Tag Archives: Alarm

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MAX1703 Single-Cell Boost Converter Circuit

When you design a circuit with only a single-cell battery, you will need boost-converter to provide enough voltage for most ...

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55MHz Scope Sensitivity Amplifier

Scope sensitivity amplifier is a vital front-end signal processing for every scope instruments. The function of this circuitry is simple: ...

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Two-Band Bxandall Active Tone Control

Using active circuit for tone control means that we can provide cut and boost, maintaining overall amplifying factor of original ...

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Pulse Width (PWM) Controller Circuit

A LM3900 quad operational amplifier can be used to build a pulse width (PWM) controller. The LM3900 was chosen because ...

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Small TV Modulator Using A Motorola MC1374

How can television modulator be small and simple like this? First, it uses integrated circuit, and the second, any TV ...

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Drive Safely wth Speed Alarm

At high speed, visually checking your speedometer to keep under maximum speed can be dangerous. It will be much safer if we put an audio alarm system to give a warning if the speed reach a certain threshold. To build … Continue reading

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Delayed Car Door Alarm

Opening car’s door is very simple activity, and off course it’s just a daily activity which require no special skill. Almost nothing can go wrong, but forgetting to close the door when we doing or thinking on many tasks is … Continue reading

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First-Response Monitor with SCR (Quiz Alarm)

A pair of cross-coupled SCRs can be used to build a first-response monitor circuit, as shown in the schematic diagram below.  First-response circuit is popular in quiz application where the first contestant who press the button will prevent the other … Continue reading

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Phone Incoming Call Flasher

This is a circuit of phone message flasher, an alternative way to get alarmed when there is an incoming call. When the phone rings, high line voltage will be detected by A differential amplifier with hysteresis (Q2, Q3, and Q1). … Continue reading

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