This Homemade Power supply is useful for the Electronics hobbyists and service persons to test and troubleshoot the circuits. It gives six stage well regulated output power with a current of 800 mA. Its construction is “Open type” as it is home made. You can make it like a professional power supply by fixing inside a box with connectors for tapping the output.
Continue reading “Home Made Power Supply. Home Utility Circuit 27”
Here is a simple Portable Power Bank that finds many uses. It can be used as a Portable Mobile Charger or it can be used for powering the bread board projects and so many applications that requires 5V Regulated DC. Let us make it.
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Presenting here three circuits to make efficient Battery chargers. The 12 volt Lead Acid Car battery requires high current for fast charging. If we provide high current, the battery will charge within 1-2 hours fully. Usually a Lead Acid battery takes high current initially, which drops to 500 mA or less after 10-20 minutes. As a rule, it is advisable to charge the battery with a current that is 10 times lesser than the battery capacity. The Car battery is 32 Amps or 45 Amps so it requires 3.2 Ampere and 4.5 Ampere current respectively. So the charger should provide 14 volts with a current of 5 Amperes.
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The handy low cost 433 MHz Transmitter and Receiver pair is now widely used in Arduino based circuits. But one of the serious problems with the Receiver is its inherent property of accepting lot of noise from the background. This gives erratic output data which causes error reading. If the output is connected to an audio amplifier, hissing sound appears in the speaker when the receiver is in standby without receiving the signals from the transmitter. So careful designing of the power supply and a Glitch removing circuit will considerably reduce the noise from the data out of Receiver (Rx).
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One simple way to protect circuits from over voltage is the use of a Shunt Regulator IC TL431 to switch off the load if the voltage increases above the preset level. In unregulated power supply, if the voltage in the primary of the step down transformer increases, a corresponding increase in voltage will appears in the secondary also. This may seriously affect the circuit, if it uses voltage sensitive semiconductors.TL431 is an adjustable precision Zener shut regulator and its output voltage can be set between 2.5 volts to 36 volts using a voltage divider. It can functions like a Zener diode but with precision.
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