Light Powered Thermometer

64 EE January 1988 2 03 ■I • AA119 r- -0" T L _rf *R7 bias setA 4 3 2 8 _J 01 72 R11 BC54713 100n 0 IN LO 26 V- OSC1 OSC2 OSC3 C REF REF LO 35 BUFF INT BS170 P2 R3R8 LCD IMEIMMEI0 a 2 11131 TLC +a +271 IC 3 02 1191-j 4709 169 +VS IC 2 oot 22 7 BP 21 TEST 37 BS170 04 Fig. 2. Circuit diagram of the light powered thermometer. LIGHT POWERED THERMOMETER An accurate, automatically operating electronic thermometer that indicates temperature on a digital readout without the need for batteries or a mains supply. The thermometer described here is pow- ered by an amorphous solar cell. In con- trast to other types of solar cell, this uses a non-crystalline silicon layer. Amorph- ous solar cells are produced by con- trolled deposition of silicon on a glass surface, which forms the top of the cell. The production method is relatively simple and cost-effective, but has the disadvantage of yielding cells with a relatively low efficiency. The basic struc- ture of an amorphous solar cell is ...