Hello, I have a small problem. Solenoid has a resistance of 14.2 ohms and an inductance 0.056H is connected in series with a resistance 2.2Ohm Thus calculated is the Tau = L / R = 0,056 / (14.2 + 2.2) = 0.0034s But the measured value is 0.02s The measurement is done on an oscilloscope for resistance. Source is a classic laboratory. If I measure only air-core coil corresponds to the time constant. How is it possible that tau is based on much more? Solenoid Type: Code (Text): http://docs-europe.electrocomponents.com/webdocs/001b/0900766b8001b732.pdf [/ code] Thank you for your response.
Did you measure with the plunger extended or retracted? Plunger position will probably have a significant effect on inductance. Edit: I don't think you should count the 14.2 Ohms as being in series with the coil when calculating Tau. So Tau = 0.056/2.2 = 0.025 s
Why? A formula please? Coil having no core has a smaller inductance. This coil inductance and resistance 0.012H and 14.2Ohm 0.0012 / (14.2 + 2.2) result corresponds approximately
LCR-9073 METER L=0.056H http://www.lion.co.il/site/HvDest/LCR9073.pdf and Digital LCR METER DT-9935 for: 100Hz L = 0.084HH 120Hz L = 0.07896H 1000Hz L = 0.031250H 10kHz L = 0.0127H 100kHz L = 0.007H http://www.selectronic.fr/media/pdf/910111.pdf I measure my response to a step change on the oscilloscope or rectangular pulses, as the input voltage.