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current passing through led when switch s1 is closed
probotics

probotics

@copilot current passing through led when switch s1 is closed
1y

copilot

To determine the current passing through the LED (LED1) when the switch S1 is closed, we need to consider the circuit elements involved and the connection paths. Since the project you've described leverages a blinking circuit using an astable multivibrator configuration with two transistors (Q1 and Q2), the LED current will not be constant but rather will blink, corresponding to the switching states of the transistors.
However, for the sake of simplicity, let's calculate the approximate current through the LED when it's in the "on" state, assuming S1 is closed and thus the circuit is powered.
Assumptions:
  1. The voltage across BATT1 is 3V (as specified).
  2. The forward voltage ((V_f)) of the LED is 1.6V (as specified).
  3. The resistors in the paths of current flow to LED (R1, R2, or R3) do not directly limit current through LED1 as their impacts are part of the multivibrator's timing and switching function, not directly in series with LED1. Their roles are more complex in affecting the timing and operation of the circuit rather than merely limiting current to the LED.
  4. The astable multivibrator oscillation frequency and duty cycle could be determined by the capacitors (C1 and C2) and resistors (R1, R2, and R3) values, but for LED current calculation during "on" state, we focus on the voltage drop and source.
Simplification for LED Current Calculation:
  • When the LED is on, it is because one of the transistors (either Q1 or Q2) is conducting, directly connecting one of the LED pins to ground through the transistor's collector-emitter path, while the other pin of the LED is connected to the positive supply voltage via the closed S1.
  • The current through the LED ((I_{LED})) can be approximated by considering the voltage drop across the LED and the supply voltage when it is in the conducting state.
[I_{LED} = \frac{V_{supply} - V_f}{R_{series}}]
However, since there isn't a specified resistor in series with the LED for current limiting within the given information (assuming direct connection through transistor switching), we cannot accurately calculate without the specifics of the internal resistance or the exact operational state, including the transistor's saturation state that would affect the exact current.
In typical LED circuits, a current-limiting resistor is placed in series with the LED to prevent it from drawing excessive current. The absence of this in your description might be an oversight or handled differently in your simulation.
Important Note:
In practical circuits, always ensure there's a resistor in series with the LED to limit the current to the LED's safe operating range, typically around 10 to 20 mA for common LEDs. Without this information or a clear path for calculating the resistance affecting the LED's current, we suggest reviewing the circuit design for elements limiting the LED's current or providing more specifics for a detailed calculation.
1y
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C2
Capacitance
25u F
Manufacturer Part Number
875105359001
Q1
Manufacturer Part Number
MMBT3904
Q2
Manufacturer Part Number
MMBT3904
C1
Capacitance
25u F
Manufacturer Part Number
875105359001
R1
Resistance
1k Ω
Manufacturer Part Number
RMCF0805FT1K00
S1
Switch
R2
Resistance
47k Ω
Manufacturer Part Number
RMCF0805JT47K0
R3
Resistance
47k Ω
Manufacturer Part Number
RMCF0805JT47K0
LED1
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Blinking LED Circuit Simulation

Blinking LED Circuit Simulation
Description

Created
Last updated by vasyl
Forked from
natarius/example-simulation-of-astable-multivibrator-circuit
1 Contributor(s)
vasyl

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