10 years ago.

Printer toner cartridge chips technology

I'd like to put my limited electronics knowledge to good use but have struggled to think of a worthwhile project. After building an ECG using an mbed and a handful of components I ran out of original ideas. I'd like to understand the technology used in toner cartridge chips which stops them working after so many pages. I have a pretty good Dell laser printer which didnt cost very much.Of course the cartridges are ridiculously expensive. I buy in chips from Shenzen and refill the cartridges saving 80% of cost of replacement cartridge. I'd like to know how the chips work and I'd like to make my own chips also. Can anyone give me a steer in the right direction ? If they can do it in China.......

Here is a picture of the chip used in my Dell 2335 printer. I have identified the 8 pin Atmel AT88SC chip but I dont know what the 20 pin square device is or what it does. I'm hoping there may be some way to reverse engineer the chip and read the programming. I assume the 6 copper pads are used during manufacture for programming the devices. Any comments will be read with interest.