Vision

To reduce the occurances of failed products due to faulty coils

Rationale

One particular product relied on a specific arrangement of four electromagnets. The product would not work if any of the electromagnets were out-of-spec or wired incorrectly. Following a short investigation, I noticed that 5% of the products would fail due to issues with the electromagnets, but there was no way to identify the cause of the issue. The current check was to only to measure the resistance of the coil.

Feature

• Mounting post with secondary coil
• Character LCD
• Resistance measurement
• Polarity identification

Realisation

The test fixture was designed to accept the electromagnet in one orientation only. This way I could control the polarity of the coil, and introduce a secondary coil forming a simple transformer. A h-bridge circuit was used to energise the electromagnet and detect the resultant waveform in the secondary. The current was measured through the electromagnet to determine the equivalent resistance. Finally, the relationship between the signal voltage and current was used to approximate the inductance of the electromagnet. This test equipment was used to identify that the majority of electromagnets that were attributed to a failed producted were had an incorrectly labelled polarity.

Future

N/A