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need help on energizing a 6v relay using pic16f84a

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ernestclydeachua

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hi guys i need some help here, i dont know how to use transistors but i need to know how can i make a common emitter amp to energize a 6v relay via pic16f84a's voltage output
 

Try this link..
This link about microcontroller interfacing

cq.cx/interface.pl#12
 

Switch a 100 mA, 10 V Load
The same circuit can be used for 6V application

- - - Updated - - -

You can use 6v relay in 5v supply.it's sufficient to operate.
 

ernestclydeachua said:
how can i make it 6v?
i only have 5v as my power supply
Click to expand...

That's fine: a relay works by moving a physical switch with a magnet. So the voltage required to make it switch is not directly related to the voltage and current that it can pass. For example this cheap relay on Digikey can switch a current of up to 500 mA and a voltage of up to 200V (!!). (This was just the cheapest relay I found with switching voltage of 5V - I've never used this particular product).
 

What is coil spec? If it wont work on 5V, you cant use it.
What is the load you are switching? Consider a MOSFET , BJT or a reed relay.

Relay is simple with high gain but not as fast. https://www.digikey.ca/product-detail/en/HE3621A0510/HE207-ND/133258 but good for higher voltage. This one is low current 1A, no surges.

Transistor NPN or PNP is simple but low current gain switch 10~20 for Beta.
FET is simple high transimpedance gain but need bridge to switch AC and high voltage rating costs more.

PLEASE
Define driver power and Load power to determine gain and ratings required of switch.
 

im using omi ss 206l relay 6v
5a 250vac, 28v dc

and i connect the 220vac to the NO and 110 to NC to interchange the voltage by the use of relay

and a 2N3904
 

SunnySkyguy said:
Coil 6.8Ohm = 705mA
Click to expand...
According to this:
Coil Resistance: 68 Ohms,
Coil Current: 90mA,
Coil Power: 540 mW,
which seems more reasonable.

A 2N3904 should be able to do the job, with a resistor of about 330R between it's base and the PIC output. a MOSFET would probably be better though.
 

Use relays with higher resistance in coil, that current be lower around 30-40mA. 400-600 resistance.

I think 6V relay coil will work on 5V. In some cases if you lower oltage of coil you decrease power of electromagnet and if you have bad relay contacts and higher amperage on it, maybe this can cause problem.
 

hi ,
1_1345879839.jpg

or see other posts ........
(5V can be 6V without any problem and 100 ohm -> 1K; 5 V dc relay may clamp at ~ 3.5V)
 

ernestclydeachua said:
330r to 220r
Click to expand...
The resistor should not be less than 220R. 220R may draw close to 20mA from PIC output pin, which is rated for 25mA maximum.

The resistor should not be more than 390R, otherwise the base current may be too low to saturate the transistor properly.
 

hi,
it will, i made that relley drive with 470 ohm rezistor connected in the base of a bc547 tranzistor .The relley i tested has a 5 Vdc coil . The relley clamped with 5 v supply to. (actually the relley itself clamps at 3.7 V so there is no need for the transistor to be completley saturated)
 

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