a/c circuit transient suppression
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Hi David,
Try using two V47ZA1 varistors (or the equivalent), one across the
solenoid coil and the other across the output of the 24VAC transformer.
Also, put a 0.1 muF 50V ceramic capacitor across the output of the
transformer, and (what the heck) across the input of the transformer put
a V130LA20A varistor.
cheers,
Bill Porter
> Here's the situation: I've got a bs2 controlling a 5vdc relay which switches a
24vac sprinkler valve controller. The power supply for the whole setup is a
24vac transformer; I'm using a bridge and regulator to cut it down to 5vdc for
the electronics (with lots of filter caps) and it also powers the valve selenoid
directly via the relay. I've got a rectifier across the relay coil to clamp
spikes, but I have a feeling I need something across the selenoid (something
called a snubber, perhaps?) to block spikes generated by it during switching.
The system behaves somewhat irratically when the selenoid is switched on and off
(scope -- set for a/c, 2v/div -- seems to show occasional spikes during the
switching), it behaves fine without the selenoid, and also with the selenoid if
I put a cap across it (probably not a great idea since it's driven by a/c).
I'm not that familiar with a/c circuit transient suppression, and would
appreciate any insights.
Try using two V47ZA1 varistors (or the equivalent), one across the
solenoid coil and the other across the output of the 24VAC transformer.
Also, put a 0.1 muF 50V ceramic capacitor across the output of the
transformer, and (what the heck) across the input of the transformer put
a V130LA20A varistor.
cheers,
Bill Porter
> Here's the situation: I've got a bs2 controlling a 5vdc relay which switches a
24vac sprinkler valve controller. The power supply for the whole setup is a
24vac transformer; I'm using a bridge and regulator to cut it down to 5vdc for
the electronics (with lots of filter caps) and it also powers the valve selenoid
directly via the relay. I've got a rectifier across the relay coil to clamp
spikes, but I have a feeling I need something across the selenoid (something
called a snubber, perhaps?) to block spikes generated by it during switching.
The system behaves somewhat irratically when the selenoid is switched on and off
(scope -- set for a/c, 2v/div -- seems to show occasional spikes during the
switching), it behaves fine without the selenoid, and also with the selenoid if
I put a cap across it (probably not a great idea since it's driven by a/c).
I'm not that familiar with a/c circuit transient suppression, and would
appreciate any insights.