Is a capacitor needed for TIP31C Transistor Control

I have an NPN type Tip31c transistor wired up to control a 12v load at .5 amps(max) from an Arduino Uno Pin. The load is signal amplifier for tv. There is the appropriate resistor between the transistor base and Arduino pin. The circuit works just as intended with no issues but after reading around some I discovered that maybe I should add a capacitor to help. However, i am unsure really what the capacitor does and where to add it(is between GND and the corresponding Arduino pin correct)? And what is the appropriate value for the capacitor? I have read multiple different things. I have multiple 104, 103, and 1 101 valued capacitors if needed. Thank You

Update: I am unsure of the resistor added as It is in heat shrink... multi-meter reads it as 555 ohms. The first diagram is the currently working circuit and the second is the proposed with a capacitor.

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Please show the circuit. If you are switching a load there is no need for a capacitor.

There is the appropriate resistor between the transistor base and Arduino pin

Well how can we verify that if you don't tell us what the resistor value is?

When writing a post to ask for help you need to remember that forum members have absolute no clue what you are doing. We can't look over your shoulder and see what you see. You supply only a small piece of the circuit that doesn't supply much information to help you.

If you wish to repost, sit back and consider your circuit, what is working and what is not working. I realize you are a novice at circuitry but now is a good time to start learning.

You probably don't need the cap, if as you say everything is working...

But as others have said, you need to post the schematic if you want us to be able to help...

MarkT: Please show the circuit. If you are switching a load there is no need for a capacitor.Well how can we verify that if you don't tell us what the resistor value is?

I was trying to not say the value because I forgot it and cant check without serious modification. Multi-meter reads it as 550 ohms though