The judgment of the performance is good or bad, positive and negative resistance value measurement of light-emitting diodes multimeter R × 10k file. Normal forward resistance value (black pen then positive) about 10 ~~ 20kΩ reverse resistance is 250kΩ ~ ∞ (infinity). The higher sensitivity of the light-emitting diode, in the measurement of the forward resistance value within the tube will shimmer. Measured with a multimeter R × 1k file light-emitting diode, the reverse resistance value, it will find its positive and negative resistance value close to ∞ (infinity), this is because the light-emitting diode forward voltage drop is greater than 1.6V (higher than the multimeter R × 1k files battery voltage value of 1.5V) sake. Pick capacitor positive (black pen, red pen then capacitor negative charging a 220μF/25V electrolytic capacitor with a multimeter R × 10k file), and then charge the capacitor cathode connected to light-emitting diode anode capacitor anode connected light-emitting diode negative if light emitting diode has a very bright flash, then the light emitting diode is intact
3V DC power supply is also available, a 33Ω resistor in series in the positive power supply connected to the light emitting diode cathode connected to the negative terminal of the power supply negative electrode of the light emitting diode (see Figure 4-74), and the normal light-emitting diodes emit light. Black pen or a 1.5V battery in series with the multimeter (multimeter R × 10 or R × 100 stalls, black pen then the battery negative, is equal to the series) with the statement 1.5V battery, battery cathode connected positive light-emitting diode, the red pen then the negative of the light-emitting diode, the normal light-emitting diodes to emit light. |
