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Topic: Driving 12v SevSeg from Arduino 5v (Read 756 times) previous topic - next topic

islarky88

hi guys, i'm having problems with driving the 12v SevSeg (10pin sevseg. 3pin for digit[cathode] 7pin for segments[anode]

I'm currently using this library https://github.com/DeanIsMe/SevSeg

and was able to do it small scale

both are common cathode and i'm having problem with driving the 12v SevSeg

1. do i need some kind of drivers for this?
2. can i just use a NPN transistor on the segment pins and PNP on the digit pins



Grumpy_Mike

1) yes, without you will damage your Arduino.

2) It top switching 12v you need both. If bottom switching you need just an NPN. For example if you have a common anode just connect it to 12 V with the cathode connected to the resistor and then to the collector, emitter to ground and base through a resistor to Arduino output.

islarky88

1) yes, without you will damage your Arduino.

2) It top switching 12v you need both. If bottom switching you need just an NPN. For example if you have a common anode just connect it to 12 V with the cathode connected to the resistor and then to the collector, emitter to ground and base through a resistor to Arduino output.
Thank you kind sir.. can you guide me to a driver so i can do my research and test on it.. I'm kinda new to electronics... thank you so much

Grumpy_Mike

Only if you can tell me what sort of seven segment display you have? Is it common cathode or common anode?

islarky88

@Grumpy_Mike

It's a 12v sevseg common cathode.. i tested by directly connecting the segment pins to positive and a digit pin to negative.

Grumpy_Mike

#5
Dec 05, 2017, 02:21 pm Last Edit: Dec 05, 2017, 02:55 pm by Grumpy_Mike
Quote
i tested by directly connecting the segment pins to positive and a digit pin to negative.
Don't do that you will damage your digital pin as it puts 12 V on it when it is off which is way over the Vcc + 0.5V limit.

Quote
It's a 12v sevseg common cathode.
That is probably the worst way round. You need an NPN and PNP to drive each segment.


islarky88

Don't do that you will damage your digital pin as it puts 12 V on it when it is off which is way over the Vcc + 0.5V limit.

That is probably the worst way round. You need an NPN and PNP to drive each segment.


i hooked it to a 12v power supply. hehe. thanks for this mike... i learned something new today.

and out of curiosity, how should i connect things with a common anode 12v sevseg?

Grumpy_Mike

Quote
how should i connect things with a common anode 12v sevseg?
The same almost. The single NPN pulls down the segments and the segment driver circuit is connected to the common anode.

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