The output remains on for a time interval determined by R and C. The resistor can be a 10 kΩ or higher unit, and C must have values in the range between 1 nF and 1,000 uF. Using a 1,000 uF capacitor and a 1 MΩ resistor, the circuit, once triggered, will remain on for about 15 min.
Figure 1 - Temperature/light-dependent oscillator.
