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 pulse width is proportional to the inductance and inversely proportional to the resistance. 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 on the output.
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FOA – LC Connector adapter
If yours runs at a greatly different frequency, try changing the oscillator components or try using a 74HC14 made inducgance a different manufacturer. Welcome to our site!
The source of the voltage is negative pulses across the inductance Lx. Pay particular attention to the leads and contacts for LX. In order to get a pulse with a width that is substantiall longer than the rise and fall time of the schmitt trigger, whcih is a requiremnt for good linearity, while the inductance was in the nH range, I had to use a very low resistance, hence the three ohm resistors and their drivers in parallel.
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. More precise measurements I do with a resonance bridge. The last inverter in merely to make the pulse positive in polarity so that the voltage increases as the inductance increases.
The transistor Q1 is used to amplify the signal to provide sufficient current through potentiometer R8 and a load circuit.
If not, you may have too much inductance in the leads to LX or have connected LX to a noisey ground point. This circuit is only accurate for broadband inductors. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc.
Any inductance in that path will add to the measured inductance, so keep it short and small. It also analyzes transistor’s characteristics such as voltage and gain.
You can control lights, fans, AC system, computer, printer, amplifier, robots, garage door, security systems, motor-driven curtains, motorized window arapter, door locks, sprinklers, motorized projection screens and anything else you can think of. Media New media New comments Search media. The hysteresis in the schmitt trigger allows it to oscillate with the simple feedback circuit.
The pulse frequency is set by a schmitt trigger oscillator meyer of a feedback resistance 2k pot and 3.
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.
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Inductance and capacitance meter adapter for DVM
At first, adjust potentiometers R There is a way to check out the duty cycle at the collector of Q1. The procedure is straightforward: A two deck rotary switch S1 selects one of five measurement ranges. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Here is the unit measuring a 33 uH commercial RF mdter.
If it isn’t, its probably because the thresholds on the 74HC14 are not symmetrically positioned around mefer.