2 relays as output of timer 555

[panjangsangat]

from that article, i want to know it is possible to put 2 relays or motor as ouput of 555 timer because relays itself worth 200mA and it is the maximum amount of currnet 555 timer can handle at time?

 

[Hero999]

It depends on the current requirement of the coils.

 

[Dragon Tamer]

if you're trying to drive a relay that uses a lot of current when energized, you could use transistors to boost the current capability.

 

[audioguru]

Your circuit has the 555 driving a transistor that powers the relay coil.
But the transistor is an emitter-follower that has a base-emitter voltage loss of that is about 0.8V in addition to the output high voltage loss of 1.4V so the relay coil will get 2.2V less than the supply voltage. Maybe you can use the transistor as a common-emitter circuit that has a voltage loss of only 0.3V.

Where did you find an old BFY51 transistor? They have not been made for about 40 years.

 

[Hero999]

Do you know the resistance of the relays?

Use Ohm's law to calculate the current for each relay, add the currents together, if it's >200mA then use a driver transistor in a common emitter configuration. I'll help you with that, if you need it.

 

[Dragon Tamer]

it should say right on the relay's package, how much current it draws.

 

[panjangsangat]

thanks, now I become more understand about this problem..