Dessicator

12 13 1 D3 10 216/9131N4148 R17 40p ICI IC2 N1...N4 = IC1 = 4001 N5 = IC2 = 4001 A1,A2 = IC3 = LM358 TIC206D La l L a2 CL.= Nom 78p C10 SI= T2On U D2 H 1N4007 impm 15V 680p 40ornw16V C6 Many of the smaller working areas available to hobbyists suffer from humidity, which in no time causes a number of tools to be covered in a thin layer of rust. Humidity does not do most test equipment or books and the like any good either. The only solution to this is to try to keep the area drier by increasing the tem- perature. A couple of 100 W light bulbs or a 100-200 W heating element work wonders in this respect, were it not for the increases in the electricity bill. And that is where the present circuit can help. With reference to the diagram, the two HEF4001Bs, in conjunction with humidity sensor H, generate a volt- age across R5that is directly pro- portional to the degree of humidity. The function of opamp Ai is merely to present a high impedance to U125. The voltage is then applied to th...