Adjustable Frequency Flip-Flop Circuit Using Inverter Gate

This flip-flop circuit uses one potentiometer and one capacitor as the frequency determining components. The assembled circuit is shown in the Figure 1, and the schematic diagram of the circuit is shown in the Figure 2. The circuit consists of one integrated circuit of inverter gates (4069 CMOS or  74C04), one electrolytic capacitor, two resistors, two LEDs, and one potentiometer. […]

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High Voltage 220V AC Lamp Flasher Using 555 IC

Similar with previous high voltage  flip-flop circuit, this circuit controls high voltage (powerline) bulbs (220V AC). Instead of using transistors, this circuit uses NE555 integrated circuit, a very popular chip for timer or oscillator application. The required low voltage supply for 555 IC is provided by direct converter, made up by D1, R1, DZ1, and C1. This low voltage is […]

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High Voltage Flip-Flop With SCR and Low Voltage Components

With only few components, we can use resistors, diodes, and capacitor, we can convert line voltage (220VAC)  directly to low DC voltage (10 VDC). This low voltage powers the low voltage flip-flop standard circuit, but this circuit is then used to drive high voltage SCR. This simple high voltage flip-flop circuit can be used to control alarm lamps, bell, or […]

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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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Simple Running LED / LED Chaser Circuit Using 3 Transistors

Running LED CIrcuit Diagram

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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Classic Flip-Flop Lamps Circuit and How It Works

Flip-Flop Circuit Diagram

Introduction When I learned about electronics in the past, trying to understand how circuit works by reading theories and practicing by building the circuit, the first one excited me was the  flip-flop lamp circuit. The invention of this circuit might be rooted back to 1918, when William Eccles and F. W. Jordan build the first flip-flop circuit using vacuum  tube, […]

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