in this circuit FWD/RVS relay is shown with 2 separate contact pins and 2 separate NC and NO pins...

i wanna ask whether they are using 2 relays with one transistor or configuration of relay is just like that internally..?

Attached Images

relay-motor.gif (9.8 KB, 27 views)

 

It's two relays, and clearly shown as such. One is used for ON/OFF and the other for reversing.

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i m not talking abt above power relay..
the 2nd FWD/RVS relay...???

 

It's a DPDT relay, also called a 2 pole changeover, again it's clearly marked as such, by the dotted line from the coil to the contacts. It's a standard relay!.

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yeah.. nigel is right

 

hmm...in this case if i dont use that relay...can i use two simple relays with one transistor?

 

You could use two single pole changeover relays - assuming you already have them? - if not you may as well get the correct relay, like I said they are VERY common.

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im not been able to switch two single pole relays with one transistor(2n2222).

 

hi,
What are your base drive voltage inputs, if they are +5V, its most likely that with a 10K base resistor you are not driving the 2N2222 into saturation, when you have two relay coils in parallel.

Whats the supply voltage to the relays and what is the coil resistance?

Eric

 

Do you have the mandatory free-wheel diode connected in reverse parallel?

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The relay might be a honking huge one for switching on a winch. The poor little 2N2222 will curl up and die.

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Well we are lacking almost all information!

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pretty much, he has thrown a circuit at us, and is asking how to avoid using a relay, because he doesn't have one. wouldn't you think if the circuit COULD use transistors, they would, since transistors are much faster, and sometimes more reliable???
just buy or find a relay somewhere, they would only be a couple of bucks, and it would save you all this trouble

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Those diodes are protection from the relay right?

 

Connect a 9V relay to a 9V battery. Then hold the relay's wires in one hand and disconnect the battery. You will feel a big shock (don't use both hands or it might kill you).

The voltage when the relay is disconnected might be hundreds of volts that could destroy a driver transistor. Adding a reversed diode across rhe coil clamps the voltage spike to 0.7V more than the positive supply voltage.

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