In some newspapers before one can often see a number of electronic memory enhancer of the ad, said that the enhancer is Japan's latest research results, talk about how how you can greatly increase the effect of human memory, it is a lot of student friends to buy it , then I have seen the students around us to buy this thing, I try, have a certain effect, in fact, a low-power audio amplifiers, many of these circuits, you can use transistors, or integrated circuits, such as the LM386 , TDA2822, etc., the principle is very simple, even if you have not done electronics from a small production, according to the following can be done out of the circuit and the circuit components are cheap, the market is easy to buy. I recommend this circuit, because I had previously done, but also very practical, especially student friends, why buy that the price is not cheap and poor quality video machines to learn it, the circuit is very simple, unnecessary circuit boards, directly take Welding can be shed, with two 5 batteries can and do well into the small tape cartridge in the headphone jack Note: TDA2822 only one channel.