Archive for the ‘Testing and Measurement’ Category
1 KW Power (Watt) Meter
This watt-meter circuit has measurement range up to 1-KW. This circuit can give the complete (X)(Y) function although uses only one transistor. Actually, this circuit is used for 117 Vac±50 Vac operation. For lower or lower voltage, this circuit can be modified easily. This circuit only measure power on negative cycles. The advantages of this …[Read More]
Voltage and Current Limited Audible Continuity Tester
Using this continuity tester circuit, a failure of PCB tracks be examined without looking directly at the tracks routing, which is can be very frustrating. The indication of this circuit is done by an audible alarm (a buzzer). This circuit can be used to indicate continuity below any resistance value up to 35 ohms by …[Read More]
This is a schematic diagram of auto fuse monitor circuit. This circuit is very useful for automobile application, checking a live fuse without wasting any electrical power if the fuse is working fine. This circuit can check the fuse without removing the fuse from the working circuit. When the fuse is being tested, this fuse …[Read More]
LF356 4-Ranges Ac Millivoltmeter
This is a 4-range AC millivolt meter circuit. This circuit is used to measure a AC voltage in millivolt range. This circuit has frequency response of a few Hz to about 50 kHz. The non-linearity of the rectifier circuit is eliminated by placing the rectifier inside the op amp feedback path. This circuit read the …[Read More]
Low Power Under- and Over-Voltage Monitor
This voltage monitor has two threshold, VTH for undervoltage and VTH’ for overvoltage. Using the component values shown in the schematic diagram below, this circuit give 6V for VTH and 15V for VTH1. Above 6V, the LED indicator of this voltage monitor circuit will increase the flash rate until reach 15V. This circuit will stop …[Read More]
Logarithmic Amplifier Using MC1556 Op-Amp
The circuit below is a logarithmic amplifier using an MC1556 op amp. The 10K pot is an offset adjustment. Here is a schematic diagram of one classic example of general purpose logarithmic converter circuit employing LM1556 op-amp: The popularity of logarithmic amplifier is decreasing as the microprocessor and microcontroller chips are getting lower and lower …[Read More]
Single Cell Battery Meter Amplifier
A meter amplifier can be designed using LM10 integrated circuit (IC). The accuracy of full-scale sensitivity is good for over 15°C to 155°C at 10mV and 100nA. Here is the schematic diagram of the circuit: R5 is used to correct the offset voltage error, while R4 is used to balance the bias current. The zero …[Read More]
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