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| How to switch a speaker on and off? |
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| Chris C:
Yep, a decent amp should have at least some protection against inductive spikes built-in. Otherwise, any time you had a loose speaker wire, you'd blow the amp. However, an SSR may or may not have this protection. It can be added by putting two zener diodes in series, but facing in opposite directions, across the SSR; with the zener voltage being less than the maximum voltage of the SSR. (Or a TVS, which is equivalent to two zeners.) You may be able to get away without that, if you're: 1) Switching the SSR slowly enough that an inductive spike doesn't develop. 2) Switching only a secondary parallel speaker, leaving the primary speaker connected at all times; which gives the spike a path to travel through, so it won't rise to a particularly high voltage. But I'd be more comfortable with the zeners. Cheap insurance. |
| Starlord:
--- Quote from: Chris C on July 31, 2015, 01:53:49 pm ---Yep, a decent amp should have at least some protection against inductive spikes built-in. Otherwise, any time you had a loose speaker wire, you'd blow the amp. However, an SSR may or may not have this protection. It can be added by putting two zener diodes in series, but facing in opposite directions, across the SSR; with the zener voltage being less than the maximum voltage of the SSR. (Or a TVS, which is equivalent to two zeners.) --- End quote --- So wire them cathode to cathode or anode to anode (which way doesn't matter?) across the SSR's output pins? Or use a TVS? When you say Zener voltage do you mean breakdown voltage or voltage drop? And is there a way I could tell if the SSR has these diodes even if they're not shown in the schematic? Some spec that would give their presence away? --- Quote ---You may be able to get away without that, if you're: 1) Switching the SSR slowly enough that an inductive spike doesn't develop. 2) Switching only a secondary parallel speaker, leaving the primary speaker connected at all times; which gives the spike a path to travel through, so it won't rise to a particularly high voltage. But I'd be more comfortable with the zeners. Cheap insurance. --- End quote --- Number 2 would be likely true most of the time, but I can't trust that will always be the case. |
| Chris C:
--- Quote from: Starlord on July 31, 2015, 02:16:23 pm ---So wire them cathode to cathode or anode to anode (which way doesn't matter?) across the SSR's output pins? Or use a TVS? --- End quote --- Yes. --- Quote from: Starlord on July 31, 2015, 02:16:23 pm ---When you say Zener voltage do you mean breakdown voltage or voltage drop? --- End quote --- Breakdown voltage. For example, the 1N4749 is a 24V zener, and might be a good choice for the CPC1020N (30V max). --- Quote from: Starlord on July 31, 2015, 02:16:23 pm ---And is there a way I could tell if the SSR has these diodes even if they're not shown in the schematic? Some spec that would give their presence away? --- End quote --- Not sure on this class of components. In general I'd look for phrases like "ESD", "inductive spike", or "overvoltage" protection on the output. I noticed "Arc-Free With No Snubbing Circuits" on your pick, that might be significant or just mean no dV/dT triggering (a different issue with TRIACs), I don't want to falsely assume. |
| dashpuppy:
Did anything ever come of this ? |
| Audioguru again:
A speaker makes a POP sound if it is switched at the peak of the signal. To avoid the POP then mute the signal, switch the speaker then unmute the signal. The mute and unmute must be ramps, not abrupt changes. |
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