Led circuits

Multi-color LED driver

Multi-color LED driver

Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can light up as independent of each other. There are only two colors that can produce this dual LED. ..

Static charge-electricity detector

Static charge-electricity detector

The detector will sense static charges and free ions in the air. It can be used to indicate the presence of ion emission, high voltage, static electricity, and electrostatic fields. The ground can be an earth ground or a touching metal by your hand. the meter is 100uA range. and R3 potentiometer is by controlling the sensitivity of the detector...

Car Voltmeter Circuit

Car Voltmeter Circuit

This screen uses ten LEDs to display a voltage range of 10.5 to 15 volts. Each LED represents a step 0.5wvolt tension. The heart of the circuit is the 3914 points LM / bar display driver. Trimming potentiometer R5 is adjusted so that 7.5 volts is applied to the upper side of the bulkhead. D2 resistor R7 and diode D5 to tighten the voltage applied to the LED 3 volts. A lowpass filter consisting of L1 and C2 guards against voltage spikes. The diode D1 is used to protect against reverse voltage where the voltmeter is connected backwards. ..

LED Chaser

LED Chaser

General There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V. This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power. Since most of the waste is eliminated, the cells last a long time...

Detection for trains on model railway

Detection for trains on model railway

This light valve can be used for example to detect trains on model railway or a lap counter at the close racing. D3 receives a constant stream of power built around T1. When the light beam from D3 to T3 is not interrupted, led T3 and T2 is the basis of practically grounded. T2 not conduct and the LED is not lit. When the beam is interrupted, spert T3 and T2 conducts and the LED will light. Of course listen to other things like LED control between plus and the collector of T2. Please note the maximum load of 100 mA. The supply voltage may be between 4.5 and 12 volts...

Constant LED power circuit

Constant LED power circuit

An LED is usually a series resistor needed to ensure that the LED does not get too much power. The disadvantage of such resistance is that the current through the LED and thus the brightness changes as the voltage changes. This circuit prevents, through independent of voltage, constant current through the LED control. The circuit uses two transistors and two resistors. The circuit can be connected to voltages from 5 to 24 V...

LED Battery indicator

LED Battery indicator

This battery allows the indicator to the car battery voltage monitor. The indicator has four LEDs which indicate power. The more LEDs, the higher the voltage. The last LED is a flashing LED. It comes on when the accuspaning limit of about 15 V limit. This is a sign that something is wrong with the alternator or voltage regulator. The other LEDs light up in 9 V (D5: bad battery), 11 V (D7: battery doubtful) and 13 V (D9: battery ok). Build the circuit and verify the above activation points. If the measured values ??much different from the above, try other Zener diodes. Of 300 mW Zener are sufficient for the circuit...

Fuse tester with LEDs

Fuse tester with LEDs

This indicator shows through a dual-LED see if a fuse is intact. The module is designed for 230 V AC. The green LED illuminates when the fuse is still good, the red lights when the fuse is broken. Perhaps the circuit to adjust for other voltages by changing the value of R1...

Transistor Tester with LEDs

Transistor Tester with LEDs

This transistor has only one IC tester and can test all types of transistors. With two LEDs indicating the type of the transistor is NPN or PNP. The circuit uses a CMOS 4049 IC. The test transistor to terminals "B" "C" and "E" attached. Then when the power is turned on, a transistor with a good LED flash. Both LEDs flashing lights or not, the transistor is broken. ..

Transistor tester schematic

Transistor tester schematic

This is a convenient design for a transistor tester. The advantage of this circuit is that transistors can be tested without actually doing the circuit soldering. The tortester uses two ICs: an NE 555 timer and a CMOS IC 4027. In 4027 there are two flip-flops. The timer generates a square wave of about 12 Hz. IC2 through the square wave then used to test the transistor. ..

Thyristor / TRIAC Tester

Thyristor / TRIAC Tester

This is a simple but effective and thyristor TRIAC Tester. Operation at a good thyristor / triac: LED lights when SW3 is pressed. LED turns off when SW2 is pressed. If this occurs, the thyristor / triac OK. Tip: Hirschmann clips for the tested thyristor / triac connecting, including this quotation terminals. The supply voltage is 9V, with a minimum current of 400mA. ..

Phone Busy Indicator schematic

Phone Busy Indicator schematic

This indicator shows whether the phone is busy or not. When the line is busy, LED D6 off. The line voltage at points A and B attached. By the rectifier bridge behind the connection, the polarity does not matter. The voltage of 60 V is the voltage divider. The voltage at the voltage divider to the negative mass (capacitor and zener diode are not incorrectly signed). When the line is not busy, the line is approximately 60 V. ..

Wet soil tester with LED

Wet soil tester with LED

This is a very simple circuit that can be used to test whether a pot is dry or not. When the two probes are inserted in wet soil, then the resistance between the sensors are low. The base of T1 will therefore be more negative and the LED is not lit. However, when the soil is dry, its resistance will be high and will base more positive. ..

LED tester circuit

LED tester circuit

This ledtester uses as a power switched opamp. The control range is about 0-30mA. Thus, all test and standard LEDs, the voltage across the LED to read. The power supply is an example labvoeding at least 15V, 12V adapter if you're a U2 expires. Then put a jumper between pins 1 and 3 and use a 10uF electrolytic capacitor for C1. The LM358 is only half used the other half to the mass shut down. ..

Conductivity Tester circuit

Conductivity Tester circuit

This little guide for every electronics tester would actually have to lie in the toolbox. You can have components such as resistors, capacitors, diodes, etc. of testing. T1 and T2 form a Darlington. Therefore only need a small base current to run and the LED is already lit. The tester is suitable for up to 2 M? resistors. The tester is also suitable for capacitors. When a capacitor is connected to the leads, the LED, depending on capacity, light briefly and then to extinguish. ..