_____Red LEDs 5mm. or bigger, high efficiency
IC1,IC2________7555 or TS555CN CMos Timer IC
SW1____________SPST Slider Switch
B1_______________3V Battery (2 AA 1.5V Cells in series)

Read more Source : http://www.redcircuits.com/Page24.htm

Related Links
More information about IC 7555
See other circuit on 555 led flasher circuit
See other circuit on bicycle Light
Rear Light After Glow (For Bicycles)
Bicycle tail light flashing
Advanced bicycle lightings