Schematic Volt: light

Friday, November 7, 2014

40 LED Bicycle Light

The 555 circuit below is a flashing bicycle light powered with four C,D or AA cells (6 volts). Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during the T1 time interval. The high output level of the 555 timer is 1.7 volts less than the supply voltage.

Adding the LED increases the forward voltage required for the PNP transistor to about 2.7 volts so that the 1.7 volt difference from supply to the output is insufficient to turn on the transistor. Each LED is supplied with about 20mA of current for a total of 220mA. The circuit should work with additional LEDs up to about 40 for each group, or 81 total. The circuit will also work with fewer LEDs so it could be assembled and tested with just 5 LEDs (two groups of two plus one) before adding the others.

Thursday, October 23, 2014

Light Dependent Resistors

LDRs or lightweight Dependent Resistors are terribly helpful particularly in light/dark sensor circuits. Normally the resistance of an LDR is incredibly high, typically as high as a thousand 000 ohms, however once they are illuminated with lightweight resistance drops dramatically.

The animation opposite shows that when the torch is turned on, the resistance of the LDR falls, permitting current to have it.Circuit Wizard software has been used to show, the vary of values of a ORP12, LDR .
When a light-weight level of a thousand lux (bright light) is directed towards it, the resistance is 400R (ohms).

When a light-weight level of ten lux (very low light level) is directed towards it, the resistance has risen dramatically to ten.43M (10430000 ohms).

This is an example of a light-weight sensor circuit :

When the sunshine level is low the resistance of the LDR is high. This prevents current from flowing to the bottom of the transistors. Consequently the LED doesnt lightweight. However, when lightweight shines onto the LDR its resistance falls and current flows into the bottom of the primary transistor and then the second transistor. The LED lights.

The preset resistor will be turned up or right down to increase or decrease resistance, during this means it will build the circuit additional or less sensitive.

Thursday, October 9, 2014

Light to Frequency converter circuit

The circuit is based on TLC555, the CMOS version of famous timer IC NE 555. A photo diode is used for sensing the light intensity.The timer IC is wired in astable mode.The leakage current of the reverse biased photo diode is proportional to the light intensity falling on it.This leakage current charges the capacitance C1.When the capacitor voltage reaches 2/3 of the supply voltage the out put (pin 3) goes low.As a result the capacitor discharges through photo diode .When the capacitor voltage reaches 1/3 the supply voltage the out put (pin 3) of IC goes high.This cycling continues and we get a frequency at pin 3 proportional to the light intensity falling on the photo diode.

Light to Frequency Converter Circuit Diagram & Parts List.

Light to Frequency Converter Circuit Diagram

Notes.

With the given components the frequency varies from 1KHZ @ complete darkness to 24 Khz @ bright sunlight.The frequency range can be changed by using different values for C1.
Use any general purpose photo diode for D1.

Wednesday, September 24, 2014

Emergency Light using Phone Line Circuit Diagram

This is a circuit for emergency lighting with LEDs that uses electricity from the telephone line. Generally the phone line has a DC voltage 48V and somewhere around 20 mA, and when the phone rings, the voltage rises to 96V AC. This works in a way that the phone line will not be busy while the LEDs are turned on and when you pick up the phone, the light goes off and lets you use your phone normally.

Emergency Light using Phone Line Circuit Diagram

Thursday, September 18, 2014

40 LED Bicycle Light

Circuit Source: DIY Electronics Projects

Monday, September 15, 2014

Light Detector

This is a schema diagram of light detector. This schema can be used as a sensor of automatic lamp switch, thic schema also can be used for anti theft alarm schema.

Schematic diagram:

Use variable resistor R1 to adjust the light threshold at which the schema triggers. R1s value is chosen to match the photocells resistance at darkness. The schema uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 to reset the schema. You may used piezo buzzer or LED as output indicator, you may use both of them.

Wednesday, September 10, 2014

Friday, August 15, 2014

Knightrider light system

This is knight rider light system. you all can modify you car like knight rider car through this schema.Use red colour LEDs to get maximum attraction.

NE555 pins

1 GND
2 TRIGGER
3 OUTPUT
4 RESET
5 CONTROL VOLTAGE
6 THRESHOLD
7 DISCHARGE
8 VDD

CD4017 pins

1 Q5
2 Q1
3 Q0
4 Q2
5 Q6
6 Q7
7 Q3
8 GND
9 Q8
10 Q4
11 Q9
12 CO
13 NOT ENABLE
14 CLK
15 RESET
16 VDD

Click to see
4017 IC

Thursday, August 14, 2014

Light sensor component

Electronic components are included in the category of light sensors are as follows:

- LDR
- Photo Transistor
- Photo Diode
- Infrared Receiver

The function of the electronic component is to detect the intensity of light received by the component. The light sensor is often used in electronic equipment such as on television, light a light switch, light intensity measuring instrument.