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Audio Lm 3909 IC conduction tester Circuit Diagram

This tiny conductivity tester works with LM 3909. The tester makes a beeping sound if the resistance between the test probes between 0 and 100 O lies. Due to the volume of the beep, the resistance between the test probes can be determined. Audio Lm 3909 IC-conduction tester Circuit Diagram Parts List R1 = 1 k C1 = 10 uF C2 = 100 nF LS = Loudspeaker 12 to 16 Ω IC1 = LM 3909

SOUND DIRECTION AND LOCALISATION WITH PIC16F876A

Detecting Sound Students often want to use ‘sound’ as an input within electronic projects. Unfortunately sound is not as easy to use as light and temperature, as there is not an instant ‘single component’ solution, as is the case with, for example, an LDR for light or a thermistor for temperature. The main problems with detecting sound are: 1) electret microphone inserts are low cost, but only produce a very small signal, which requires amplification 2) the background noise level can vary considerably, and so some form of calibration is required 3) some noises, such as a hand-clap, are very quick and so can be ‘missed’ with some electronic circuits (e.g. when using a microcontroller) Fortunately these problems can all be overcome at low-cost, by using an electret microphone with three common transistors. The circuit shown in Figure 1 will produce an analogue signal between 0 and 3V that can be detected, for instance, with the analogue input pin of a PIC microcontroller (e.g. 16F876). T

ESR Low Resistance Test Meter

As electrolytic capacitors age, their internal resistance, also known as "equivalent series resistance" (ESR), gradually increases. This can eventually lead to equipment failure. Using this design, you can measure the ESR of suspect capacitors as well as other small resistances. Basically, the circuit generates a low-voltage 100kHz test signal, which is applied to the capacitor via a pair of probes. An op amp then amplifies the voltage dropped across the capacitor’s series resistance and this can be displayed on a standard multimeter. In more detail, inverter IC1d is configured as a 200kHz oscillator. Its output drives a 4027 J-K flipflop, which divides the oscillator signal in half to ensure an equal mark/space ratio. Two elements of a 4066 quad bilateral switch (IC3c & IC3d) are alternately switched on by the complementary outputs of the J-K flipflop. One switch input (pin 11) is connected to +5V, whereas the other (pin 8) is connected to -5V. The outputs (pins 9 &

500W Inverter 12VDC to 220VAC

Attention: This Circuit is using high voltage that is lethal. Please take appropriate precautions This circuit you can convert the 12VDC into 220VAC. The 4047 IC is use to generate the square wave of 50hz. Circuit diagram How to calculate transformer rating The basic formula is P=VI and between input output of the transformer we have Power input = Power output. For example if we want a 220W output at 220V then we need 1A at the output. Then at the input we must have at least 18.3A at 12V because: 12V*18.3A = 220V*1A, when P1 is 12V*18.3A and P2 is 220V*1A. So if you have to wind the step up transformer 12V to 220v but input winding must be capable to bear 20A. For this project to produce 220VAC with 500W, we find. Output power is P2 = Output voltage x output current Output current = 500W/220V = +- 2.272A most importance is primary current P1 = 12V x current 500W = 12V x current (I1)

White LED Lamp

Nowadays you can buy white LEDs, which emit quite a bit of light. They are so bright that you shouldn’t look directly at them. They are still expensive, but that is bound to change. You can make a very good solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of around 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors. The converter shown here generates a voltage that is high enough to allow ten LEDs to be connected in series. In addition, this converter supplies a constant current instead of a constant voltage. A resistor in series with the LEDs produces a voltage drop that depends on the current through the LEDs. This voltage is compared inside the IC to a 1.25-V reference value, and the current is held constant at 18.4 mA (1.25 V ÷ 68 Ω). The IC used here is one of a series of National Semiconductor ‘sim

Simple Water Alarm Circuit Schematic

Simple Water Alarm Circuit Schematic .The LM1830 fluid detector IC from National Semiconduc tor is designed to be able to detect the presence of fluids using a probe. This chip requires a relatively high supply voltage and is not the most frugal power consumer. It is also quite specialised so unless you are buying in bulk the one-off price is not cheap. An alternative circuit show n her e uses a standard CMOS IC type 74HC14. It has the advantage of operating with a 3 V supply and consumes less than 1 µA when the alarm is not sounding, this makes it ideal for use with batteries. Water Alarm Schematic Circuit Diagram The 74HC14 has six inverters with hysteresis on their input switching thresholds. A capacitor (C1) and a feedback resistor (R1) is all that’s necessary to make an inverter into a square wave signal generator. In the water alarm circuit the feedback resistor consists of R1 and the water sensor in series. R1 prevents any possibility of short-circuit between the inverter’s