Free Electronic Circuit Design
Introduction to Current Sensing Current sensing is sometimes needed in a circuit to measure the amount of electric current flow. In signal communication for example, current sensing circuit is needed to read the measurement of remote sensor via current loop. Other common application is in the power supply circuit, when we need to limit the maximum current drawn by the […]
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Introduction Fastest quiz controller is basically a switches controller, the switches are then used to control lamps and or alarms, which are designed to make indication of who is the first contestant that push the knob first, so the host can give the question for him. Many circuits of such controller are available on many websites, but here we present […]
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Producing More Perceptible Light Movement And Lowering The Power Consumption Chasing light controller presented in our previous light controller circuit has very simple design. It control three lamp power lines to make moving light effect by turning on two lamps and turning off one lamp in sequences. Now I have designed new moving light controller circuit which turning on only […]
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Sometimes we need small power amplifier circuit while we have unused op-amp section in one of our applied chip. Instead of adding more IC (such as LM386 or similar devices), adding two small transistor and several passive components can be cheaper solution if we can employ the unused op-amp section. Using two small transistors (2N3904 and 2N3906), we can build […]
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For some simple applications such as toys, intercom, or small gadgets, there is sometimes a need for small, simple, low cost, or low voltage solution of power amplifier circuit. For this requirement, high fidelity is rarely needed. A modification of amplifier circuit from Bowden’s circuit collection is presented in our article, completed with the guidance on how to modify for […]
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Introduction to Chasing Light Running lights or chasing light is very attractive for advertisement display. A sequence of on-off at minimum three lamps gives an effect of moving lights. These three lamps then can be extended by paralleling the wire to give long bulbs chain. Modern lighting control system might have micro controller inside for complex lighting pattern, but here […]
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Running/Chasing LED Circuits on The Web Running LED circuit, or sometimes called LED Chaser circuit, has very popular implementation using 4017 integrated circuit (IC). Almost all electronic websites has the circuit in their list of schematic diagram collection, you can check this dancing light circuit for example. The circuit based on that IC, is very flexible since its speed can […]
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Introduction Classic series relay flasher circuit usually need minimum wattage for the connected load to work. Beyond the specified minimum wattage, then the flasher will not work or become unstable. Here I designed a simple solution using DPDT relay, that works for loads with any wattage. The Circuit and How It Works The circuit need one DPDT relay, two resistors […]
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Basic alarm with small transistors presented in our previous alarm circuit article is usually enough for toys, but we might need more power if we wanna use it for automotive or industrial application. If you usually see class-c amplifier application in radio frequency circuit, then we will show you how it can be applied in audio circuit as well. From […]
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A very simple alarm circuit can be built using two transistors and several passive components. We don’t know who is the inventor of this circuit, but it usually presented in many old electronics books, so let’s call it “classic”. This simple circuit implement complete function of an alarm, which is nothing more than an oscillator with high enough power to […]
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A flasher circuit with only three components (relay, capacitor, and resistor) is very popular design, which is advertised as the simplest design for relay flasher. I don’t know who is the designer of this circuit but the schematic diagram is spread on many websites. Here is one example, using 12V relay, 220Ω, and 2200uF capacitor for building 12V flasher circuit. […]
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Lamp Flasher Circuit Lamp flasher circuit is an electronic device that control a lamp to flash in periodic manner. Lamp flasher can be designed using semiconductor or other active components. Here we use two relays as the active components, plus some other passive components. Relay can be considered as an active component since it receives small power input to control […]
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