Electronics

On-Off Switch using relay

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Here’s how industrial equipment is started and stopped using push buttons(On-Off Switch). The circuit is called a “locked-out relay.” It uses an ordinary relay and the ON switch activates the relay to close the terminals. When the switch is released, the relay remains activated and the load is powered via the contacts of the relay. […]

Electronics

Simple Battery Charger

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Here is a very simple example of a low-cost battery charger for 12 v 7Ah lead-acid batteries. As shown in the figure, diodes 1N4001 (D1) and 1N4001 (D2) form a full-wave rectifier. The rectified voltage appears across SCR1 and the battery to be charged. At low battery voltages, SCR2 is in cut-off state. SCR1 is […]

Electronics

Dark Sensor

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Dark Sensor

Dark sensor using 2 transistor BC547 When light falls on LDR, its low resistance drives the transistor T1 into conduction. This keeps transistor T2 cut-off due to low base bias. The LED does not get power as long  as ambient light falls on it. Parts list T1 and T2 – BC 547 LDR  -1 nos Resistance […]

Electronics

Electrical Appliance Protection

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Electrical Appliance Protection

This simple circuit of electrical appliance protection  is to protect your electrical appliance during irregular power supply. Normally when power goes off we forget switching off our appliances. Especially in India where power cuts are very frequent we tend to leave our appliances on. In such case there are very high chance of getting it damages […]

Electronics

LED Flasher using NE555

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LED Flasher circuit using NE555 timer IC   R1, R2, C1 and the supply voltage determine the flash rate. For a variable flash rate, replace R1 with a 1 MΩ pot in series with a 22k resistor. The purpose of R3 and R4 is to limit current through the LEDs to the maximum they can handle […]

Electronics

USB Reading Lamp

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USB reading lamp is powered using USB port. The USB port provide 5 v and 100mA which is sufficient for this circuit. Cut the one end of the USB cable and use RED(pin1) and Black(pin4) for 5v positive and negative respectively.   Parts c1,c2 – 100 mF 25 v Zener diode – 4.7v 400m R1- […]