![4 LED voltage indicator circuits-[Edit]](http://www.eleccircuit.com/wp-content/uploads/2012/10/very-simple-voltage-level-indicator-666x333.jpg)
This is four circuits of LED voltage indicator are simple and easy to builds for check voltage battery and others, use as zener,transistor,LM339 and more
Category: Meters & Detectors
Include: Volt meters :: Sound level meter :: Analog vu meter :: Soil moisture meter :: Digital meter circuit diagram :: Temperature measurements :: Electronic measurement tools :: Frequency meters :: Best battery tester :: Transistor tester project
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This is a simple Solar plant watering alarm circuit. It will sound alarms when the soil is dry. The trees have died. It the solar sell is 6V DC power supply. Thus saving convenience and does not require batteries.No noise at night. How the circuit works As circuit diagram in Figure 1 Figure 1 the circuit diagram of the Solar plant watering alarm. Hand draw use AAx3 batteries 4.5V The main principle is that when the soil is dry, with high resistance. However, when the soil is wet with minimal resistance. Usually the wet soil will have resistance is about …
This is a simple temperature to voltage converter circuit or an Electronic thermometer circuit there. Which will operate in a temperature range of 0 to 24 degrees Celsius (32 to 75 degrees Fahrenheit). The output rate of 500mV per degree Celsius. Which can be read by a normal voltmeter. To make it easier to find devices thus Temperature sensors of this circuit. So use a coefficient thermistor relatively constant and not linear. However, the temperature range of 0-24 degrees Celsius. This is enough to use a thermometer kind of normal. The IC1 is op-amp as the difference amplifier. There are …
This is high temperature fire alarm circuit, when the temperature rise exceeds the limit, it will sound the siren rang out. It is easy to use with transistor circuit to detects heat. Then, a loud noise of the sirens with IC packages. How it works We uses the combination between Q1 (BC109), which is silicon NPN transistor and Q2 (AC188) which is PNP germanium transistor To detect heat in case of fire. Then, the siren will sound warning beeps. The collector lead of Q1 is connected with Base lead of Q2, while the collector lead of Q2 is connected with …
High performance LM3914/LM3915 VU meter circuit projects that widely popular can display with 20 LEDs on stereo or mono with 10 LEDs for all audio system.