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Qrp Hf Swr Meter – Circuit Schematic
Qrp Hf Swr Meter
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Dc Voltage Meters – Circuit Schematic
Dc Voltage Meters
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Digital Frequency Display – Circuit Schematic
Digital Frequency Display
The back to back diodes are there because some radios present high voltage transients when switching bands which will lock up the DFD requiring it to be turned ...
Instrumentation circuit – Circuit Schematic
Instrumentation circuit
The mechanical chassis prototype, as can be seen from the image on the left, was made using two materials: foam and aluminium. Foam was chosen due to its easy m...
Enlarging Light Meter Circuit – Circuit Schematic
Enlarging Light Meter Circuit
Meter Ml, a +/-50-uA zero-center D`Arsonval meter movement is driven by Ul, a TL081 FET op amp, through R3. The gain of Ul is set at 11 by Rl and R2, while cap...
Frequency Divider For Measurements Circuit – Circuit Schematic
Frequency Divider For Measurements Circuit
This circuit is meant to be driven by a 1-MHz standard signal of a few volts amplitude. Ul through U5 are 7490 decade counter/divider and produce a division ra...
Continuity Tester For Low-Resistance circuits – Circuit Schematic
Continuity Tester For Low-Resistance circuits
The continuity tester is little more than a battery and a lamp connected iri series, with one end of the string terminated in an alligator clip,...
Linear Inductance Meter Circuit – Circuit Schematic
Linear Inductance Meter Circuit
Using the fact that in an RL circuit, the pulse width seen across the inductor is proportional to the inductance, this circuit reads this indirectly on a DVM....
Digital Pressure Gauge Circuit – Circuit Schematic
Digital Pressure Gauge Circuit
This electronic pressure gauge uses a Wheatstone bridge-type pressure sensor tb drive a 3 A digit A/D converter and a display. IC1 is a pump (quad) that interf...
Short Tester For 120V Equipment Circuit – Circuit Schematic
Short Tester For 120V Equipment Circuit
Do you deal with old equipment in unknown condition If so, this little circuit could keep you from causing further harm...
1Khz Harmonic Distortion Meter Circuit – Circuit Schematic
1Khz Harmonic Distortion Meter Circuit
The circuit useful for distortion measurements notches out the fundamental frequency of 1 kHz to allow measurement of the residual level of harmonics. First a ...
Led Expanded Scale Voltmeter Circuit – Circuit Schematic
Led Expanded Scale Voltmeter Circuit
A10-V zener diode is used to expand the scale of a 0- to 5-V voltmeter to a 10- to 15-V voltmeter. The LED bar graph lights one segment per 0.5-V input above 1...
Fast Video Signal Amplitude Measurer Circuit – Circuit Schematic
Fast Video Signal Amplitude Measurer Circuit
Video-signal amplitude can be measured with this simple circuit, which is basically a modified standard peak detector. The device can verify RGB generated by v...
One Ic Capacitance Tester Circuit – Circuit Schematic
One Ic Capacitance Tester Circuit
This circuit can be used to match capacitors, etc. The dc output voltage is related to the capacitance values of Cx. The circuit values shown are for capacitor...
Audio-Frequency Meter Circuit – Circuit Schematic
Audio-Frequency Meter Circuit
This meter differs from the norm in that it does not use a D`Arsonval movement or digital display to give a reading of the input frequency. Instead, the measur...
Ac Watts Calculator Circuit – Circuit Schematic
Ac Watts Calculator Circuit
The load`s power factor, which is the cosine of the phase angle between the voltage across the load current, can be calculated simply with this circuit. A1:1 i...
Low-Drift Dc Voltmeter Circuit – Circuit Schematic
Low-Drift Dc Voltmeter Circuit
This voltmeter uses a pair of JFETs in a balanced-bridge source-follower amplifier circuit. Q1 and Q2 should be matched within 10% for IDSS. ...
Simple Curve Tracer Circuit – Circuit Schematic
Simple Curve Tracer Circuit
Useful for checking diodes, transistors, triacs, SCRs, resistors, and LEDs, this curve tracer should prove useful in the experimenter`s lab. It displays the vo...
Cable Tester Circuit – Circuit Schematic
Cable Tester Circuit
At the heart of the cable tester are two op amps, which are used as a window- comparator to indicate a short- or open-circuit condition. A third op-amp compara...
Electronic Scale Circuit – Circuit Schematic
Electronic Scale Circuit
An electronic scale using a pressure transducer (load cell) and an analog-digital (A/D) converter to drive a digital display is shown. The scale range depends ...