Analog Temperature Controller Circuit for Soldering Station

Temperature Controlled Soldering Station With temperature control, we can take some benefits in soldering: lower cost for electric power, safer operation of soldering critical components from excessive heat, and longer life for the soldering tip. We can save the electricity power consumption up to 50% of the uncontrolled one. A high quality soldering tip, which can be expensive enough, often […]

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Far Field Noise Cancelling Microphone Pre-Amp Employs Standard Op-Amp

The microphone pre-amplifier circuit described here make the microphone sensitive to a sound come from very close source, and insensitive to any sound coming from far sources. This works even when the far sound is very loud. The main application of this circuit is in telecommunication system like in mobile phones, where the microphone should pick a clear speech even […]

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Music Controlled Disco Light Circuit with Automatic Level Control

Introduction to Automatic Disco Light Control Simple audio or music controlled disco light uses comparator to sense the beat of a music signal, but this comparator has a reference point that should be calibrated according to the music signal volume. It’s easy if we have a light jockey to take the duty of controlling all the lighting, but it’s not […]

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Ressettable Electronic Fuse (Circuit Breaker) Circuit for Securing General Power Supply

Electronic Fuse Fuse or circuit breaker is useful to protect electronic circuit, especially the power supply. A short circuit or overload might damage the power supply if the connection between the power supply and the load  is not immediately disconnected. When we use conventional fuse, we must replace the blown fuse with the new one after fixing the failure which […]

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Electronic Relay Circuit Breaker Protects Boost Converter from Short Circuit and Overload

Boost Converter and Its Unprotected Nature Boost converter topology, where an inductor is alternately shorted to ground by a switching transistor in some portion of the cycle and connected in series with the load in other portion of the cycle, is inherently unprotected from load failures such as short circuit and overload (look at the figure 1 of  the reference […]

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High Side Current Sensing Using Transistor for Current Limiting Control

High Side Current Sensing Circuit Diagram

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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Modular Fastest Quiz Controller Circuit Using Relays

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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More Complex Chasing Light Controller Using Relays

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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Small Audio Power Amplifier Using Op-Amp and Two Transistors

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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Small Audio Power Amplifier Using 3 Transistors

Amplifier Circuit

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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Chasing Lights Controller Circuit Using Relays

Chasing Light Controller Using Relays

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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Continuous Frequency Sweeping Alarm Circuit for Ambulance or Police Siren

Assembled Alarm Circuit

Sweeping out the frequency of an alarm that produce continuous spectrum has some benefits. First, it improve the alertness of the signal since people normally get alerted on the perception of “change”, and it works for almost any signal (audio, visual, thermal, etc.). Second, sweeping the frequency makes sure that  all people will get their sensitive spectrum covered. With these […]

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