# 555 Timer for 10 LEDs

#### Khisraw

Joined Nov 14, 2020
56
Hi,
I am using 555 Timer on astable mode to generate a 38Khz frequency for an IR LED. It might be a simple question but does anyone know how LEDs I can drive (All at the same time) with a single 555 Timer?

#### dl324

Joined Mar 30, 2015
17,009
Some combination of parallel or series+parallel.

What current do you want for each LED? What voltage are you operating the timer at? What is the forward voltage of the LEDs?

A bipolar 555 timer can sink/source about 200mA. If you need more, you can have the timer drive a MOSFET.

#### Khisraw

Joined Nov 14, 2020
56
Some combination of parallel or series+parallel.

What current do you want for each LED? What voltage are you operating the timer at? What is the forward voltage of the LEDs?

A bipolar 555 timer can sink/source about 200mA. If you need more, you can have the timer drive a MOSFET.
All in parallel. A single LED will need a maximum forward voltage of 2V at 50mA

#### dl324

Joined Mar 30, 2015
17,009
All in parallel. A single LED will need a maximum forward voltage of 2V at 50mA
What voltage is the timer operating at? You'll waste less power as heat if you can do series+parallel.

With a 2V forward voltage, operating 2 in series with a 5V supply would give a current limiting resistor of 20 ohms.

What is the maximum continuous and peak current spec for the LEDs?

#### Ian0

Joined Aug 7, 2020
10,054
If you are not using pin 7 (discharge) as part of the timing circuit then it can drive some LEDs as well as pin 3, until you reach the maximum for the negative power supply pin.

#### Wolframore

Joined Jan 21, 2019
2,610
Most of the IR LEDs I’ve used have much higher current rating than similar red LEDs. I’ve seen specs around 100 mA or more (continuous)... why not just use the output of the 555 to a transistor which can sink more current.

#### bertus

Joined Apr 5, 2008
22,290
Hello,

What will be the purpose of the circuit?
If it is an IR jammer, we can not allow the circuit:

Bertus