What is the watt rating on each of those cob chips?
Sure, you can grow using a cob LED. However, the one thing to keep in mind about COBS are their intensity. Its why I asked what the watt rating on those chips are. You will want to pay close attention to whether or not you have your DIY cob light at a distance the plants can handle. COB have a higher propensity to burn your plants if they are too close. The burning is created by light intensity, not heat.