While exploring alternatives, the idea arose to use a photocell instead of any ordinary voltage converter. It resulted in the circuit in Figure 1. Figure 1 Using photocells instead of a voltage ...

2 CdS photocells (The Electronic Goldmine #G14025; $3.00) 2 (0.01 mF) ... Install the complete circuit inside the box. Mount the two CdS photocells externally on opposing sides of the box.

Since the measurement is based on detecting the photocell current in situ, ... Lund University, Box 124, Lund, 22100, Sweden. Khadga J. Karki, Joachim Seibt & Tõnu Pullerits.