Soldering Q's

[H0R53]

I have a Rock Candy wireless controller I use for my PC. I want to solder some LED's inside. I have the LEDs.

 

There is a ground pad on the controller, which takes 2 AA batteries. If I solder the ground of the LED to the ground pad on the PCB, and then the hot wire to the + part of the battery connector, the LED will work only when the controller is on, correct? Or is the ground pad connected directly to the ground of the battery?

[VVoltor]

My guess is that way it would always be on, but you'll only know for sure by testing it yourself.

Having both + and - go through a switch would require more traces on the PCB, and is usually not necessary.

[H0R53]

3 minutes ago, VVoltor said:

My guess is that way it would always be on, but you'll only know for sure by testing it yourself.

Having both + and - go through a switch would require more traces on the PCB, and is usually not necessary.

I have the ground wire on the PCB now, I am wiring it through the shelll so I can try it. If necessary I'll solder a switch to the wires.

[H0R53]

17 minutes ago, VVoltor said:

My guess is that way it would always be on, but you'll only know for sure by testing it yourself.

Having both + and - go through a switch would require more traces on the PCB, and is usually not necessary.

Whoops, i soldered the wrong wire to ground.

[SCHISCHKA]

Don't solder onto battery when you can crimp

[mariushm]

You'll need to limit the current going into the leds unless you want them to burn up or use too much current from the batteries.

 

2 AA rechargeable batteries will give you ~ 2.2v .. 2.7v (2x1.25v) in case of rechargeable batteries, or about 2.8v .. 3.2v ( 2x1.5v ) in the case of alkaline batteries.

So if you're going to use white or blue leds that have a forward voltage of 3v or more, then they may not light up or they'll be very dim with 2.5..2.7v. 

 

For other leds like red ones that have forward voltage of 1.7v .. 1.8v and other colors have forward voltage of around 2.2v so you should limit the current in some way using a resistor in series with the led.. the formula is simple :  Input voltage - forward voltage = current x resistor

So for example if your led has 2v forward voltage and you want to limit the current to 5mA and you're going to use rechargeable batteries that give you 2.5v then :

 

2.5v - 2v = 0.005 A x r => r = 0.5v / 0.005 = 100 ohm

 

and the power wasted in the resistor would be p = i x i x r = 0.005 x 0.005 x 100 = 0.0025 watts so you can use a tiny smd resistor rated for 0.1w or even less.

[SCHISCHKA]

41 minutes ago, H0R53 said:

I have a Rock Candy wireless controller I use for my PC. I want to solder some LED's inside. I have the LEDs.

 

There is a ground pad on the controller, which takes 2 AA batteries. If I solder the ground of the LED to the ground pad on the PCB, and then the hot wire to the + part of the battery connector, the LED will work only when the controller is on, correct? Or is the ground pad connected directly to the ground of the battery?

Ground is always connected to battery. You want to connect ground but connect live end to something that is live when controller on. If it has a power led then you should connect a transistor switch to this led and use this to power you additional led

[H0R53]

23 minutes ago, SCHISCHKA said:

Ground is always connected to battery. You want to connect ground but connect live end to something that is live when controller on. If it has a power led then you should connect a transistor switch to this led and use this to power you additional led

Or I can remove the LED and use the power from it.

[H0R53]

29 minutes ago, SCHISCHKA said:

Don't solder onto battery when you can crimp

 

27 minutes ago, mariushm said:

You'll need to limit the current going into the leds unless you want them to burn up or use too much current from the batteries.

 

2 AA rechargeable batteries will give you ~ 2.2v .. 2.7v (2x1.25v) in case of rechargeable batteries, or about 2.8v .. 3.2v ( 2x1.5v ) in the case of alkaline batteries.

So if you're going to use white or blue leds that have a forward voltage of 3v or more, then they may not light up or they'll be very dim with 2.5..2.7v. 

 

For other leds like red ones that have forward voltage of 1.7v .. 1.8v and other colors have forward voltage of around 2.2v so you should limit the current in some way using a resistor in series with the led.. the formula is simple :  Input voltage - forward voltage = current x resistor

So for example if your led has 2v forward voltage and you want to limit the current to 5mA and you're going to use rechargeable batteries that give you 2.5v then :

 

2.5v - 2v = 0.005 A x r => r = 0.5v / 0.005 = 100 ohm

 

and the power wasted in the resistor would be p = i x i x r = 0.005 x 0.005 x 100 = 0.0025 watts so you can use a tiny smd resistor rated for 0.1w or even less.

 

27 minutes ago, SCHISCHKA said:

Ground is always connected to battery. You want to connect ground but connect live end to something that is live when controller on. If it has a power led then you should connect a transistor switch to this led and use this to power you additional led

They are red LEDs from an old Alienware case. They are red. There's a 3.3v pad on the PCB, can I use that?

[H0R53]

32 minutes ago, mariushm said:

You'll need to limit the current going into the leds unless you want them to burn up or use too much current from the batteries.

 

2 AA rechargeable batteries will give you ~ 2.2v .. 2.7v (2x1.25v) in case of rechargeable batteries, or about 2.8v .. 3.2v ( 2x1.5v ) in the case of alkaline batteries.

So if you're going to use white or blue leds that have a forward voltage of 3v or more, then they may not light up or they'll be very dim with 2.5..2.7v. 

 

For other leds like red ones that have forward voltage of 1.7v .. 1.8v and other colors have forward voltage of around 2.2v so you should limit the current in some way using a resistor in series with the led.. the formula is simple :  Input voltage - forward voltage = current x resistor

So for example if your led has 2v forward voltage and you want to limit the current to 5mA and you're going to use rechargeable batteries that give you 2.5v then :

 

2.5v - 2v = 0.005 A x r => r = 0.5v / 0.005 = 100 ohm

 

and the power wasted in the resistor would be p = i x i x r = 0.005 x 0.005 x 100 = 0.0025 watts so you can use a tiny smd resistor rated for 0.1w or even less.

Are the VDD pads connected directly to the battery or only used when the device is on?

[mariushm]

How should i know?

 

Take some good pictures of the circuit board and maybe we can figure out the circuit and tell you where you should solder the wires.

 

In general Vdd means the higher voltage, and Vss means lower voltage ... the [high voltage - low voltage] gives you the voltage.  So Vdd = ~ 1.5v and vss = 0 (gnd) for a single AA battery.

 

[H0R53]

7 minutes ago, mariushm said:

How should i know?

 

Take some good pictures of the circuit board and maybe we can figure out the circuit and tell you where you should solder the wires.

 

In general Vdd means the higher voltage, and Vss means lower voltage ... the [high voltage - low voltage] gives you the voltage.  So Vdd = ~ 1.5v and vss = 0 (gnd) for a single AA battery.

 

The rightmost wire is the mess I made attaching the wire. They are RGB LEDs but the red wire is actually the ground and is color coded. The white wire on the LEDs are +. The 4 resestors on the top right are on the power LEDs.

[H0R53]

I soldered the LEDs to VDD and they only turn on whent he controller is on. WOO! Will add pic in a sec

 

I did it!