Electronics Area – Electrical and Electronics Tutorials and Circuits
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Electrical and Electronics Tutorials and Circuits
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Diode Connected in Parallel to a Relay Coil – Relay diode
The purpose of a diode connected in parallel to a relay coil (flywheel diode or freewheeling diode) is to avoid damaging some nearby components sensitive to high voltage.
Power Failure alarm using transformer and relay
Power failure alarm using transformer and relay
This power failure alarm circuit is very simple and is very useful when used with electric ovens, a refrigeration systems or to prevent a thief from cutting off the electrical power because it immediately warns of the problem. It also serves you when the fuses have blown.
4-channel audio mixer using LM3900 IC
4 operational amplifiers, some resistors and capacitors to implement an audio mixer with a very simple design.
Resistance measurement of delicate components
There is a special way of resistance measurement when the component to be measured is very sensitive or delicate.
Door opening monitor
Door opening monitor
The circuit allows detecting the opening of one or more doors with an audible and a visual warning.
3 Auto Shut off Battery Charger circuits (12V)
Why is an auto shut off battery charger needed? The main reason to get an auto shut off battery charger is to protect the battery from overcharging and consequently reducing its useful life….
Bike Flashing LED Lights Circuit
Bike Flashing LED Lights Circuit. If you’re a cycling fan, and you like biking, night and day, this useful circuit will make you to be visible and safe
12V Auto Turn-off Battery Charger with Current Limiter
12V Auto Turn-off Battery Charger
This 12V Auto Turn-off Battery Charger with current limiter, uses only 4 transistors, will stop charging the battery when it has 14 volts between its terminals and limits the charging current to a maximum of 2 amps.
How to Measure Beta of a Transistor?
The beta (β) is a characteristic of each transistor. This feature is found in the NTE, ECG manuals, etc. These manuals have a minimum or approximate values of the real values. This means that we do not know the real value of the transistor.
How to protect multimeter’s 500mA fuse?
A very simple circuit that protect the 500mA fuse of a multimeter, due to the high frequency that these are burned.
6 LED VU meter using a single transistor (circuit)
This simple 6 LED VU meter circuit allows us to visualize the level of an audio signal. Due to its few components, it is a cheap circuit and easy to build.
Music Box Circuit Using a CD4017 and Two 555
This circuit attempts to emulate the operation of a music box. The maximum number of notes is 10, allowing us to make a simple melody.