Switched ON Bike Lamp circuit diagram:

Component part list:

This switched ON bike lamp circuit was primarily intended to permit automatic switch-on of push-bike lights when it gets dark. Naturally, it might be applied for any other purpose involving one or more lamps to be switched on and off depending of light intensity. Power could be supplied by any kind of battery suitable to be fitted in your bike and having a voltage within the 3 to 6 Volts range. The Photo resistor R1 needs to be fitted into the box containing the total circuit, but a hole should be created in a convenient side of the box to allow the light hitting the sensor. Trim R2 until the desired switching threshold is reached. The setup will require some experimenting, but it ought to not be hard.

Bike Lamp circuit notes:

• In this circuit, the maximum electric current and voltage delivered to the lamp(s) are limited primarily by R6 (that can’t be omitted if a clean and reliable switching is expected). Consequently, the Ohm’s Law should be applied to calculate the ideal voltage and current values of the bulbs.
• At 3V supply, R6 value may be lowered to 1 or 0.five Ohm and the operating voltage of the bulbs should be chosen accordingly, by applying the Ohm’s Law. Example: Supply voltage = 3V, R6 = 1R, total current drawing 600mA. Decide on 2.2V bulbs as the voltage drop caused by R6 will probably be 0.6V.
• At 3V supply, R5 value should be changed to 100R.
• As an example: at 6V supply, one or much more 6V bulbs having a total current drawing of 500mA can be applied, but for a total current drawing of 1A, 4.5V bulbs need to be chosen, as the voltage drop across R6 will become 1.5V. In this case, R6 should be a 2W type.
• Stand-by current is much less than 500uA, provided R2 value following trimming is set at about 5K or greater: for that reason, the power switch SW1 could be omitted. If R2 value is set below 5K the stand-by current will enhance substantially.

Switched ON Bike Lamp circuit source: redcircuit.com

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This is the circuit diagram of white line follower toy. The actuator of the toy is the DC motor. This circuit can be used for?a toy car to follow a white?line, this circuit also known as very simple robot: “line follower without microcontroller”. The motor is either a?3v type with gearing to?steer the car or a rotary?actuator or a servo motor.

How the circuit work..?

When equal light is detected by the photo resistors the voltage on the base of the first transistor will be mid rail and the circuit is adjusted via the 2k2 potensiometer so the motor does not receive any voltage. When one of the LDR’s receives more (or less) light, the motor is turned on / activated. And the same thing will be happen when the other LDR receives less or more light.

You can see the below video as the result of this circuit project:

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Here the simple schematic of multitone siren alarm circuit. This multitone siren is effective for reverse horns, burlgar alarms, and many others. It generates five various audio tones and is much more earcatching than a single-tone siren.

The circuit is constructed around well known CMOS IC 4060 as oscillator-cum-divider and small audio amplifier chip LM386. IC 4060 is utilized as being the main part of multitone generator. A 100uH inductor is utilized at the input of IC 4060. So it oscillates within the assortment of about 5MHz RF. IC 4060 itself separates RF signals into AF and ultrasonic ranges. The audio signals of different frequencies are obtainable at pins 1, 2, 3, 13 and 15 of IC 4060 (IC1). These multifrequency signals are mixed and fed to the audio amplifier assembled close to IC LM386.

The output of IC2 is fed to the speaker via capacitor C9. If you need louder sound, use power amplifier circuit using TBA810 or TDA1010.

Only five outputs of IC1 are put to use right here since the other five outputs (pins 4 through 7 and 14) generate ultrasonic signals, that are not audible.

You may assemble the circuit on a general purpose Printed CIrcuit Board (PCB) and enclose in a appropriate cabinet. Regulated 6V-12V (or possibly a battery) could be utilized to supply the circuit to be work.

PDF version: Multitone siren alarm circuit

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Here the simple traffic light controller which is could be used to educate kids rudiments of traffic light guidelines. The circuit utilizes easily available electronic parts. It generally consists of rectifier diodes (1N4001), a 5V regulator 7805, two timers circuit using IC 555, two relays (5V, single-changeover), three 15W, 230V light bulbs and also several discrete parts.

Mains electrical power is stepped down by transformer X1 to provide a secondary output voltage of 9V, 300 mA – AC. Then the transformer output current is rectified by a full-wave bridge rectifier composed of diodes D1 through D4, filtered by capacitor C1 and also regulated by IC 7805 (IC1).

IC2 is wired as a multivibrator with ‘on’ and ‘off’ periods of about 30 seconds each with the part values determined. Once mains power switch is turned on, pin 3 of IC2 goes high for 30 seconds. This, in turn, energises relay RL1 via transistor T1 and the red bulb (B1) glows through its normally-open (N/O) contact. At the same time, mains power is turned off from the pole of relay RL2.

As the ‘on’ time of IC2 ends, a triggers IC3 through C5. IC3 is set up as a monostable with ‘on’ time of about 4 seconds, which indicates pin 3 of IC3 will stay high for this period of time and energise relay RL2 through driver transistor T2. The amber bulb (B2) thus lightings up for 4 seconds.

Immediately after 4-second time period of timer IC3 at pin 3 lapses, relay RL2 de-energises and also the green bulb (B3) lights up for the rest of ‘off’ period of IC2, which is about 26 seconds. The green bulb is turned on through the normally closed (N/C) contacts of relay RL2.

So when mains electrical switch is turned on, red light will light up for 30 seconds, amber for 4 seconds and green for 26 seconds.

You can easily build this circuit on a general purpose PCB and enclose in a protected box. The box needs to have sufficient area for installing transformer X1 and also two relays. It could be installed near 230V AC, 50Hz power supply or mounted on the PVC tube applied in assembly of the traffic light box.

Design of the traffic light container box is demonstrated in following image:

A stout cardboard box of 30x15x10cm3 is needed for housing the lights. To make certain durability, work with a 10x45cm2 plywood plate having 1.5 centimeters thickness and also secure onto it three light outlets and the box utilizing nuts and bolts or screws.

Make three tubes of thin aluminium sheet, which is easily offered in equipment stores. The inner diameter of aluminium tubes ought to be such that these can well match on the light outlets. Working with a sharp knife, make holes opposite the outlets carefully. Wire the outlets at the back and take the cables out through the PVC tube.

To begin with, fix three 15W light bulbs (B1 through B3) and then press on the tubes. Support the other ends of the tubes in the holes made on the front panel of cardboard box. Sandwich gelatine papers of the three colors in between two sheets of cardboard and fix over the tubes. The visibility of red, amber and also green lights enhances with their installation on the tubular shape.

Simple traffic light controller circuit diagram

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Components List:

R1,R5___________ 4.7K
R2______________ 47K
R3______________ 10K
R4______________ 100K
Rx______________ *see text

C1,C4__________ 100uF/25V, electrolytic
C2,C3__________ 0.01uF (10nF), ceramic
T1_____________ 2N3702 (NTE159, TUP, etc.)
IC1,IC2________ LM/NE555, MC1455P, etc
LS_____________ Loudspeaker

This alarm circuit uses timer IC to generate frequency. The circuit has wide range supply voltage 5V to 15V DC.

*The Loudspeaker LS and the resistor marked “Rx” should be together 75 ohms. If you have a standard 8-ohm speaker then Rx is 67 ohms. The nearest value is 68 ohms. So for a 8 ohm loudspeaker Rx is 68 ohms. For a 4 ohm loudspeaker Rx is 71 ohms, for a 25 ohm loudspeaker Rx is 50 ohms, etc.

circuit diagram by Tony van Roon,
source: http://www.sentex.ca/~mec1995/circ/wailing.htm

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IC KS5401 will generate the sound, while TR D438 used to be amplified the audio signal. I’ve try to find the datasheet for KS5401, but unfortunately I did not find it.

Please make sure you find the KS5401 first before you build this circuit.

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Resistor R1 biases the potentiometer to match the input range of U1. Full counter-clockwise rotation of the pot corresponds to maximum-speed reverse rotation of the motor. Mid-scale on the pot corresponds to motor off, and full clockwise rotation of the pot produces maximum-speed forward rotation in the motor.

The characteristics of a given motor may allow you to eliminate the amplifier’s output filter (L1, L2, C1, and C2). But, unless the control circuitry shown is located near the motor, you should include the filter to reduce EMI.

Download more explanation about the circuit diagram of motor speed control with MAX4295 in PDF version:
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This is electronic bird chirp sound generator circuit which used to produce a sound like bird’s chirp.

The transformer is a small audio transformer, type LT700. The primary is center tapped with an impedance of 1Kohms at 1KHz . The secondary has an impedance of 8 ohms. The circuit works with 9V power supply.

How Electronic Bird Chirp Works

The inclusion of R1 and C1 give this oscillator its characteristic “chirp”. As the 100u capacitor charges via the 4.7K resistor, R1 the bias for the transistor is cut off. This causes the oscillation to stop, the capacitor discharges through the base emitter circuit of the transistor and oscillations start again. Altering these components alters the frequency of the chirp. The chirp is also voltage dependent. When the push button switch is operated the 100u capacitor is charged. When its released, the oscillation decays and the chirp becomes faster.

Components List:

Resistors
1 x 47k Ohm
1 x 4.7k Ohm

Transistors
1 x BC109 or BC337

Transformers
1 x 1K:8Ohm Audio Transformer

Capacitors
1 x 22nF Ceramic
1 x 10nF Ceramic
2 x 100uF Electrolytic

Other
1 x 9v Battery and Clip
1 x Plastic Board
1.5m of Copper Foil Tape
1 x C2222 8Ohm Speaker
1 x Momentary Push Switch

Download the sound sample of electronic bird chirp sound generator here

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Here is the circuit diagram of simple multitone alarm. This is a low cost circuit which is simple and easy to build. The main components of this circuit is based on dual op-amp MC1458 and LM 380. The two op amps inside the MC 1458 are used to produce square and triangular waves. LM 380 is used to amplify the output. The first op amp IC1a is wired as an astable multi vibrator and second op amp IC1b is wired as an integrator, to make the square wave triangle.

The two output square ans sine can be selected using switch S1 to the input of IC2 which amplifies it to drive the speaker. POT R4 can be used for tone adjustment.

Simple Multitone Alarm Notes

• IC1a and IC1b are same. So their power supply is common. Pin 6 of IC2 (inv input) has no connection.
• C1 and C2 are ceramic, C3 is electrolytic capacitor.
• A dual polarity power supply is needed here. Just need center tap transformer, bridge diode and an electrolytic capacitor. You may search the circuit in this site.

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Here is the simple and low cost mosquito repellent circuit design. The circuit serves to keep the mosquitoes out of the room or the location where the device is installed. According to certain publications, the frequency emitted by the male mosquitoes is said to be around 20??”25 kHz, and so within the realm of ultrasound. But according to others, it is in the region of 5??”7 kHz instead; frequencies that a human ear, even an elderly one, can still hear very well. Rather than spending lots of money buying such a device, which moreover generally have a fixed frequency, we’re suggesting building one yourself , especially since the circuit proposed is very simple and cheap to build.

Mosquito Repellent Works

The low cost mosquito repellent circuit uses just a single IC, a CMOS type 4047. This very multi-purpose IC can be wired in very many operating modes, including that of the multivibrator or astable used here. The operating frequency is set by the external components C1, R1, and P1. The latter makes it possible to slightly adjust the frequency, given the uncertainty that exists over the most efective value. To best reproduce the high frequencies produced by the generator, the output transducer used is a simple tweeter, but it must be a piezo one. Such a tweeter behaves in fact much like a capacitor, and so doesn’t overload the CMOS IC outputs that are incapable of supplying a substantial current.

To obtain an output signal of sufficient amplitude while being powered from a single 9 V battery. The tweeter is connected between the 4047’s Q and Q outputs. With this condition, it possible to apply complementary (antiphase) signals to the tweeter so it ‘sees’ an alternating voltage of double the supply voltage. In purely theoretical terms, this quadruples the output power available. In practice, it’s better to regard it as tripling it, but the beneft achieved by doing it this way is nonetheless very real. All that remains is for you to place the project in the middle of the patio table or beside your lounger in order to get a taste of the calm of a summer’s evening without mosquitoes bothering you acoustically or worse, biting. At any rate, that’s what we wish for you.

Source: eeweb

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