[SOLVED] How to get 12 volts out of ATmega without using the same battery?

[kahraba]

Hey guys.​

I have a problem, I want to turn on some LEDs I have that uses 12volts.
I want to control them by my ATmega32, but my problem is that I won´t really use the same power source that ATmega uses because I already use two motors running by these batteries.
So is there any way to control them by ATmega32 but using another source to feed them by?



Sorry for my bad English.

 

[albert22]

Use a driver with a NPN transistor.

 

[kahraba]

You mean with two power sources, for the base and the collector?
Is that possible?

 

[tpetar]

See example:

Instead of relay and 24V you use 12V, led and led resistor, according to your needs and design.

https://www.mikroe.com/chapters/view/17/

 

[D.A.(Tony)Stewart]

Yes external car battery 9-14v can be used with a transistor driver. Best bet is use an automotive "low-side" or "high-side" switch. Single transistor stages can switch with a current gain of only 10 with rated switch low voltage drop Vce(sat).
Relays are about the same with a gain of 10 in the ratio of contact current rating/coil current rating.

When looking for power switches , remember this category...
Product Index > Integrated Circuits (ICs) > PMIC - Power Distribution Switches

Here is one of hundreds of examples.. Read the specs fully and buy a bunch. They are cheap.. <1$ but far superior to any single stage transistor and did i say cheap?

Si3861BDV
Number of Outputs 1
Rds (On) 75 mOhm
Internal Switch(s) Yes
Current Limit 2.3A
Voltage - Input 4.5 V ~ 20 V
Operating Temperature -55°C ~ 150°C
Mounting Type Surface Mount
Package / Case 6-TSOP (0.065", 1.65mm Width)

This means you can drive them from low voltage logic levels to drive 2amps easily. LED reels start around 1.2 A

 

[albert22]

You mean with two power sources, for the base and the collector?
Is that possible?

That is clear looking at the figure posted by tpetar. take into account that in that case the two supplies +5 and 24v share the same GND.

 

[kahraba]

tpetar Thank you for your help, I will go for that and will be back if I need to ask for something you are the good one.

SunnySkyguy Thank you man helpful information.

albert22 Thanks to you and yes sure the ground must be the same else no current through thank you to mention that.

Thank you guys

 

[D.A.(Tony)Stewart]

See example:

Instead of relay and 24V you use 12V, led and led resistor, according to your needs and design.

https://www.mikroe.com/chapters/view/17/

10k only drives T1 with < 0.5mA T1 only has a gain of 10 saturated maybe 20 to 50 with special components. Check specs usually Vce is rated for Ic/Ib=10
so 10k should be 150 to 500 ohm depending on desired output current.

Driver chip is more reliable. and cheaper such as high side example I gave.

 

[kahraba]

10k only drives T1 with < 0.5mA T1 only has a gain of 10 saturated maybe 20 to 50 with special components. Check specs usually Vce is rated for Ic/Ib=10
so 10k should be 150 to 500 ohm depending on desired output current.

Driver chip is more reliable. and cheaper such as high side example I gave.

This is exactly what I want!
Because the actually currents is coming from the second source. Im I right?