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I need a simple curcuit ? Answered

I need to turn on a 24vdc relay (apply gnd ) with a transistor. I have a 5v signal as the sourse from an industrial computer

Tags:dave

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rickharris

4 years ago

Like this? Of course you need a 5 volt relay coil if you have a 5 v supply

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daveaprilerickharris

Answer 4 years ago

my sourse to activate the transistor is 5 v but rtelay coil is 24vdc

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rickharrisdaveaprile

Answer 4 years ago

IF your going to use one relay to turn on the 24 volt relay you need a 24 volt source anyway, unless there is something your not saying you may as well just use the 24 volt source you will need anyway and a single relay driven by the transistor.

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petercddaveaprile

Answer 4 years ago

There's probably a better way to do it electronically, but I'd use the 5V relay to switch on the 24V power to the 24V relay.

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steveastroukpetercd

Answer 4 years ago

You shouldn't drive the relay directly from the computer I/O pins

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petercdsteveastrouk

Answer 4 years ago

Actually I was thinking of an addon mod to the Rickharris circuit, meaning use that 5v relay to drive the other 24v one.

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steveastroukdaveaprile

Answer 4 years ago

That will work just fine on 24V. Just don't forget the diode, its critical.

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rickharrisdaveaprile

Answer 4 years ago

The transistor will turn on fully when it's base is at about 1 volt. In this diagram the relay has a 5 volt coil. but your is 24 volts (I assume that's what you mean) - replace the 5 volt supply with 24 volts and yours will work.

The BCX38C can handle up to 60 volts collector to emitter at 800 Ma.

If your only supply is 5 volts then you need to find a relay that operates off

5 volts