| Electronics > Beginners |
| Old DC current measuring device |
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| nForce:
This is a very old concept, maybe in the 70' were these devices used for measuring DC current: https://imgur.com/a/D9fjKFY Does anyone understand how it works? In this schematic I1 is a DC current we are measuring, U~ is AC voltage. I think other signals are clear enough. |
| Kleinstein:
This looks like a kind of transductor cor magnetic amplifier circuit. It usually requires inductors cores that are easy to saturate and high ยต. An external current (usually rather large) drives the cores more towards saturation. This increases the AC current flowing through them. Using the 2 Transformers in series, but with opposing primary keeps the AC voltage appearing at the measured circuit small. |
| coppice:
The diagram is rather minimal, but this looks like a flux gate sensor. There has been a resurgence of activity with these, based on recent techniques for making them very small. |
| nForce:
Thanks, I have a few questions: What does the single phase rectifier do? And that ammeter, so here we are measuring this DC current I1? --- Quote ---This increases the AC current flowing through them. --- End quote --- Why is there an increase of AC current, when we saturate cores? |
| glarsson:
The rectifier turns the AC current (I2~) into a DC current (I2=) that can be measured by the ampere meter. The current is proportional to the big I1 we are trying to measure. The AC current through a cored coil or transformer is restricted by the magnetic field created by the current itself. When the core saturates the current increases dramatically as there is ni longer much to stop it. This is what happens when a 130V Weller soldering station is connected to 220V. |
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