Turn your Digital Voltmeter into an Inductance and capacitance meter. Page 1. Page 2. Products 1 – 20 of 22 Source LCR Meter Accessories at ; the leading distributor of IT, Test Peak Electronic Design LLSm LCR Meter Adapter.
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The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. Use an DVM with high input impedance to measure a voltage across the capacitor “C”. A switch S2 is used to configure the measurement circuit.
More precise measurements I do with a resonance bridge. The pulse width that is proportional to the inductance is made by drving the unknown inductance through a resistor and connecting the resultant sawtooth waveform to the input of another schmitt trigger which, because of the sharp switching action on its output that results from metdr hysteresis, provides a nice rectangualr pulse.
The voltage is negative. The circuit relies on a voltmeter with a millivolt range and a high input impedance as a readout device, so it doesn’t have a buffer incuctance the output. To participate you need to register. I used it when developing a d. The pulse width is proportional to the inductance and inversely proportional to the resistance.
When you built this, keep the connections, including gorund connections, short because tens of nanoseconds count. Any inductance in that path will add to the measured inductance, so keep it short and small.
When it switched into position “L”, the measurement circuit operates as an inductance meter, see the Fig.
LC Connector adapter
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The transistor Q1 is used to amplify the signal to provide sufficient current through potentiometer R8 and a load circuit.
Pay particular attention to the leads and contacts for LX. Connect a battery and a DVM digital volt meterput a known inductor in the LX position then adjust the potentiometer until you get the anticipated reading on the DVM.
Forums New posts Search forums. At first, adjust potentiometers R Started by fastline Yesterday at 8: Click here to register now. I calibrated my unit for uH, as this is the range I am generally most interested in, and it gives direct-readings on the uA scale of the meter. The Circuit The circuit’s operating principle is that if you make a pulse width proportioal to inductance, and keep the pulse frequency and amplitude constant, and then pass the pulse through a low pass filter so that only the average voltage comes out, the resulting DC voltage is proportional to the inductance.
Resource icon Inductance measuring adapter for multimeter The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings. I took this circuit from this page on the QRP Homebrew site and made some modifications to it, described below. Potentiometer Questions Started by norbss Yesterday at Welcome to our site! Here are some things to check when calibrating: The hysteresis in the schmitt trigger allows it to oscillate with the simple feedback circuit.
Here is the unit measuring a 33 uH commercial RF choke.
The procedure is straightforward: Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. Simple Audio Signal Injector Here’s a signal injector for those of us like me who don’t have a bench full mteer nice test equipment.
It also analyzes transistor’s characteristics such as voltage and gain. You might have some trouble getting the thing to calibrate if the switching thresholds on your 74HC14 are very different from the one I used, so you might have to change the resistance in the osicllator or the capacitor in order to claibrate the circuit.
If you find the voltage to be very low, say under a volt, then this points to a wriing error, a problem with the 5V regulator or the battery, a damaged 74HC14, or you are using a very low resistance voltmeter. Inductors with ijductance cores, high permeability ferrites, or with large amonts of shunt capacitance cannot be measured accurately.
Replacing a 4 pin leaded inductor with a 2 pin Started by gkmaia Yesterday at To my surprise, it actually worked just fine, 1K in series was sufficient to allow a useful calibration and didn’t overload the drive capabilities of the last gate in the package. Media New media New comments Search media.
MFJ Enterprises Inc.
Just saying hello Started by MichaelaJoy Yesterday at 6: Check out inductancs five ranges. The last inverter in merely 68 make the pulse positive in polarity so ijductance the voltage increases as the inductance increases. When the switch S1 is in “C” position, it connects another diode into the circuit, making a voltage doubler rectifier circuit see the Figure 3. This RC network operates as an integrator circuit. Author carbonzit Creation date May 25, There is a way to check out the duty cycle at the collector of Q1.
The switch S2 is in position “L”. Articles Top Articles Search resources. Inductance Meter In-Use The resolution of the analogue meter obviously limits its performance, but I generally use it to just ensure I am in inductahce right ballpark while winding coils or picking from the junk box.
It works as an oscillator whose frequency is determined by the RC components R Real-Time ‘Stopwatch’ This is a simple electronic “stopwatch” you can use to time an event. The output waveforms can be both amplitude and frequency modulated.