Simple LED Bike Light Schematic

We know flashing LED lights from the high street shop. But, they were often gave me trouble with flat batteries and lights that fell off. In this case, we make a better one idea using another front wheel, one which has a dynamo already built in the hub. This supplied a nice sine wave of 30 Vpp (at no load). With this knowledge I designed a simple power supply. The transistors that are used are type BD911. These are a bit of an overkill, but there were plenty of these at my school, so that is why I used them. Something a little smaller will also work. The power supply is connected to an astable multi-vibrator. This alternately drives the front light and the rear light. This is the figure of the circuit.

Very Simple Power Failure Light Circuit

This simple circuit has many uses, from lighting up rooms and walkways in the case of a power failure, to monitoring and security uses. This circuit is a very basic power failure lighting circuit based around a relay. Here’s the figure of the circuit;

 

There are many different power failure circuits out there based on 555 timers or transistors but they all have different problems including limited input voltage, price and complexity, and poor backup power. This unit has been designed to work with mains power all the way down to 5 volts, and power 3 LEDs to provide light for a hallway or a child's room in the event of power failure. The PCB includes many simple add-ons and modifications too. This circuit is connected to ac power through J1 then rectified to dc through D1-D4. D5 is a 12 volt zener diode being used along with the resistor R1 and the coil resistance of relay RL1 to regulate the input voltage to 12 volts and C1 is used to help smooth this power. Alternatively a dc voltage of 5 volts or more can be connected directly to J2 and J3, positive to J2 and negative to J3; in this setup the circuit would not need J1, D1-D5, and R1. The relay RL1 is a SPDT 5vDc relay and when power is applied to it, it opens the circuit with the LEDs so they are off as long as power is on if the power goes off, the relay closes the circuit and the battery BAT1 powers the LEDs D6, D7, and D8. In this circuit BAT1 is a 9 volt battery that powers the 3 LEDs through R3; however BAT1 can be many different batteries depending on your needs. J4 is also available in parallel with the LEDs to connect a buzzer or etc.

Simple DC or AC Voltage Indicator Circuit

This circuit is a circuit diagram is not a novelty, but it proved so useful, simple and cheap that it is worth building. When the positive (Red) probe is connected to a DC positive voltage and the Black probe to the negative, the Red LED will illuminate. This is the figure of the circuit;


Reversing polarities the Green LED will illuminate. Connecting the probes to an AC source both LEDs will go on. The bulb limits the LEDs current to 40mA @ 220V AC and its filament starts illuminating from about 30V, shining more brightly as voltage increases. Therefore, due to the bulb filament behavior, any voltage in the 1.8 to 230V range can be detected without changing component values.

Parts:
P1 = Red Probe
P2 = Black Probe
D1 = 5 or 3mm. Red LED
D2 = 5 or 3mm. Green LED
LP = 1220V 6W Filament Lamp Bulb
Source :extremecircuits.blogspot.com

Simple Automotive 12 V Voltage Indicator

This is a design circuit for indicating the voltage in an automotive. This circuit is a simple form of the indicator. This circuit is based on 74HCT04 as controller the circuit. This is the figure of the circuit.


When troubleshooting the 12v electrical system of an automobile, it is nice to have a simple voltage indicator tool instead of a voltmeter. This electronic circuit, hobby circuit is powered by two AA or even two N cells, which will provide enough energy for years of service. The circuit has only two leads. One lead connects to the chassis ground of the car.

The second lead can be sharp tip probe. The circuit will indicate if an automotive electrical circuit has zero volts or 12 volts present. If the voltage is near +12v, a green LED will turn on. If the voltage is near chassis ground a red LED will turn on. If the circuit is open, neither light will light. The circuit draws so little current in the open standby mode that no on/off switch is required.

Simple LED Pilot Circuit

This is a circuit diagram Led pilot using FET. The FET (Field Effect transistor) is ECG312, NTE312 good for up to 30Vdc max. MPF102 that will also work with both, only the max voltage is 25V. This is the figure of the circuit.


Principles of circuit when this is the gate and source associated with, the current behaves as a regulator. In circuits that are on the constant is between 6 and 8 mA at 5 to 30Vdc. Because the set at this time is about 6mA older than the LED will glow a little in the answer. If the diode is added, such as 1N4148 or similar, can be connected to a source of AC-AC 5-20 V (NTE312).

Simple AC Current Indicator Light

This is design circuit for AC indicator. The circuit will indicate the current from the circuit that is used as load of the circuit. The circuit is very simple design circuit. This is the figure of the circuit.


This circuit could be wired into a 120vac power line, which feeds power to any load, ranging from 40 watts to 250 watts. It will turn on a LED light whenever current is being drawn by a load. It is especially useful for remote lights, where you may not be able to see if the lamps are receiving power.

Simple Led Pulse Circuit

This circuit is called LED Pulse. This circuit is a simple design circuit for application the LED. In principle, the operation mode is obtained by the triangular wave generator formed by two op-amps in a very cheap 8 pin IC Dil cases. Q1 ensures current buffering, in order to get a better load drive. This is the figure of the circuit.


R4 & C1 are the components, the circuit where this total time about 4 seconds. If the value of R4 to adopt is under 220K, the pulsing effect of the peculiar effect of flash. Do not supply the circuit with the voltage exceeds 6V. At 6V supply, increase the value of R6 to 100 Ohm.

Part :
R1, R2 = 4K7
R3 = 22K
R4 = 2M2
R5 = 10K
R6 = 47R
C1 = 1µF
D1 = LED
IC1 = LM358
Q1 = BC337

Simple Fuse Monitor and Indicator Circuit

This is a simple design for fuse monitoring circuit. This circuit is work for to check if a fuse has blown without removing it from its holder. This is the figure of the circuit.


The simplicity of this circuit uses just two components, but with just one resistor and an LED this circuit gives visual indication of when a fuse has blown. LED1 is normally off, being "short circuited" by the fuse, F1. Should the inevitable "big-bang" happen in your workshop then LED1 will illuminate and led you know all about it. Please note that the LED will only illuminate under fault conditions, i.e. with a short circuit or shunt on the load. In this case the current is reduced to a safe level by R1.