In theory buffer stock schemes should be profit making, since they buy up stocks of the product when the price is low and sell them onto the market when the price is high. However, they do not often work well in practice. Clearly, perishable items cannot be stored for long periods of time and can therefore be immediately ruled out of buffer stock schemes. Other problems are:
Buffer stock schemes seek to stabilize the market price of agricultural products by buying up supplies of the product when harvests are plentiful and selling stocks of the product onto the market when supplies are low.
The White cathode follower, named after its inventor Eric White, is a useful improvement over the conventional cathode follower. How so? It is a push-pull buffer design that allows the delivery of up to twice the idle current into the external load impedance. The cathode follower's cathode resistor is replaced by a triode that actively responds to the input signal, so that the White cathode follower's output can aggressively pull and down. In contrast, a conventional cathode follower can only robustly pull up, relying on the cathode resistor's passive doward tug to pull the output down. Surprisingly enough, in spite of its push-pull operation, the White cathode follower accepts an unbalanced input rather than a balanced one. In addition, the White cathode follower can present a lower output impedance than the conventional cathode follower, coming in at 50% lower—or even lower...
One way to smooth out the fluctuations in prices is to operate price support schemes through the use of buffer stocks. But many of them have had a chequered history.