Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

i am working on simple infrared circuit

Not open for further replies.


Member level 2
Jan 28, 2011
Reaction score
Trophy points
Lahore, Pakistan
Activity points
i am using simple infrared transmitter and reciever leds.....
i transmit a dc signal cia infrared trans. by biasing it at 5v (with a resistor to gnd)....and same way biasing the reciever but the reciever gives continously full voltage drop...i.e it is open circuited all the time
I want it to become short circuitd normally and then become open when the infrared signal doesn`t fall on it. If anyone has a simple circuit of it the plz let me know

you need to say what type of receiver. Most are high impedance, you will need a circuit around them.
google "infra-red proximity detectors" should find you a bunch.
I have personally done one using IR 3-terminal receiver (as found in TV's for remote) and IR LED pulsed at 30-40kHz.
These especially don't work with a "DC" level of infra-red so they can ignore ambient infra-red

This is the ckt i am trying to implement ........whats the problem with this??


  • ckt.bmp
    837.3 KB · Views: 76

For testing purposes keep the receiver diode in the dark.

See if you can use a lens to focus more of the beam on the receiver. (I know, not easy with infrared. Temporarily substitute a visible led instead.)

Vary the inline resistance. You want to find the maximum voltage swing for your range of dark versus lit conditions.

The diagram shows you are biasing the receiver diode so it's on all the time. You may get reduced performance in that case. Or no performance.

The diode may be the kind that produces voltage when lit. You should construct a circuit to detect this.

It may work if you add a transistor so as to obtain lo ohms in dark, and hi ohms when lit.
Last edited:

off hand I would say thats not going to work , like I said beforehand. You could try a high value for R2, say 100k
and view the voltage across the ir-receiver with a high impedance voltmeter, see if you get any variation whilst blocking the ir transmitting led.
What part number is the IR receiver ?

if u have any other purposal for this ckt then plz is also known as "RAY CUT" ckt

Not open for further replies.

Part and Inventory Search

Welcome to