30-08-2021, 11:16 AM
(30-08-2021, 07:26 AM)Slack Alice Wrote: I buy condensers like that from my local car spares shop - I ask for condensers with a wire coming out of them and they produce a selection.
H------s, the big car and cycle chain store would have them, too.
But what value (in uF and voltage) are they? "Modern" coil capacitors are usually 0.1uF but Magneto capacitors (apparently) should be between 0.1uF and 0.22uF (100 to 220nF), depending on whether they are rotating magnet or rotating coil types. 0.22uF is recommended for rotating magnet types, like the Lucas SR series. ( Magneto condenser theory (themagnetoguys.co.uk) ).
The other issue is that many of these odd capacitors are for supressing noise on in-car radio/stereos, heaven knows what capacitance values they will be and can they with stand the back emf generated by the magneto coil?
Using the advice on: Magneto condensers - practical (themagnetoguys.co.uk) , I'm trying to build a suitable replacement for my SR4 using the recommended RIFA capacitor, 0.22uF, 275VAC, which equates to about 600VDC. Having pulled one of the modern replacements apart, I was shocked at the poor design and workmanship, it's no surprise they're doomed to early failure.