Digital thermometer
The described sensor utilizes two 1N914 diodes connected in series to form a temperature-sensitive component within a 555 timer-based multivibrator configuration. The 555 timer operates in astable mode, generating a continuous square wave output. The frequency of this output is influenced by the forward voltage drop across the diodes, which varies with temperature. As the temperature increases, the forward voltage drop decreases, resulting in an increase in the output frequency of the multivibrator.
In this configuration, the diodes serve as temperature sensors, with their characteristics allowing for a direct correlation between temperature variations and the output frequency. The output pulse rate from the 555 timer is then directed to a frequency-counting circuit, which can be implemented using a microcontroller or a digital frequency counter. This circuit counts the number of pulses in a given time frame, translating the frequency into a readable temperature value.
The frequency-counting circuit may include components such as a microcontroller with an integrated timer or an external counter IC. The microcontroller can be programmed to convert the frequency into a temperature reading, which can then be displayed on an LCD or sent to a computer for further analysis.
Overall, this setup provides a simple yet effective method for temperature measurement, leveraging the characteristics of the 1N914 diodes and the versatile 555 timer to create a reliable temperature-sensing circuit.The sensor consists of two series-connected lN914s, 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 fed to a simple frequency-counting circuit. 🔗 External reference
Related Circuits
The ATmega8 microcontroller-based Low-Cost Telemetry Device (LTD) is an efficient telemetry keyer. The LTD measures the voltage levels of up to four analog channels via its on-chip 10-bit ADC, converts the measurements to numbers, and then sends the data...
Figure 7-2 illustrates the FSK (Frequency Shift Keying) signal demodulation circuit, which is built using a digital phase-locked loop. This circuit features two oscillators operating at distinct frequencies: crystal oscillator X with a frequency of 983.04 kHz and crystal...
The following circuit is a PC thermometer utilizing the DS1621. Features include the ability to plug into any available PC COM port, a temperature range of -20 to 125°C, and the capability to display temperatures in both Celsius (°C)...
This circuit relies on the input of a correct sequence code. An incorrect number that is not part of the code triggers a reset of the circuit. When the correct code is entered, Q2 activates relay K1 for a...
This circuit provides a visual 9 second delay using a 7 segment digital readout LED. When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high....
This circuit illustrates a display driving system for a digital voltmeter. The liquid crystal display (LCD) does not emit light by itself; it relies on external incident light for visibility. The integrated circuit (IC) LD130 serves as an input...