So my issue is that I am making a circuit that is able to control a light switch remotely. The items I am using are:

-Arduino Uno Rev 3

-TIP31c NPN Transistor

-PS2 wireless controller and dongle

-100W LED

-4x 9V batteries (in series)

I have used the controller and dongle before with no issue, and I am receiving commands from the controller so that is not an issue. The LED does light up when connecting the batteries directly to them so that takes care of any power issues. The arduino does do its job by sending voltage to the designated pin where the supposed base of the transistor is suppose to be. So that leaves me with the issue of whether I am wiring up the transistor wrong, or if the issue lies in another place.

The link to where I purchased the transistor is; www.amazon.com/gp/product/B01N9N1RZG/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A26TJE9XKYYNGN

The other part that may be an issue is the grounds but I am unsure, this is the schematic of the current circuit:



Should it be like this ^^



or like this^^

Another theory that I have is, if the arduino is being powered by a computer, would it be able to deliver enough voltage/current to the base to allow the electricity to flow? Any advice would be much appriciated, as I need to complete this project by March 21st, 2017. Thank you for your time!

 

Yes, the second way so the transistor's emitter connects to ground. That way base current can flow.

What limits the current to the LED? How long do you think those three 9V batteries will last? (Answer: If the LED takes 100 watts then the battery will have to supply nearly 4 amps…)

Do you intend to dim with PWM?

 

Yes, the second way so the transistor's emitter connects to ground. That way base current can flow.

What limits the current to the LED? How long do you think those three 9V batteries will last? (Answer: If the LED takes 100 watts then the battery will have to supply nearly 4 amps…)

Do you intend to dim with PWM?

Thank you, the 9V batteries do not have to last long, it is for a single performance so it will not be up for a long period of time. I do not intend to dim them with the PWM I just chose any pin on the digital side of the board and it so happened to be pwm. By an chance would you happen to know if a laptop powering the arduino would provide enough power to the base to allow the collector and the emitter to flow?

 

That's another thing (amount of base current) and I am sorry I failed to mention it.

Most likely the USB port on a laptop can provide enough current to the TIP31 for this purpose.

I worry that You will not be able to get 100 watts out of those batteries -what kind of battery are you thinking of using?

I also worry that you don't show anything to limit the current. Is the LED a lamp that is designed to run from a give voltage, or is it a bare LED?

After that you can work on the base drive needed. It might be that a MOSFEt would be a better choice, but first you need to answer the questions above.

 

That's another thing (amount of base current) and I am sorry I failed to mention it.

Most likely the USB port on a laptop can provide enough current to the TIP31 for this purpose.

I worry that You will not be able to get 100 watts out of those batteries -what kind of battery are you thinking of using?

I also worry that you don't show anything to limit the current. Is the LED a lamp that is designed to run from a give voltage, or is it a bare LED?

After that you can work on the base drive needed. It might be that a MOSFEt would be a better choice, but first you need to answer the questions above.

I am using a Panasonic 9V battery, and the LEDs are designed to run on a minimum of 36V

 

Hello,

What size of 9 Volts batteries are you using?
If it is the small PP3, the led will be lit for a few seconds.

You could have an other from the PP series.
https://en.wikipedia.org/wiki/List_of_battery_sizes

Bertus

 

Hello,

What size of 9 Volts batteries are you using?
If it is the small PP3, the led will be lit for a few seconds.

You could have an other from the PP series.
https://en.wikipedia.org/wiki/List_of_battery_sizes

Bertus

http://www.panasonic-batteries.com/eu/products/product-ranges/alkaline-batteries/power-pro

 

Hello,

Those batteries have a capacity of about 550 mAh.
https://www.battery-force.co.uk/panasonic-alkaline-pro-power-9v-6lr61-pack-of-1.html

If you led is really 100 Watts at 36 Volts, the current will be about 3 Amps.
When you are lucky, the led will burn about 10 minutes and the battery will be completely drained.

Bertus

 

Hello,

Those batteries have a capacity of about 550 mAh.
https://www.battery-force.co.uk/panasonic-alkaline-pro-power-9v-6lr61-pack-of-1.html

If you led is really 100 Watts at 36 Volts, the current will be about 3 Amps.
When you are lucky, the led will burn about 10 minutes and the battery will be completely drained.

Bertus

Thank you, I only need them to work for about 5 min anyway

 

ED a lamp that is designed to run from a give voltage, or is it a bare LED?

Hello,

Those batteries have a capacity of about 550 mAh.
https://www.battery-force.co.uk/panasonic-alkaline-pro-power-9v-6lr61-pack-of-1.html

If you led is really 100 Watts at 36 Volts, the current will be about 3 Amps.
When you are lucky, the led will burn about 10 minutes and the battery will be completely drained.

Bertus

Will the arduino powered by a separate 9v battery be able to output enough current to the base of the transistor through a digital pin?

 

Hello,

When the led is reallly taking 3 Amps, then the choosen transistor is to small.
Better look for a logic level mosfet.

Bertus

 

Hello,

When the led is reallly taking 3 Amps, then the choosen transistor is to small.
Better look for a logic level mosfet.

Bertus

I've never used a mosfet, or at least not to my knowledge, could you recommend me one that would get the job done?

 

I've never used a mosfet, or at least not to my knowledge, could you recommend me one that would get the job done?

You seem to have two threads for the same topic.
https://forum.allaboutcircuits.com/threads/led-switch-on-off-issue-with-wiring.133131/#post-1106135

 

So my issue is that I am making a circuit that is able to control a light switch remotely. The items I am using are:

-Arduino Uno Rev 3

-TIP31c NPN Transistor

-PS2 wireless controller and dongle

-100W LED

-4x 9V batteries (in series)

I have used the controller and dongle before with no issue, and I am receiving commands from the controller so that is not an issue. The LED does light up when connecting the batteries directly to them so that takes care of any power issues. The arduino does do its job by sending voltage to the designated pin where the supposed base of the transistor is suppose to be. So that leaves me with the issue of whether I am wiring up the transistor wrong, or if the issue lies in another place.

The link to where I purchased the transistor is; www.amazon.com/gp/product/B01N9N1RZG/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A26TJE9XKYYNGN

The other part that may be an issue is the grounds but I am unsure, this is the schematic of the current circuit:



Should it be like this ^^



or like this^^

Another theory that I have is, if the arduino is being powered by a computer, would it be able to deliver enough voltage/current to the base to allow the electricity to flow? Any advice would be much appriciated, as I need to complete this project by March 21st, 2017. Thank you for your time!

What kind of 9 V batteries are you using to drive the LED that can supply 3 Amps?

 

On the assumption that the OP is (now) aware of the limited run-time he is likely to get from his battery pack, the simple question is how to achieve his original stated aim.

I would suggest using a power MOSFET, like the NTD3055L170, with a current-limiting gate resistor of, say, 10K in common source mode - ie with the source connected directly to ground and the drain connected to the LED. The NTD3055L170 has a Vds max of 60V and an Ids max of 9A so it should be well able to handle the power required. And, of course, it should be connected like the second diagram, with the negative of the 36V battery connected to the ground of the Arduino.

Since the MOSFET is a voltage-operated device with a typical Vgs of just 1.7V, the output of the Arduino is more than adequate to drive it.

 

Has no one noticed that you have your transistor connected as an emitter follower?
The LED will only see whatever voltage is coming out of the arduino less the forward voltage of the emitter-base junction, so it will not be very bright!

 

You seem to have two threads for the same topic.
https://forum.allaboutcircuits.com/threads/led-switch-on-off-issue-with-wiring.133131/#post-1106135

A topic isnt constrained to one question. This is as far as I know, is a free thinking forum. Imagine if we were all sticklers for the rules,we wouldnt get anywhere, we would be continually deflecting from the topic at hand for no good reason..

 

Note that the other thread had been closed because the rule is that only one thread is allowed for each topic.