Headlight bulb load quickfix

Recently a 13.8V 25A DC Linear Regulated Power Supply was in need of testing after its defective main rectifier was replaced. It had protective circuits for under-voltage, over-voltage, short-circuit and over-current.

A couple of 12V 55/60W headlight bulbs were used to load the power supply, but their very low cold resistance caused instant tripping.

A length of galvanised curtain wire (~ 1.5m long), connected in series, saved the day. The power supply did not trip and the bulbs emitted a feeble glow.


The connecting wire was then slid along the curtain wire. The illumination progressively increased and so did the load current. When the curtain wire went out of circuit, the bulbs were fully illuminated and drawing 23A from the power supply.
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