Archive for the ‘Testing and Measurement’ Category
LM134-LM10 Thermometer/Temperature Sensor
Using LM134 and LM10 integrated circuits, we can build a thermometer which has -55 to 150°C sensing range. The ideal meter for this circuit is a 0-200uA digital ampere meter, which can show both positive and negative polarity. This will make the circuit suitable for indicating temperatures below 0°C. LM134 is basically a current source …[Read More]
Battery Level Indicator
A battery level indicator circuit is depicted in the schematic diagram below. This circuit is designed for 9V battery operation, as this circuit will start dimming below 7V and will be completely turned off at 6V. If you want the LED indicator not to dimming but just abruptly turns off at below 6V, then you …[Read More]
Using LM10 amplifier and voltage reference, a light intensity meter featured with five decades dynamic range (which is suitable for photographic application) can be built. Please note that the linear to log conversion is not temperature compensated, and can make 40% error (a half stop in photography) at the worst point of conversion slope at …[Read More]
Chromel Alumel Thermocouple Current Loop Transmitter
The schematic diagram below show signal conditioning circuit for remote current loop temperature transmitter. This thermocouple temperature transmitter is loop powered, means it doesn’t need its own power supply since the supply is provided by the current loop receiver. Thermocouple is basically a junction of two different metallic material that measures the temperature difference. This …[Read More]
Current Loop Light Level Detector
This circuit is two wire light level detector, we don’t separate wires for power this sensor system and for delivering the output signal. With current loop, we do both function in a single pair of cable, just provide the voltage supply and measure the current as the output signal. The core of this circuit is …[Read More]
10 mA, 100 mA, and 1 A Current Source
The circuit of the milliohm adapter is shown on the following figure. Under test, it can apply 1 A, 100 mA, or 10 mA to the resistance. If your voltmeter is set on the 2 V range, the current application will indicate the resistance directly in millivolts. B1 is the high current source. B1 is …[Read More]
Single-Cell Voltage Monitor
Monitoring battery voltage can be important in some application. Some battery monitor will be simply a continuous LED lamp which is dimming according to the voltage level. Here is presented monitoring circuit that flashing, which is more noticeable than simple dimming the light intensity. At 1.2V, the LED begin flashing, and the flashing rate will …[Read More]
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