Snubber, Relays and Solenoids

[kadini]

Trying to make a circuit with a solenoid that pushes the reset button on a streaming device.

Started this thread earlier in another post but it got kind of long and didn't seem like anybody was following it anymore.

Simple question I hope. For a 12v DC solenoid actuated by this relay https://www.ebay.com/itm/224370769091?hash=item343d8a3cc3:g:q64AAOSw8HpgPbwq&LH_BIN=1 do I need a snubber in the circuit (see attached sketch generated by another member of this forum).

I had never heard of a snubber before (at least not in the context of circuits). Reading around it seems like they are used to prevent arcing at switch contacts. But is the NE555 relay a solid state device? And, if so there aren't any contacts and a snubber wouldn't be needed?

Or, if it isn't solid state can somebody tell me which diode to use in the circuit? And I assume it's wired in parallel between the 2 wires coming out of the solenoid?

Thanks.

 

[MaxHeadRoom78]

With a DC device, a reverse connected Diode is usually used across the coil 1n4007 etc.

 

[kadini]

So the positive end of the diode goes to the negative wire and the negative end to the positive wire? That's reverse connected?

 

[danadak]

 

[eTech]

So the positive end of the diode goes to the negative wire and the negative end to the positive wire? That's reverse connected?

So there is no confusion, a general purpose diode has two terminals (or wire leads). One terminal is the "anode" and the other is the "cathode".
The diode is usually marked with a silver or white band around one end of the body. The band identifies the "cathode".

Reverse connected means that it is connected so that no "forward" current flows. So a reverse connected diode (or snubber) has the band connected to the positive side of the coil, and anode connected to the negative side of the coil.

The coil of a solenoid is a type of inductor and an inductor can store energy when energized. When the coil de-energizes, its magnetic field collapses and releases the stored energy in the form of a short electromagnetic pulse. The pulse can interfere with the operation of (or damage) solid state electronics. The "snubber" diode will short circuit the pulse to ground where it can do no harm.

Hope that helps...

 

[crutschow]

The "snubber" diode will short circuit the pulse to ground where it can do no harm.

Or back to the negative solenoid terminal.

The diode allows the inductive solenoid current to keep flowing when the controlling switch is opened, until all the inductive energy is dissipated in the diode and solenoid resistance, instead of at the switch.

 

[kadini]

Think I finally have it.

Thanks!

 

[kadini]

Does the voltage of the diode matter?

If it's way bigger than 12V is that ok?

 

[danadak]

If its 50V or higher that will give you plenty of margin.

Regards, Dana.

 

[MaxHeadRoom78]

A typical one I keep on hand that covers many low power eventualities is the 1n4007.
If the coil is high power/inductance you will need a higher current value.

 

[kadini]

Solenoid is 12V DC with 2.5 watt power draw.

I don't know but assume that's not high/power inductance?

So this diode should work?

10pcs 1N4007 Rectifier Diode 1A 1000V - US Seller | eBay

For sale are 10pcs of MIC 1N4007 1 amp 1000 volt Rectifier diodes.

www.ebay.com

 

[eTech]

Solenoid is 12V DC with 2.5 watt power draw.

I don't know but assume that's not high/power inductance?

So this diode should work?

10pcs 1N4007 Rectifier Diode 1A 1000V - US Seller | eBay

For sale are 10pcs of MIC 1N4007 1 amp 1000 volt Rectifier diodes.

www.ebay.com

That will work just fine...

 

[MaxHeadRoom78]

That will work just fine...

+1