Knight dash project.

[JKnightandKARR]

I am going to move all information related to this project from Zappbots to here on this project, but if I remember, Chris, this is your diagram, yes?

I want to take one of the Q1/Q3 and put a PNP transistor in its place with Green_EN & Red_EN connected together to a single pin with this schematic, ex from PPDB button/switch

obviously no buttons/switch, but what goes to the mcu on the board, set to input, and buttons to the Q1/Q3 or something to that effect, lol to keep KITT on by default and KARR only when voltage is applied to the terminal.

Will post more stuff, as I can.

[Chris Savage]

I am going to move all information related to this project from Zappbots to here on this project, but if I remember, Chris, this is your diagram, yes?

Yep. Looks like something I did. 

I want to take one of the Q1/Q3 and put a PNP transistor in its place with Green_EN & Red_EN connected together to a single pin with this schematic, ex from PPDB button/switch
obviously no buttons/switch, but what goes to the mcu on the board, set to input, and buttons to the Q1/Q3 or something to that effect, lol to keep KITT on by default and KARR only when voltage is applied to the terminal.

Soooo, I am a bit confused.  All you need to do if you want the default color to be GREEN is to tie the RED_EN to the collector of Q1 and when the input to GREEN_EN is HIGH, GREEN is ON, and when LOW, RED is ON. Unless I misunderstand you. 

P.S. - Q2 / Q4 need to be able to handle the current of all LEDs (of that color) being on at once.

[JKnightandKARR]

Soooo, I am a bit confused.  All you need to do if you want the default color to be GREEN is to tie the RED_EN to the collector of Q1 and when the input to GREEN_EN is HIGH, GREEN is ON, and when LOW, RED is ON. Unless I misunderstand you. 

P.S. - Q2 / Q4 need to be able to handle the current of all LEDs (of that color) being on at once.

Basically, when the terminal is low, the PNP turns on n the KITT display turns on, while KARR is off, and when termimal is high, the opposite is true.

[Chris Savage]

Basically, when the terminal is low, the PNP turns on n the KITT display turns on, while KARR is off, and when termimal is high, the opposite is true.

Okay, so connect your control signal to RED_EN and connect the GREEN_EN to the collector of Q3.

Game, set, match. 

No PNP needed.

[JKnightandKARR]

Basically, when the terminal is low, the PNP turns on n the KITT display turns on, while KARR is off, and when termimal is high, the opposite is true.

Okay, so connect your control signal to RED_EN and connect the GREEN_EN to the collector of Q3.

Game, set, match. 

No PNP needed.

but don't that mean 2 pins to use?

[Chris Savage]

but don't that mean 2 pins to use?

Why? Your one pin is connected to the RED_EN. The GREEN_EN is controlled by the RED_EN (INVERTED). One pin does both. When LOW, the LEDs are GREEN, when HIGH, the LEDs are RED.

[JKnightandKARR]

Like dis??

[Chris Savage]

Like dis??

Yes. Now when the control signal is LOW, the RED LEDs will be OFF. However, R4 should be enough to enable Q1, which will turn ON (turning on the GREEN LEDs). Using the system in this way may or may not prompt some minor changes, such as removing R1, since you're not directly driving the transistor and changing R4 to 4.7K. Again, these changes may not need to be made, but I don't have SPICE installed on this PC to see the effects of the changes. Logically, they would seem to work without adding any new parts.

[Chris Savage]

By the way, if you're going to be feeding an audio signal directly into the input to the LM3914, I would first run it through an op-amp and then through a diode, followed by a resistor / capacitor in parallel with the signal to buffer it slightly to make it look more responsive.

[JKnightandKARR]

Got it thanks!

[Chris Savage]

Got it thanks!

I will get you the details for that soon. I would normally point you to my Audio Level Meters, but I need to first recreate the schematic (it's missing).

[JKnightandKARR]

Ok, i do have one myself btw

[Chris Savage]

Ok, i do have one myself btw

Have one what?

[JKnightandKARR]

Schematic for audio meter.

[Chris Savage]

Schematic for audio meter.

Oh. Well, I remember when I was younger building the "VU Meters" circuit right from the dayasheet. I remember thinking to myself that the response was horrible and didn't look anything like the VU meters on my audio equipment. So I designed my own buffer that I always use so the meters flow better. Anyway, that's all I meant. But if you have something you're happy with, definitely use that. Once I rebuild mine, I will be posting a video of them in action.

As a note, since the LM391x parts are obsolete now, it really doesn't make much difference. It's not feasible to think they could be used for mass production.