Will this circuit work and do what I want it too.

[cygnos36]

The transistor blew without the 80ohms resistor, and it is stopping the current feeding them, it's power source comes through the transistor, and when there is a power source going to its base the inverted circuit power flows to ground. Need to have a selectable point for ground because the way the chip is set up, you just have the ground point for all the LED's you want to control connected to a point on the chip, I was told that if I'm using an inverted circuit I should stop it being connected to the controller (going to a ground point on the motherboard instead of grounding via the chip).

 

[cygnos36]

Does anyone want me to send the circuit so they can mess about with it an see what I mean?

 

[cygnos36]

Just tried removing the 80ohms resistor and the transistor and all the LEDs blew

 

[Hero999]

As long as you're happy I say go for it.

I'm sure it's probably no the most efficient way of doing what you want but if it works then that's all that matters.

You'll need to substitute the non-standard values 60R and 80R with standard values, 62R and 82R respectively.

Make sure you choose adequately rated components, the 82R resistors will need to be rated to at least 2W, don't use 1/W or 1/2W because they will smoke and burn. I haven't gone round the circuit and calculated the power dissipation of the other resistors, I suggest you do.

 

[cygnos36]

ok I'll get on it and hopefully get the stuff soon. Yet again thanks a lot for the help and I'm sure I'll be back on if I run into problems.

 

[audioguru]

You have 80 ohms powering many LEDs then you use the transistor to short ythe LEDs to turn them off. That is backwards.
Maybe when you removed the 80 ohm resistors then you replaced them with shorts. No wonder the parts blew up.

Usually the power is appied to something to turn it on then the power is removed to turn it off, it is not shorted to turn it off.

Your circuits have extra switch contacts switching the ground that does not need to be switched.

 

[cygnos36]

Look audioguru, I'm not meaning to sound rude or condescending because I don't have a leg to stand on, but do you know what I want this circuit to do? How would you propose I set it up if you think this is the wrong way to go about it?

Just to make sure, the reason I'm using a transistor to short its power source to ground when the inverted circuit is selected (therefore removing it's power source because that circuit feeds the LED's power. And its power source is removed in the presence of a low charge from the base pin), is because I want that circuit to go off when the circuit that is connected to it's base goes on. So as the main controlling circuit fades out via an LED controller, the other fades in. Also the reason there seems to be 2 outputs from each dpdt which go to ground, is because one isn't ground. The way the LED controller works, you just put the ground wires from any circuit of LEDs you want to control to a point on the chip, which in turn connects to ground. Now if I'm having a circuit which is inverted by the circuit connected to the controller, I'm pretty sure (along with the admins from a forum that made this chip, though strangely they haven't had to think of this use before) that it would mess with the operation of the inverted circuit. So one ground point is actually a mosfet led controller (the gnd point that all 3 circuits are connected too). I'm using an npn transistor to remove the power supply from the LED's by shunting it to ground before it touches the LEDS (removing its source just like you said). Also I believe if you have a 12v source flowing straight into a low power npn transistor the only result will be a lot of smoke (hence the 80ohms resistor). It's essentially 3 separate circuits 1 controlled by the chip, connected to all the sets of LEDs, and 2 circuits for each of the secondary sets, which are directly controlled by the first through an inverter. And the dpdt switches the power source and ground points together. Without complicated mosfet controllers which is overkill for this circuit (and I wouldn't know how to set them up) I can't see any other simple way of doing it with any less parts. If you have any problems or dislikes of the way I'm doing it, or can simplify it to use less parts then please offer a constructive design or an idea to replace it with. But it seems to be doing exactly what I want in a circuit simulator.... every part has a function.So what's the problem?

 

[audioguru]

the reason I'm using a transistor to short its power source to ground when the inverted circuit is selected (therefore removing it's power source because that circuit feeds the LED's power.

It is stupid to short the power source to ground with an NPN transistor instead of simply disconnecting the power source with a PNP transistor.
When your NPN transistor turns on its current is 12V/80 ohms= 150mA. The power that is wasted in the 80 ohms resistor is 1.8W.

In your home do the light switches short the lights to turn them off? What about the smoke that will be created? Who will pay for the tremendous amount of power that will be wasted?

 

[cygnos36]

It is stupid to short the power source to ground with an NPN transistor instead of simply disconnecting the power source with a PNP transistor.
When your NPN transistor turns on its current is 12V/80 ohms= 150mA. The power that is wasted in the 80 ohms resistor is 1.8W.

In your home do the light switches short the lights to turn them off? What about the smoke that will be created? Who will pay for the tremendous amount of power that will be wasted?

Ok, could you give me an example please, how would I do it with this circuit, and would the end result turn the inverted circuit on when the other circuit is off?

 

[cygnos36]

Ok I've just looked up the function of a pnp transistor as a switch, and don't believe it would be appropriate. Correct me if I'm wrong, but it seems it routes power from collector to emitter in the presence of a small charge from it's base. So that would mean when the blue LED circuit is on it would switch the inverted circuit on? Exactly what I don't need, I can't see how I can use that. I need a small charge from the circuits base to turn the circuit off. I'm pretty sure I've got it the right way round. If I'm wrong could you please explain how? The reason it's shorting is that's the only way for this circuit to do what I need it too. Also in my home I don't want certain light bulbs to turn on automatically if another light bulb is turned off, or I'd need a similar circuit to do that too. And I believe it will be me paying for the wasted power thank you.

Google NPN transistor as a not gate.

I believe your idea would only work if I needed to re route power if another circuit is also active not inactive.

I've seen this model for an npn inverter from quite a few sites. It seems to be a well used idea. If you know some way of turning the inverted circuit off while the other circuit is on, by using some sort of automatic switch (something I don't need to manually change) that will cut the power rather than diverting it to ground, I'm all ears.

A pnp transistor can't be an inverter, just a switch.
http://www.mayothi.com/transistors.html

A switching npn transistor seems to be the only way to make an inverter with a transistor!
http://www.kpsec.freeuk.com/trancirc.htm

 

[audioguru]

Don't short circuit the LEDs to turn them off. Simply use a PNP transistor that will turn them off when the input voltage is high like this.
Your 60 ohm resistors will need their value increased a little.

 

[cygnos36]

Your missing the point, I need to turn the LED's on when there is no input whatsoever, and turn it off when there is an input. When a PNP transistor has no input the switch is off. As I said its a switch not an inverter. The LEDs on the inverted circuit would still be on when the input is high or low, its either on (with an input to it's base) or off (without an input to its base) I need it so the inverted circuit is on when there is no charge to the base whatsoever and off when there is an charge to its base.

 

[audioguru]

Your circuit does not show an input. It shows the input to the 3k base resistor shorted to +12V to turn on the NPN transistor that short-circuits the LEDs to turn them off.
My circuit also has the 3k base resistor shorted to +12V to turn off the PNP transistor then the LEDs do not turn on.

The LEDs in yours and my circuits turn on when the input to the 3k resistor is grounded.

 

[Roff]

Your missing the point, I need to turn the LED's on when there is no input whatsoever, and turn it off when there is an input. When a PNP transistor has no input the switch is off. As I said its a switch not an inverter. The LEDs on the inverted circuit would still be on when the input is high or low, its either on (with an input to it's base) or off (without an input to its base) I need it so the inverted circuit is on when there is no charge to the base whatsoever and off when there is an charge to its base.

Are you saying that the input is sometimes totally disconnected? Is this input, when it is present, coming from your controller? If so, I think you can use PNPs instead of NPNs. I'll show you what I mean after you answer the question.
BTW, PNPs can be inverters.

 

[cygnos36]

no I don't think it's totally disconnected, just really low, in fact I don't really know, I'll look up the schematics for the chip then could one of you have a look please. If it can be used as an inverter that would seem to be a much more sensible idea. I'll brb with a link

 

[cygnos36]

SICKmods : PulseVU > Build It
Its the 2x version

 

[cygnos36]

so that's the chip, it's primary function is to pulse the LEDs to the analogue audio signal while music is playing, then it has I think 7 different pulse settings while not playing music. This is from the installation notes

Your PulseVU 2X can support up to 3Amps of LEDs, which is about 150 LEDs. To connect them to the PulseVU, simply power them with the Xbox360 and connect the cathode (negative) side of the LEDs to the VU pad of the PulseVU. Use the appropriate resistor(s) if necessary. A good +5V power source for your LEDs is the side of this capacitor, located on the top side of your motherboard.

If you require more than 150 LEDs, you can connect one or more of our Power Extenders to the PulseVU, which will allow you to control as many LEDs as the power supply can handle.

 

[audioguru]

The Mosfets on the circuit do everything. They why did you add NPN transistors?

 

[cygnos36]

The Mosfets on the circuit do everything. They why did you add NPN transistors?

ahh this is going round in circles
I'm having each LED on it's own circuit connected to the pulse chip. Blue's the main colour. The other two (purple and red) can either be on (controlled by the pulse), off (the dpdt's will be centre off) or inverted, so I can have one or both of the red and purple so they fade in when the blue fades out. So they need an inverter circuit (1 for each colour) controlled by the blue circuit being on or off and need to be able to have their input switched from the pulse circuit, and the ground point switched at the same time (via dpdt) to a normal ground point.

 

[cygnos36]

look the circuit I designed works, its been proven to work but just as an inverted circuit in a nintendo ds (but that circuit wasn't switchable). The changes I've made to the thing I saw and liked and wanted to copy were the normal input from the same power source which is connected to the main circuit controlling the inverted circuit, and the connection to the pulse vu which can be switched to the inverted circuit via the dpdt switch. Is there a more efficient way of doing it with a PNP transistor instead of NPN cos I'm pretty sure I've re worded the same piece of information like 10 times now. Apart from it's inefficiency this was the design the admins of the forum for the chips tech support advised him to do. Which is why I was so reluctant to try a design with a pnp. But if a pnp will do the same job more efficiently please please please could you tell me how cos I'm losing the will to live with this thread.