Ok, the PT202C is a phototransistor, not a photoLED. At least on the datasheet that I looked at :
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This phototransistor is sensitive to visible and near IR light. The visible light you will have to filter out. But, first you must compare the wavelength sensitivity curve of the phototransistor with the wavelength emitted by your transmitter. Looks like the PT202C is most sensitive around 900 nm.
If the wavelengths are close, then you must block out the visible light to keep the phototransistor from saturating. Color slide film that has been developed but never exposed to light works well. Search the internet or see
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Often at least two pieces are required. The filter will appear opaque to the naked eye. However, put it in front of your digital camera and do the transmitter test, you will see that the IR goes right through.
To check if the photo transistor is saturating, measure the voltage at the collector. Bottom side of R5. If the voltage here is close to ground or only a volt or two, with the transmitter off, then the transistor is saturating. Use the IR filter or for testing use a dark room at night with most or all lights off. If it starts to work, then you know your problem. Some phototransistors have a black or smoke gray body. These have an IR filter built into the plastic. The original transistor may have been of that type, which could explain no mention of a light filter.
Since, the transmitted frequency is 1KHZ, you are in luck as this is in the audio range. You could take a series capacitor to block the DC and a voltage divider attenuate the signal and then feed the result into an audio amplifier. If the signal is present, you will hear the constant 1KHZ tone. (The voltage divider is either a variable resistor or two resistor in series. Try a series capacitor of around 1uF and a variable resistor of about 20K to 47K.)
Also, since this is an audio range signal, you could feed it into a PC sound card. There is some software that will sample the audio input and display it like an oscilloscope. I have never used it, but you can search the web.
Whether you use the audio ampilifier or the PC sound card, always use a blocking capacitor and some series resistance to limit the potential harm to your equipment. There is some risk to the audio amplifier or the PC. Many, many people have done this successfully without problems. However, a wrong connection could cause damage, usually people buy a cheap sound card for this method rather than using the feature built into an expensive laptop or motherboard. If an accident happens and the cheap sound card is damaged, they just throw it away and buy another one.
Finally, if you have several issues of the magazine, I would study the issues for the months following this article. If the article had any corrections, they would show up in the following months. Also, read the letters to the editor. If others built the circuit with great success, they probably wrote a letter about it. Also, if people could not get it to work, the letters column may mention this as well.