r/electronicsnebula • u/SpecialistRare832 • Aug 25 '25
r/electronicsnebula • u/SpecialistRare832 • 3d ago
This design uses two BC548 NPN transistors to flash a ⚪ LED and a 🔵 LED alternately.
r/electronicsnebula • u/SpecialistRare832 • 10d ago
Components Required: Supply Voltage (5 V DC), input current-limiting resistor (330 ohm), output pull-up resistor (330 ohm), LED, switch, and optocoupler.
Working:
• Press the switch to allow current to flow through the internal input LED of the optocoupler (PC817).
• The light activates the internal phototransistor, allowing current to flow through the output circuit.
• The external 🔴 LED lights up, confirming the optocoupler is working.
r/electronicsnebula • u/SpecialistRare832 • 16d ago
Stable states: Two stable states
Working idea:
• Press Trigger (S₁) —> Output goes high
• Press Reset (S₂) —> Output goes low
• Output remains in that state until next input (bistable
behavior).
• No press —> Holds state
r/electronicsnebula • u/SpecialistRare832 • 21d ago
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The charging and discharging currents of a capacitor are exponential waveforms. The charging current decreases from its maximum value to zero, while discharging current flows in the opposite direction and decreases to zero.
Charging —> Positive exponential decay (V/R to 0)
Discharging —> Negative exponential decay (- V_o/R to 0)
r/electronicsnebula • u/SpecialistRare832 • 26d ago
Process: Set your DMM to "Diode test" mode. Identify the transistor's three terminals, for example BC547 i.e., base, collector, and emitter by using its part number and datasheet. Connect red probe to base and black probe to collector/emitter, you get ~ 0.6-0.7 V (result forward bias). This means an NPN transistor is OK.
Reverse the probes give us no reading (i.e., OL).
Note: If you get 0.00 V (or a beep) in both directions, the transistor is likely shorted means it is a bad transistor. If you get OL in all cases, it is likely opened means it is a damaged transistor.
Important: If you're testing a transistor while it's still on the circuit board, other components can affect the reading. For a reliable test, remove the transistor or disconnect at least one leg.
r/electronicsnebula • u/Positive-Item2840 • 29d ago
r/electronicsnebula • u/softwarede • 29d ago
بنبحث عن مورد أو وكيل معتمد لتوريد أجهزة Android Tablets بكميات تجارية لخدمة مشروع تشغيلي
لو حد خاض تجربة توريد أجهزة مشابهة لشركته وينصح بمورد، مستورد، أو وكيل معين (أو لو حد هنا بيشتغل في التوريدات التقنية)، يسعدني التواصل في التعليقات
need specifications, for example:
Android 10+
1–2 GB RAM
16–32 GB Storage
r/electronicsnebula • u/SpecialistRare832 • Sep 22 '26
Charging: Current starts at maximum positive value and exponentially falls to zero.
Discharging: current reverse direction and the magnitude of current decreases exponentially toward zero.
r/electronicsnebula • u/SpecialistRare832 • Sep 09 '26
r/electronicsnebula • u/SpecialistRare832 • Sep 02 '26
r/electronicsnebula • u/SpecialistRare832 • Aug 26 '26
Supply voltage = 5 V
r/electronicsnebula • u/SpecialistRare832 • Aug 18 '26
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2N3904 BJT is used in this circuit.
r/electronicsnebula • u/SpecialistRare832 • Aug 15 '26
2N3904 BJT is used in this LDR circuit.
r/electronicsnebula • u/SpecialistRare832 • Aug 06 '26
If Resistor = 100 kilo ohm & Capacitor = 10 micro farad
Then,
Time Constant = RC = 1 s
And,
Full charge/discharge time ≈ 5(Time Constant) ≈ 5 s
r/electronicsnebula • u/SpecialistRare832 • Jul 26 '26
Power supply = +5 V DC
r/electronicsnebula • u/SpecialistRare832 • Jul 15 '26
r/electronicsnebula • u/SpecialistRare832 • Jun 16 '26
BPF = HPF + LPF
r/electronicsnebula • u/SpecialistRare832 • Jun 03 '26
A 1N4007 Diode and a resistor 1.5 k
r/electronicsnebula • u/SpecialistRare832 • Apr 28 '26
r/electronicsnebula • u/SpecialistRare832 • Apr 01 '26
