AC relay driving

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#1
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Hi there,

Could you tell me how can I drive a 230Vac coil relay?

Thanks,

Michael.

Michael.

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Actually, I would like to make a circuit that it will be supplied with 230Vac (only).
This circuit must have a delay (~5sec), before enables a 230Vac coil relay when it first been supplied.

Michael.

Michael.

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Triac with big RC?

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Why a big RC!!!! If you need to turn on/off it is not need snubber. if you need to dimming Yes a big RC!
A triac is the solution or a opto triac if need control form CPU & if the relay coil is not to big!
Thierry

Thierry Pottier

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Even if the relais is made with a 230 V AC coil, I would consider driving it with DC. AC Coils need more current/power and rend to produce a humming sound.

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I am agree with you. But power consum is not a big problem because use 230V not DC form CPU.
I has a similare project and use 230Vac because I could not have enough power form the serie capasitor.
By the way I have 2000 relay from Schrack 230ac coil 16A contact. very cheap!
Thierry

Thierry Pottier

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Big RC used for 5 sec delay.

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Even a triac used for on/off control needs a snubber. Incoming voltage spikes may still falsely trigger a triac in the off state.

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Not agree. Not need snubber for a relay but use a triac with good spec.
If you use very low gate current Yes snubber can be use but if you have no snubber & your current load is low ( like a std relay coil ) the risk to have a 10ms sinus in relay coil do not play a problem. It will not destroy the triac (it is why you must use a snubber not have unwanted switch & not destroy the triac)

I have make this application is more than 20000 pieces per year. It was to drive a relay for heating conrol.
There are many who follow the information read in an old book from school.
But the need for protection / snubber depends on the level of security you have with the project. If a switching of the relay is not acceptable: snubber + Use a zero cross drive.
The security / quality depend how much $ you can or must use for this.
I have make a lot low cost product and try some solution with less component than it needs. ( no snubber +++)

But people to talk of snubber for 5sec with you use 50Hz has not understand what a snubber is use for!

Thierry.

Thierry Pottier

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Is there any schematic to read and learn?

Michael

Michael.

User of:
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Altium Designer

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Teccor.com is a good start.
Philips & ST has (before) very good AN.
Thierry

Thierry Pottier