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4 votes

What type of regulator to use for LEDs in a scale model vehicle?

I'll assume you're using a suitable power supply like 5V or 12V. The simple way is to use a current-limiting resistor. You can determine the resistor value in three steps: determine your required ...
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2 votes
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Identify number of strings in Philips 14.5W LED PCB

Is it possible by just looking at the attached image whether the LEDs are in a single series circuit, or whether they're configured in series/parallel? Follow the tracks and you'll see that two ...
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1 vote

How do you cascade two 7-segment decoder ICs together?

The 74xx47 chip can be configured (with /RBI low) to leave the output blank instead of displaying a zero digit, so that the two-digit output is " 0" instead of "00". With the "...
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1 vote

Efficiently limit current to LED without power loss

From what I understand of this circuit is that when the voltage of R3 exceeds the voltage that is required to turn on Q1, the gate of Q2 will be pulled to GND and the Q2 will be turned off. Hence, ...
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1 vote

Ring oscillator not oscillating

The 1Meg resistors are so high that the current gain of a typical BJT won't give a net gain around the loop of over unity, so no oscillation. MOSFETs don't have a problem with this high resistance. To ...
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