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Topic: TIP147 with arduino (Read 5684 times) previous topic - next topic

eliasojala1234

Hi!

I bought TIP147 and wanted to control 100 Watt halogen with it and arduino. I tried that but it didn't work. My halogen was on all the time. I looked TIP147 datasheet but I'm not sure why it don't work with arduino. So why it don't work?

Thanks
Elias Ojala

Grumpy_Mike

How on earth can any one tell you that when you have not said how you wired it up.

My guess is that you wired it up wrong.

eliasojala1234

I checked wiring many times. But here is it:

left pin to arduino pwm pin
center pin to halogen
right pin to arduino gnd and power supply gnd

halogen other pin (or wire) to power supply +
Elias Ojala

Grumpy_Mike

OK stop right there.
No base resistor from the arduino to transistor. = fried arduino pin.

What voltage are you running it off?
I am going to assume you have a 5V external supply.
However, if it is 100W then the current rating is too small.

Quote
center pin to halogen

OK
Quote
right pin to arduino gnd and power supply gnd

Wrong right pin to halogen supply +ve

Other end of halogen to ground / arduino ground / halogen supply ground

This is a PNP transistor not an NPN one so it must be used as a top switch.
If there is a supply greater than 5V then you need another NPN transistor to pull up the base signal for this one.

eliasojala1234

I have 12 volts external power supply and arduino gets power from usb.
Elias Ojala

Grumpy_Mike

I think you needed to get a TIP 142 not the transistor you have. You still need the base resistor as well though.

With 12V you need another NPN transistor to drive the base up to 12V in order to turn it off.

However with a 100W 12V load you have a current of 8 Amps which is far too high for this transistor, not from the current rating point of view but the dissipation of the transistor. It has a Vsat of 3V, so with a current of 8.3 A you have power dissipation inside the transistor of 25 Watts. Now given that you can have a soldering iron rated at 25W you are going to need some very good cooling on the transistor.

eliasojala1234

How I have to wire up all the system? Can you draw me a picture? (Maybe fritzing?)
Elias Ojala

CrossRoads

Need NPN to drive PNP on "High Side" of load.
NPN lets PNP base go to 12V to be turned off.
Observe current capabilities of the transistor as noted.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

eliasojala1234

Is this good? http://arduino.3owl.com/npnpnp_bb.png

Which resistors I have use?
Elias Ojala

CrossRoads

Here's a great writeup
http://www.w9xt.com/page_microdesign_pt12_hv_pnp_switching.html

As far as connections, you have to read the datasheet and decide if you have the Base-Emitter-Collector connections correct.
Your drawing looks  like a decent start - you are missing the Arduino-NPN base transistor.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Maybe this drawing will help more.
Find the NPN you are using and make it match.
I picked this particular NPN because it only needs 10mA of current into the base to control 500mA thru the collector.
When it does the emitter will be ~ 0.03V

The TIP147 needs 40mA out of its base to control 10A thru the collector. If R1 is 10K, then when the NPN is turned on nearly all current will flow from PNP emitter to base and then thru the NPN. R2 limits that current. If we want the base of the PNP to be about 0.7V when the NPN turns on, then there will (0.7V - 0.03V) volts across R2.
Solving for 40mA thru R2: (0.7V - 0.03V)/0.04A = 16.75 ohm, so use a 15 ohm resistor there.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

eliasojala1234

How many ohms R3 have to be? And can I use TIP147 without heat sink?
Elias Ojala

eliasojala1234

Is this right?
Elias Ojala

Grumpy_Mike

Quote
And can I use TIP147 without heat sink?

Only if you are happy for it to have a life of about 10 seconds.
It is not possible to get a heat sink big enough for this load.

CrossRoads

R3, 220 ohm should work ok.
(5-0.7)/220 = 20mA.

Can't seem to be able to open .pdf's in the forum - adobe says they're corrupted.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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