I bought a bunch of CA3140s on eBay from a vendor in China. They were inexpensive, so I thought I'd roll the dice. I wanted to perform a quick check to see if they were functional and had MOSFET inputs, so I whipped up this little circuit. Out of the first 10 I tested, all were functional but two were funky. The blink rate was slow and asymmetric (longer off time than on time) on the funky ones. This indicates excessive leakage current on the input. I paid less than $20 for 50 of 'em, so I can't complain if a few of them turn out to be stinkers.