Hall Effect DC Speaker protection

[Spiny]

This was designed to provide protection for my bench speakers when building or fixing amps without being wired to the speaker leads/ground etc.

The design uses a hall effect sensor to detect current so no connection to the amp is needed (works with bridged amps).

The current trip level is set with a trimmer, I keep this on 2amps. Protection is via relay, fired by a triac to keep it in protect mode until turned off or reset. A lamp is in circuit with the relay to provide a large current on triggering and then as the filament warms the current is reduced to a holding level. This lamp acts as a protect warning lamp

The triac is a to92 high sensitivity type, the resistor on its gate needs selecting for the triac. A simple LED across the triac shows its working (triac not fired).

Power supply is +-12v but regulation is not needed. The unit I made uses a 9-0-9 transformer

Alan

[darkfenriz]

Nice. Hall sensors seem a good choice here, except for the price. The detector can be based on window comparator as well.

[Spiny]

Originally Posted by darkfenriz

Nice. Hall sensors seem a good choice here, except for the price. The detector can be based on window comparator as well.

I got these from Rapid (Rapid Electronics) part 82-1020 A1301EUA-T HALL EFFECT SENSOR
at the princely sum of £0.79 each +tax and shipping.
A window comparator would work well