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Help for driving large 7 segment display

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sn_burki

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Dear all,

I am making digital clock on large display, I want to use ULN 2003 and UDN 2981 ICs. I want to drive 12V display. if any one have any idea or suggestoin plz put it forward.

There is a freewheel Pin #10 on UDN 2981, What is the purpose of this pin where it is used inverse bias in most of the circuit? this pin is on ULN 2003 too and in most of the ciruit it is used inversly bias? to what is the function of this pin which is not metioned in data sheet..




regards
 
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When you're driving inductive load (relay solenoid, motor, etc..) you need to put a 'flywheel' diode across the output of your driver circuit to make sure that none of the induced electricity when your driver TURNS OFF but motor continues turning (on it's own inertia) can damage any of your sensitive components.

The flywheel diodes inside ULN2003 are all connected together to one common port (pin 9 or 16 if I remember well) and they carry the load of any inverse current that gets sent across by the inductive part.
 

jumper2high said:
When you're driving inductive load (relay solenoid, motor, etc..) you need to put a 'flywheel' diode across the output of your driver circuit to make sure that none of the induced electricity when your driver TURNS OFF but motor continues turning (on it's own inertia) can damage any of your sensitive components.

The flywheel diodes inside ULN2003 are all connected together to one common port (pin 9 or 16 if I remember well) and they carry the load of any inverse current that gets sent across by the inductive part.
Click to expand...

Thanks for you reply,
so you mean that in ULN 2003, the pin no 9 in useless in leds display, it should only be used in inductive load. If i m making a led display I should not use it????? shall i leave it open? ground it or attach it to +ve pin??? please guide me.

thanks
 

hey u didn't mention the current consumption of ur Seven Segments, ULN2003 can provide a limited current of 600ma, so be careful

if u r driving LED's directly without any Relay then there is no need for flywheel diodes to absorb inductive kicks produced by inductive loads
 

If your display requires more current you can use L293D driver which supplies upto 1A current with 4 channels.
 

Yes it can provide current not more than 600mA, if more than 600mA is required then BD136 is good solution.

I need 300mA current as I want to drive Seven Segment Display which I have made on small white murcury LEDs. and It takes 300mA current only.
 

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