LED Control

tangwei8802429

LED Control [Copy link]

 

Input current 0-20MA; LED maximum current is 100MA; is this design feasible?

maychang

When the base current is too large, the LED or 8050 may be burned. C3 is unnecessary. This circuit uses 12V voltage, which is a bit wasteful.

tangwei8802429

maychang posted on 2018-9-19 21:28 When the base current is too large, the LED or 8050 may be burned. C3 is unnecessary. This circuit uses 12V voltage, which is a bit wasteful.

The base is controlled within the maximum range of the LED; if you want to limit the current, you need to get a large package resistor, but I only have 0805; C3 is to filter out external interference, and this LED is relatively close to the interference source.

maychang

tangwei8802429 posted on 2018-9-19 21:47 For the base, control it within the maximum range of the LED; if you want to limit the current, you need a large package resistor, but I only have 0805; C3 is to filter out external interference...

Is the interference so large that it can be seen from the LED light? Does the LED flicker when it is interfered with?

tangwei8802429

maychang posted on 2018-9-19 22:17 Is the interference so great that it can be seen from the LED light? Does the LED flicker when it is interfered with?

Yes, the LED will flicker.

bqgup

The voltage of 12V on the collector is a bit high, 5V is enough.

damiaa

Let's connect a resistor in series with the LED. 560 ohms?

topwon

Assuming the circuit works as expected, when the maximum current flowing through the LED is 100mA, the entire 12V loop will generate a power consumption of 12Vx0.1A=1.2W. Which device will bear this power consumption?

仙猫

You must check the LED manual first, otherwise there is no discussion.

maychang

Xianmao posted on 2018-9-22 14:44 You must check the LED manual first, otherwise there is nothing to discuss.

The first post by the OP only drew one LED. If there are several LEDs connected in series (three or four), it is necessary to discuss it in detail. If it is indeed one LED, then it is certain that the 12V power supply voltage is too high.

qwqwqw2088

The maximum current of LED is 100MA. What kind of LED is it? Ordinary LEDs will not have such a large current.

仙猫

maychang posted on 2018-9-22 20:28 The first post by the original poster only drew one LED. If it is a series of LEDs (three or four), it is necessary to discuss it in detail. If it is indeed one LED, then the 12V power supply...

I think it may be a simplified "LED module" with a constant current circuit built in. Many people are not used to revealing all the conditions first. They have to squeeze the toothpaste repeatedly before the true face of Mount Lu is gradually revealed. After crossing the Chishui River four times, they can find the direction of discussion.

15818739085

A current limiting resistor should be added to the collector of the transistor