Intermittent model, when a circuit is connected to a 4,5V battery, the lamp lights up intermittently at 1 second intervals. Sold without batteries.
When connecting a 4,5 V voltage source, the base current of Transistor BC 558 flows to the 560 kΩ resistor. When the current passes through said resistance, the resistance passes and the current is carried through the 1,8 kΩ resistor to the base of Transistor BC 548/547. Thus becoming also a passage.
Now the electrolytic capacitor is charged through the base of Transistor BC 558 and this base current passes through the transistor and the lamp lights up. When the capacitor is charged, the base current of Transistor BC 558 is not sufficient to maintain it. For this reason, no current flows to Transistor BC 548/547, which also blocks it. The lamp goes out. The collector voltage rises to 4,5 V. The charge state of the capacitor is maintained momentarily and the voltage rises at the base of the BC 558 transistor to 7,4 V. Then the capacitor is discharged through the 560 kΩ resistor. The voltage at the base of Transistor BC 558 drops to 3,8 V. The circuit is then restarted.
|Construction time:||2 h.|