This is the electronic bicycle directional lights circuit that use inexpensive components and is a good substitute to many commercially available versions in the marketplace. This circuit works in an extremely different manner and is convenient to operate.

The bicycle direction indicators circuit works off a 9V PP3 (alkaline-type) battery and is basically a set of two independent free-running oscillators (astable multivibrators) built around four low-power transistors and a few passive components. Both the square-wave oscillators (one built around T1 and T2 and the other built around T3 and T4) drive four red LEDs (LED1 and LED2, and LED5 and LED6, respectively), which blink to indicate the direction of turn. Additional steady-glow LEDs (LED3 and LED4) are incorporated to indicate the working status.

How the Bicycle Directional Signal Lights Works

When switch S1 is flipped to “on” position, DC supply from the battery is extended to the oscillator circuit formed by transistors T1 and T2. Now the left-side oscillator starts oscillating and the visual indicators at the front left (FL) and rear left (RL) start blinking at a rate determined by timing capacitors C1 and C2. Resistors R2 and R3 limit the operating current of LEDs (LED1 and LED2). At the same time, the green LED (LED3) starts glowing to indicate the present direction status.

Similar action happens in the next oscillator circuit built around transistors T3 and T4 when switch S2 is flipped to “on” position. Indicators at the front right (FR) and rear right (RR) start blinking, and at the same time the green LED (LED4) glows to indicate the direction status.

Switch S3 is used for emergency indication. When it is flipped to “on” position, both the oscillators get power supply through diodes D1 and D2. As a result, LED1 through LED6 start working simultaneously. In this condition, all the LEDs blink, except LED3 and LED4, which glow steadily.

Bicycle Directional Lights Assembly

After assembling the circuit on a general purpose PCB, enclose it in a suitable cabinet as shown the following image and mount on the handle bar of the bicycle, preferably at the mechanical centre point.

Connect switch S1 at the left-hand side, S2 at the right-hand side and emergency switch S3 in the middle of the master unit. Now place this master unit at the top of the handle bar and do the essential interconnections using flexible wires. Connect the front indicators (LED1 and LED5) to the left and right side of the handle and similarly rear indicators (LED2 and LED6) can be mounted in the carrier frame of the bicycle.

For the direction indicator, you can use the direction symbol and place it at the centre of the handle, look at above image for reference.

This is the circuit diagram of 3V strobe light miniature. The strobe lights are generally used to create nice looking visual effects in disco halls and auditoria. This post explain how to build the circuit of a battery operated portable miniature strobe light, using inexpensive components.

For convenience and simplicity, an ordinary neon lamp is used here in place of the conventional Xenon tube. The whole gadget can thus be easily mounted in a small cabinet, such as a mains adaptor cover, with a suitable reflector for neon lamp to give a proper look. Because of the electric current need of this circuit is very small, it may be powered by two medium-size dry cells (3V) or Ni-Cd cells (2.4V).

Transistors T1 and T2 in the circuit form a complimentary-pair amplifier. When switch S1 is momentarily depressed, the circuit oscillates because of the positive feedback provided via resistor R2 and capacitor C1 to the base of transistor T1. The sharp pulses in the secondary windings induce a high voltage in primary windings of transformer X1, which in fact is a line driver transformer (used in reverse) generally used in 36cm TV sets.

High voltage pulses induced in primary side are rectified by diode D1 and rapidly charge reservoir capacitor C2 to nearly 300V DC. When switch S1 is released, capacitor C2 holds the voltage level for a finite period while capacitor C3 charges slowly through resistor R3. When voltage across capacitor C3 becomes high enough, neon strikes and the capacitor rapidly discharges through the lamp. When voltage across capacitor C3 falls below the extinguishing potential of neon lamp, it goes off and capacitor C3 starts charging again. This cycle keeps on repeating for a short time, based on the reservoir capacitor C2â€s value.

Warning: The neon lamp flasher section of this 3V strobe light miniature circuit carries dangerously high voltages. All precautions should therefore be taken for protection. Before any repair work, discharge capacitor C2 using a short length of wire with a 100k resistor connected in series. Use this circuit with your own risk.

The current through the LED is not limited to the resistor, but the capacitance of the capacitor. The capacitance can be selected so that the current passing through it could regulate directly after power LED. Since the current leads the voltage by 90?, does not arise (ideally) no power loss of the capacitor and the capacitor is not heated. Reactance capacitor can be easily calculated with the following formula:

where Xc is capacitive reactance in Ohm, pi (3.14), f frequency in Hertz and C the capacitance in Farad.
A capacitor with a capacity of 100nF will have for grid frequency reactance:
1 / (2x3.14x50x10-7) = 31831 Ohm

If you connect this capacitor voltage network, it will be the power flow 230/31831 = 0.0072 A. If we connect in series with the capacitor bridge rectifier with LED, the current has substantially altered.

Resistor R1 has only one task – during off indicator light capacitor discharge and prevent unpleasant “kick” while handling the device off.

Warning: The entire circuit is connected to the high voltage electrical network. Therefore, it is necessary to work at maintaining the necessary caution.

source:http://www.belza.cz/ac-led/kontrol.htm

The work of this circuit is simple. The 400V capacitor, the bridge rectifier, the zener diode and the capacitor 100uF will form the power supply voltage which obtained approx. 9VDC from transformerless power supply design. The integrated 555 and its annexes components generate a train of pulses applied on the triac optocoupler MOC3021 driven intermittently causing the lamp on and off continuously. The triac may be a 2N6073A or TIC226D. By changing the 100K resistor or 1uF capacitor, then the flashing time will changed too. The rectifier bridge may be four 1N4007 diodes or 400v bridge diode with 1A current. The triac should be mounted on a heat sink to prevent over heating.

Warning!!! The entire circuit operates from 220v mains without insulation so the appropriate safety precautions should be taken to minimize the risk. Build this 220V 800W lamp flasher circuit with your own risk.

The game is simple. As stated above, it is a scoring game and the competitor who scores 100 points rapidly (in short steps) is the winner. For scoring, one has the option of pressing either switch S2 or S3. Switch S2, when pressed, makes the counter count in the forward direction, while switch S3 helps to count downwards.

Before starting a fresh game, and for that matter even a fresh move, you must press switch S1 to reset the ci cuit. Thereafter, press any of the two switches, i.e. S2 or S3.

On pressing switch S2 or S3, the counter”s BCD outputs change very rapidly and when you release the switch, the last number remains latched at the output of IC2. The latched BCD number is input to BCD to 7-segment decoder/driver IC3 which drives a common anode display DIS1. However, you can read this number only when you press switch S4.

The sequence of operations for playing the game between, say two players “X” and “Y”, is summarised below:

1. Player “X” starts by momentary pressing of reset switch S1 followed by pressing and releasing of either switch S2 or S3. Thereafter he presses switch S4 to read the display (score) and notes down this number (say X1) manually.
2. Player “Y” also starts by momentary pressing of switch S1 followed by pressing of switch S2 or S3 and then notes down his score (say Y1), after pressing switch S4, exactly in the same fashion as done by the first player.
3. Player “X” again presses switch S1 and repeats the steps shown in step 1 above and notes down his new score (say, X2). He adds up this score to his previous score. The same procedure is repeated by player “Y” in his turn.
4. The game carries on until the score attained by one of the two players totals up to or exceeds 100, to be declared as the winner.

Several players can participate in this game, with each getting a chance to score during his own turn.

Construct the circuit using a multipurpose PCB. Fix the display (LEDs and 7-segment display) on top of the cabinet along with the three switches. The supply voltage for the? circuit is 5V. You may use three batteries with series connection to operate this game scoring display circuit.

This is LED emergency light that will turned on automatically when mains supply fails, and turned off when mains power resumes. This circuit produces highly bright because the use of ultra bright white LEDs. This circuit also has its own battery charger. When the battery is fully charged, the charging process will stop automatically.

Components List:

R1           = 180R - 1/2W
R2           = 1.2K
R3 - R14     = 100R - 1/2W
R15          = 1K - 1/2W
R16          = 16R/5W
VR1          = 2.2K
C1           = 1000uF/25V
D1-D5        = 1N4007
D6           = 6.8V - 0.5W Zener
LED1 - LED12 = Ultrabright White LEDs
T1           = BC548
T2           = BD140
B1           = 6V - 4.5Ah Rechargable Battery
IC1          = LM317
T1           = 9VAC-Transformer

The circuit contains two important blocks: charger power supply section and LED driver section.

Charger Section

The charger power supply section is built around 3-terminal adjustable regulator IC LM317 (IC1), while the LED driver section is built around transistor BD140 (T2).

In the charger power supply section, input AC mains is stepped down by transformer X1 to deliver 9V, 500 mA to the bridge rectifier, which comprises diodes D1 through D4. Filter capacitor C1 eliminates ripples. Unregulated DC voltage is fed to input pin 3 of IC1 and provides charging current through diode D5 and limiting resistor R16. By adjusting preset VR1, the output voltage can be adjusted to deliver the required charging current.

When the battery gets charged to 6.8V, zener diode ZD1 conducts and charging current from regulator IC1 finds a path through transistor T1 to ground and it stops charging of the battery.

LED Driver

In this LED emergency light circuit, the LED driver section uses a total of twelve 10mm white LEDs. All the LEDs are connected in parallel with a 100-ohm resistor in series with each. The common-anode junction of all the twelve LEDs is connected to the collector of pnp transistor T2 and the emitter of transistor T2 is directly connected to the positive terminal of 6V battery. The unregulated DC voltage, produced at the cathode junction of diodes D1 and D3, is fed to the base of transistor T2 through a 1K ohm resistor.

When mains power is available, the base of transistor T2 remains high and T2 does not conduct. Thus LEDs are off. On the other hand, when mains fails, the base of transistor T2 becomes low and it conducts. This makes all the LEDs (LED1 through LED12) glow.

The mains power supply, when available, charges the battery and keeps the LEDs off as transistor T2 remains cut-off. During mains failure, the charging section stops working and the battery supply makes the LEDs glow.

You can construct this LED emergency light circuit on a general-purpose PCB and mount the circuit in a plastic with enough space for battery and switches. Mount the LEDs on the cabinet such that they light up the room. A hole in the cabinet should be drilled to connect 230V AC input for the primary of the transformer.

Note: Since the transistor T2 can deliver up to 1.5A with proper heatsink, you may use more LEDs provided the total current consumption does not exceed 1.5A. Standar LED current consumption is about 20mA only.

This is the circuit diagram of 230V automatic night lamp based photo resistor to sensing the light environment. When the condition is dark enough, the one or more lamps will be turned on and when the condition is bright enough, then the lamps will be turned off.

Q1 and Q2 form a trigger device for the SCR, providing short pulses at 100Hz frequency. Pulse duration is set by R2 and C1.

When the light hits? the photo resistor (R1) then it will has very low resistance value, almost shorting C1 and preventing circuit operation. When R1 is in the dark, its resistance value becomes very high thus enabling circuit operation.

Circuit Notes:

• Variable Resistor R3 used for fine setting of operating threshold and R2 value can be raised to 150K maximum.
• Several lamps can be connected in parallel to the circuit, but total power dissipation of the load should not exceed about 300 – 500W.
• PL1 can be omitted and the input mains supply wires connected in parallel to any switch controlling lamps. In this case, if the switch is left open, the circuit will be able to drive the lamps; if the switch is closed, the lamps will illuminate and the circuit will be by-passed.

Parts List:
R1 = Photo resistor (any type)
R2 = 100K 1W Resistor
R3 = 200K 1/2W Trimmer Cermet
R4,R7 = 470R 1/4W Resistors
R5 = 12K 1/4W Resistor
R6 = 1K 1/4W Resistor
C1 = 10nF 63V Polyester Capacitor
D1 = TIC106D 400V 5A SCR
D2-D5 = 1N4007 1000V 1A Diodes
Q1 = BC327 45V 800mA PNP Transistor
Q2 = BC337 45V 800mA NPN Transistor
SK1 = Female Mains socket
PL1 = Male Mains plug & cable

This circuit come from redcircuit.com

Attention! The circuit is directly connected to 230Vac electric mains, then some components in the circuit board are subjected to lethal potential with high risk!. Avoid touching the circuit when plugged and enclose it in a plastic box for security purpose.

This is the circuit diagram of Clap On / Off Switch. The circuit allows you to operate your lighting or any circuit device which use 24V / 3A maximum supply, simply by clapping your hands.?It has a relay output that can be used to turn external devices on/off.? This circuit is good and ideal for disabled or elderly people.

Circuit Features:

• good immunity against surrounding noises
• ‘1-clap’ or ‘2-clap’-mode selection
• ‘2-clap’-mode features built-in safety turn-off timer (approx. 5h)
• output relay ‘pulse’ or ‘toggle’ selection
• microprocessor-controlled
• output relay with LED indicator

Circuit Specifications:

• Supply 12Vdc / 150mA i.e. mains adapter (Order Code 660.446UK)
• Outputs 1 x SPDT Relays
• Output Load 3 Amps @ 24V max.

Notes:

• This circuit available in kit, you can order the kit at quasarelectronics.co.uk, the circuit copyright belongs to them.
• To switch 220V AC, you may try to find suitable relay meet your requirement.

This is the traffic baton circuit which available in two versions that are traffic baton with LED flasher and traffic baton with bulb flasher. Both the circuits powered with a 6V, 4.5Ah rechargeable battery, which is clipped to the operator”s waistband. This circuit which come from EFY mag, will help the police or someone to regulate the traffic with hand signals at night or in dark condition. Since their hand signals may not be visible at night, it is necessary to have some illuminated direction indicator.

The image #1 displays the circuit of traffic baton with LED flasher. It uses an astable multivibrator to flash the LED, it similar to flipflof circuit. The “on” time of the LED cluster is about 108 milli seconds and “off” time is around 105 milliseconds. The frequency is around 5 Hz. A diode is wired in series with the base of BD140 to increase the forward voltage in order to ensure that when BD139 conducts, BD140 is cut-off. Select the LED which consumes low current (20 mA or so) but flashes bright.

The image #2 displays the circuit of the trafic baton with bulb flasher. Similar with LED flasher version, the timer NE555 is wired as an astable multivibrator. The “on” period of flashing bulb is around 344 milliseconds and “off” period is around 329 milliseconds. The frequency is around 1.5 Hz. Bulb-driver transistors 2N3053/ BD139 and 2N2905/BD140 are used to light up the lamp. Two diodes are used in series with the base of 2N2905 to increase the forward voltage in order Bto ensure that when BD139 is conducting, BD140 is cut-off. Slide switch S2 is used to change the colour status of the flashing bulb.

Build the LED flasher and bulb flasher circuits on separate general- purpose PCBs. Place the LED flasher in a transparent acrylic pipe as displayed in above images. The bulb flasher circuit can be enclosed in another transparent acrylic pipe. Slide switches and red and green acrylic sheets are used for appropriate colour emissions.

Good luck.

1. The first part consists of? IC1 (555), IC2 (74LS164), IC3 (74LS86), IC4 (74LS00) and the associated pars. These generate a randomly changing train of pulses.
2. The second part of the circuit?comprises SCR1 (C106), an electric bulb connected between anode of SCR1 and mains live wire, and gate trigger circuit components. It is basically half-wave AC power being supplied to the electric bulb.
3. The third part is the power supply adapter circuit to produce regulated 5V DC from 230V AC for random signal generator. It comprises a stepdown transformer (X1), full-wave rectifier (diodes D3 and D4), filter capacitor (C9), followed by a regulator (IC5).

The random signal generator of the circuit is built around an 8-bit serial in/parallel out shift register (IC2). Different outputs of the shift register IC pass through a set of logic gates (N1 through N5) and final output appearing at pin 6 of gate N5 is fed back to the inputs of pins 1 and 2 of IC2. The clock signal appears at pin 8 of IC2, which is clocked by an astable multivibrator configured around timer (IC1). The clock frequency can be set using preset VR1 and VR2. It can be set around 100 Hz to provide better flickering effect in the bulb.

The random signal triggers the gate of SCR1. The electric bulb gets AC power only for the period for which SCR1 is fired. SCR1 is fired only during the positive half cycles. Conduction of SCR1 depends upon the gate triggering pin 3 of IC2, which is random. Thus, we see a flickering effect in the light output.

Assemble the circuit on a generalpurpose PCB and enclose it in a suitable case. Fix bulb and neon bulb on the front side of the cabinet. Also, connect a power cable for giving AC mains supply to the circuit for operation. The circuit is ready to use.

Be careful since this circuit uses home electrical installation? 220V AC voltage.