Unfortunately there’s a defect in the first batch of USB IR Toys. The infrared LED is backwards and does not emit properly. Ytsirk caught this defect and documented the issue in the forum.We’re really sorry about this bug, and we’ve done our best to track it and identify the cause.
We used a Cadsoft Eagle IR LED footprint in the USB IR Toy, specifically the SFH-482 from the default LED part library. The IR Toy design doesn’t require the SFH-482, almost any IR LED will work, but that is the package we found first. The silkscreen for the Cadsoft part has a tab on the anode (+ side) of the LED (bottom right image). The SFH-482, according to the datasheet, actually has the tab on the cathode side (top image). We used an IR LED on our prototype that looks like a normal LED without a tab, so we didn’t see the problem with the silk. We should have caught this and corrected it, or chosen a different LED package.
Seeed used SFH-480 IR LEDs (SFH-482 compatible) on the production IR Toys so they matched the Eagle part footprint. This is a miscommunication on our part because any IR LED would have worked, but this part is also fine. Seeed assembled the LED according to the silk, which was backwards, thus all the emitters are backwards.
There is a self-test in the USB IR Toy, and despite the backwards LEDs, the self-test still passes. We’re guessing that there’s enough current leaking though the IR LED that it blinks dimly despite the incorrect placement.
You can repair your USB IR Toy by unsoldering the IR LED, and re-soldering it so the metal tab is opposite the silkscreen (facing the indicator LED ‘I’ and R2).
We should have caught this, and we’ll do our best to clean up the mess. Please contact us if you need to arrange a repair or a replacement LED.
This defect will be corrected in all future USB IR Toys produced.