ejparrott Posted November 29, 2011 Share Posted November 29, 2011 I'm helping a friend with his IIa rewire that has standard car horns of the spiral trumpet type (reasonable sounding for a change)...Whilest talking to him about all the work that needed doing, he mentioned that the horns had packed up. He remember that he'd had to insulate them from the bodywork, and suspected they must have come off a positive earth car, and guessed the reason for failure being the insulation failing. However..... I've took them off the rad panel and tested them on the bench tonight...after a bit of a scrub to get clean contacts they appear to be working again, but they don't seem to mind whether they are +ve earth or -ve earth....is this normal? Will they function both ways? It may be that after a damn good scrub to get the thick layer of years of grime off, and '+' or '-' symbol may appear next to the single solitary 6.3mm male spade fitting....just wondered if anyone knew the answer already? Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted November 29, 2011 Share Posted November 29, 2011 From memory they are just an electromagnet attached to bit of thin metal, when the magnet pulls it also breaks a contact that switches the magnet off, then it remakes contact and the cycle starts again...... this all happens very quickly and this is what makes the sound. So to cut a long story short ..... it's a magnet so doesn't care about polarity. HTH Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted November 29, 2011 Share Posted November 29, 2011 Just confirming what CwazyWabbit explained - didn't know about the way they function but certainly on my Series and 110 there's two 1/4" terminals and it doesn't care which way around they go. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted November 30, 2011 Author Share Posted November 30, 2011 Looks like its all good then! I'll get the carp cleaned off and see if there's any marked on the terminal, if not it'll go on -ve earth! Quote Link to comment Share on other sites More sharing options...
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