Classic Alarm Circuit Employs Class-C Aamplifier for More Power

Picture of Assembled Alarm Circuit

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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Classic Two Transistor Alarm

Assemble Alarm Circuit

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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Simplest Relay Flasher Circuit with Better Stability

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 Using Two Relays

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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Digital Control for Laboratory Power Supply Using Arduino

Figure 1. Arduino Duemilanove Board for Power Supply’s Digital Control Digital System for Display and Control As the second part of the first article Adjustable 1-30V Laboratory Power Supply, the digital control and display for our power supply will be presented here. The microcontroller used in the circuit is ATMEGA 328, a member of Atmel’s AVR microcontroller family. We use […]

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Adjustable 1-30V Laboratory Power Supply Uses Switching and Digital Control Technology

Figure 1. Assembled Hamuro Programmable 1-30V Laboratory Power Supply Laboratory Power Supply Requirement Power supply for electronic circuit experiments need some special features. Ideally we need a precise, stable, reliable, and easy voltage adjustment power supply for working convenience. Being precise means that our power supply should give a voltage as close as possible to the desired value. A stable […]

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Variable Dummy Load for Power Supply Testing

Figure 1. Assembled Variable Dummy Load To test real capacity of a power supply, we need a load with variable current consumption. If we have high power variable resistor such as tapped wire-wound resistor, we can directly connect this resistor and make some measurement. Unfortunately, this kind of high power resistor is expensive and not so flexible getting wide adjustment […]

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Direct Reading Inductance Meter Employs Triangle Wave Generator

Figure 1.  Assembled Hamuro Inductance Meter Circuit Inductance and The Measurement Unit Inductance is a property of electric conductor, and it expresses the characteristic of generating electromotive force or voltage when the amount electric current changes inside it. It looks like a concept of inertia of mass in the mechanical domain when it generate force if the speed of its […]

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