I suspect like many here just now I'm in lock down and in my case I'm not even supposed to leave the house. I have built Banggood kits before and apart from the lack of any instruction etc they have generally been OK and good value for money. This one is called an IR Detector and I bought it some time ago. Here's a link to Banggood's information on it which for these kits is quite good and includes a circuit diagram.
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https://m.banggood.com/DIY-IR-Infrared-Sensor-Switch-Kits-Infrared-Proximity-Switch-Circuit-Board-Electronic-Training-Kits-p-1300901.html?rmmds=newArrivals#popupStatedetail
The kit contains 3 LEDs (one IR transmit, one IR receiver and an ordinary red LED). There are 5 diodes. Two of these are 1N4007 and the other 3 are said to be zener diodes. This is where my problem lies as one of these is missing from the kit. They are shown on the circuit diagram as 4148 though the symbol for a zener diode is not used. The diodes themselves are marked st4148. I can only find a reference to a 1N4148 on the net. This is not a zener diode. I downloaded a data sheet for these which gives the package size which seems to be the same as the 4148s in the kit though I realise this probably doesn't mean much. I have some 1N4148s. I also have some zeners i.e. BZX85 3.6V, BZX85 5.6V (not sure why these have the same number but different voltages), BZX61 7.5V and BZX79 9.1V. I I'm hoping the some one more knowledgeable than me could have a look at this and perhaps suggest a replacement for the missing diode from the ones I have. I've attached the circuit diagram for convenience.
Regards,
Ken.