How to simulate infrared receiver in Multisim 9

multisim 9

i'm working on Infrared Remote Control Fan Regulator. I designed the receiver with Phototransistor but i can't simulate it in Multisim 9 and there is no IR receiver IC like 1738 on the component database. It gives error each time i simulate the circuit.

Please any suggestion on what to do because i would want to simulate and make tune the circuit very well

phototransistor multisim

Here is how I would approach it.

1. Connect a scope across the photo-transistor and capture its response to the IR transmitter.

2. Create a voltage source in your simulation and use piece-wise linear transitions to approximate the voltage and timings you saw on the scope. Remember to include a series resistance equal to the output impedance of the photo-transistor.

3. You can also add additional voltage sources in series at fixed sinewave frequencies. These represent the noise signals that your receiver must reject.

Also, is the IR base-band or modulated on a carrier? If it is carrier modulated, you can figure out the limits of the sideband signals, and tune your circuit by sweeping the frequency through this range.

tsop1738 spice

Thank you Banjo. The Phototransistor does not respond to the IR transmitter, it just gives error message. If you want i can capture the rror message on the screen and post it here. Meanwhile, the transmitter is built around a astable multivibrator at the frequency of approx 38KHz using an IR LED.

I had tried to use an IR sensor (TSOP1738) for the receiver but is not contained in the component database of Multisim 9. Can it be added? If yes, how?

I will appreciate any suggestion on how to solve this problem

multisim infrared

When I mentioned capturing the signal on a scope, I was referring to the actual hardware, not the simulation circuit. I was suggesting using real data to model the input in SPICE.

I am familar with SPICE simulation, but not Multisim in particular. Therefore, I do not know how to add a component to their database. First step would be to see if the manufacturer has a SPICE model available. Being that it has an IR input, I kind of doubt it.

If the goal is to tune the IR receiver, then I would suggest replacing the photo-transistor with an ac voltage source and a series resistor and doing an ac sweep. That will tell you the frequency response of your receiver.

Again, I do not have direct experience with Multisim, however, the usual reason for this type of simulation fail is that the simulator could not find a stable bias point. Look through the settings for anything that increases the number of iterations for the bias point. See if you can preset any of the node voltages to reasonable values to help it find an operating point.

If you have the astable multivibrator in SPICE, you can just couple the transmitter and receiver together with a small capacitor. This will by-pass the IR link, but at least show the response of the rest of the circuit. If the reset of the circuit works with the IR link by-passed, and the actual circuit does not, then the problem must be in the IR stages. Transmit IR problems can be diagnosed by looking at the current through the IR diode. The IR light will be analogous to this current. Receive IR problems are often external events like sunlight or another light source swamping out the sensor. Try running the actual hardware in a dim to dark room. Does it work better?