Over-Temperature Switch The output goes high when a preset temperature is exceeded. A fixed half-supply reference voltage feeds a reference current to the inverting input, and a variable current is fed to the noninverting in ... read more>>
Heater Control This proportional control crystal oven heater uses lead/lag compensation for fast setting. The time constant is changed with R4 and compensation resistor R5. If Q2 is inside the oven, a regulated supp ... read more>>
Electronic Thermometer An inexpensive electronic thermometer is capable of measuring temperatures over a range of from -30 degree F to +120 degree F. A diode-connected 2N3904 transistor used as the temperature sensor forms ... read more>>
Digital Thermometer The sensor consists of two series-connected 1N914s, part of the circuit of a 555 multivibrator. Wired as shown, the output pulse rate is proportional to the temperature of the diodes. This output is f ... read more>>
Differential Thermometer The differential thermometer uses two probes and shows the temperature difference between them, rather than the exact temperature. The thermometer uses a conventional meter as an indicator, and it cov ... read more>>
