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drive to relay12 pieces by 1 input from 8951 using uln2003

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An 8951 output port typically cannot drive a single ULN2003 input to high (VOH=VIH), let alone 12 inputs.
You'll need a buffer in between.
 

Li_ereunpisan said:
what if the picture?
Click to expand...
No, won't work. You need 12mA high drive (from +5V to the 12 inputs).

Li_ereunpisan said:
or you have other recommendations?
Click to expand...
You could use Q1 as emitter-follower: Collector to +5V, emitter to the 12 inputs. And so you don't need to take care of the logic inversion by the transistor (an emitter-follower doesn't invert the logic state, your above circuit does).

Don't connect input pins#1 if you don't use their outputs.

Each relay shouldn't need more than 80mA (max. current of one ULN2003 ≦ 500mA).
 

Why do you want to turn on so many relays simultaneously? Why use so many switches when a single MOSFET would do the job?

Keith
 
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Your diodes are also backwards. How much current and voltage do you need to switch?
 
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Li_ereunpisan said:
what if the picture?

or you have other recommendations?

thx
Click to expand...

Your second version with NPN driver needs a pull-up resistor, diodes need to be reversed and then it will work .. see attached picture ..
As an alternative consider single MOSFET or NPN that can drive all relays connected in parallel (see Keith's thread) ..

:wink:
IanP
 

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  • 8051 and 12 rlys and NPN, added 390 and Ds-reversed.png
    8051 and 12 rlys and NPN, added 390 and Ds-reversed.png
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erikl said:
No, won't work. You need 12mA high drive (from +5V to the 12 inputs).


You could use Q1 as emitter-follower: Collector to +5V, emitter to the 12 inputs. And so you don't need to take care of the logic inversion by the transistor (an emitter-follower doesn't invert the logic state, your above circuit does).

Don't connect input pins#1 if you don't use their outputs.

Each relay shouldn't need more than 80mA (max. current of one ULN2003 ≦ 500mA).
Click to expand...
if you mean like this



keith1200rs said:
Why do you want to turn on so many relays simultaneously? Why use so many switches when a single MOSFET would do the job?

Keith
Click to expand...

I want to switc telephone line as much as 12 line simultaneously, it is certainly among one another should not be any connection

DeLorean said:
Your diodes are also backwards. How much current and voltage do you need to switch?
Click to expand...
I use a diode for reverse current protection, and the switch voltage is 48Vdc

IanP said:
Your second version with NPN driver needs a pull-up resistor, diodes need to be reversed and then it will work .. see attached picture ..
As an alternative consider single MOSFET or NPN that can drive all relays connected in parallel (see Keith's thread) ..

:wink:
IanP
Click to expand...

do you think also like the picture above?
if using a mosfet, how to swicht on it with a 5V supply







thx for all
 

The diodes are of course needed . Even the pull up resistors , why dont you try out the npn transistor solution ?
 

:pH said:
The diodes are of course needed . Even the pull up resistors , why dont you try out the npn transistor solution ?
Click to expand...

because the input is used for switching the transistor is active high,,,,
Do you have a way lain.selain menngunakan npn transistor?

erikl said:
Yes, I think this should work.
Click to expand...

ok I'll try it, but I will be simulated duludi proteus, the problem is why the lib ULN 2003 0r 2803 or2004 not work in proteus
 

:pH said:
The diodes are of course needed.
Click to expand...
Not necessarily: The ULN2003 has built-in diodes for each channel, strong enough for the permitted currents.
 

erikl said:
Not necessarily: The ULN2003 has built-in diodes for each channel, strong enough for the permitted currents.
Click to expand...

yes of course , how did i forget that ? thanks for reminding
 

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