Do IR LEDs need resistors?
For example, an IR LED has a forward voltage of 1.2 volts at 20 mA forward current. Furthermore, when operating an LED from a DC voltage source higher than the LED’s forward-voltage, a series-connected (dropping) resistor needs to be utilized to prevent full source voltage from damaging the LED.
Do LEDs use transistors?
LEDs are current-driven devices. Therefore, an LED driver circuit is one that supplies sufficient current to drive them. This can be done with a simple transistor, as shown above.
Are transistors used in light switches?
Transistor switches can be used to switch and control lamps, relays or even motors. When using the bipolar transistor as a switch they must be either “fully-OFF” or “fully-ON”. Transistors that are fully “ON” are said to be in their Saturation region.
Which transistor is best as a switch and why?
Best Transistors: BJTs
- #1 NPN – 2N3904. You can find most often NPN Transistors in low-side switch circuits.
- #2 PNP – 2N3906. For high-side switch circuits, you need a PNP style BJT.
- #3 Power – TIP120.
- #4 N-Channel (Logic Level) – FQP30N06L.
How do I increase my IR range?
The IR diode will provide output power of maximum as given in spec. What people do to increase range is that they add 4-5 diodes in parallel for higher output power. This increases range.
What resistor should I use for IR LED?
The 18 ohm resistor should limit the LED current to about 80 mA – safely under its maximum rating of 100 mA. 20 or 22 ohms would reduce the current a bit more, if you want to be safer.
Does transistor have resistance?
In today’s world there are two major types of transistors, MOS and Bipolar. Both of them have ohmic resistance at their terminals since they are made of physical materials. Ohmic resistance would be a device that behavs in a way such that the current through it is directly proportional to the voltage applied across it.
Which way does a transistor go?
Transistors typically have one round side and one flat side. If the flat side is facing you, the Emitter leg is on the left, the Base leg is in the middle, and the Collector leg is on the right (note: some specialty transistors have different pin configurations than the TO-92 package described above).
How do I choose the right transistor?
In choosing a suitable switching transistor:
- The transistor’s maximum collector current must be greater than the load current.
- The transistor’s maximum current gain must be at least 5 times the load current divided by the maximum output current from the IC.
Does it matter what transistor you use?
It is important to know what type the transistor is because there is a difference in the base emitter forward bias voltage drop. For example a low power general-purpose transistor is unlikely to work well in a switching application even if it has a high ft or frequency limit.