OK, so far so good. We seem to be on track as far as the controller goes. Unless you have a reason against, I'd still plan on putting the Red LEDs on one leg, Green on another, and Blue on another. If you go with transistor type current regulators (as opposed to simple resistors) you should be able to use that wall wart (12VDC@2A) you were looking at.

I'm not against it, that's what I was planning on doing, so I can control the separate colors for a coloring mixing effect with the potentiometers.

I wouldn't worry too much about some of the discussion between Bernard and I about the final layout of the schematics.

Honestly, while everyone was going back and forth, I got lost somewhere.

One advantage of having 3 LEDs per leg is it takes the heat off the transistors nicely, which is good.

I agree on this, and it will help make the wiring a little easier in the long run.

Do you have a source for low ohmage resistors? Locally I can 1-10 ohms in the standard values at ¼W.

In my town, no, maybe Ft. worth, but I would have no clue where to begin looking at. The only place that I know that might have them would be Mouser Electronics.

Where do you get yours from, Bill?

 

Tanner's Electroics, in Carrolton. It's a real candy store. Are you in the Dallas/Ft Worth area? I'm in Garland, myself.

Do you have driver transistors yet? I thought of something that might work better, reason I ask.

 

Tanner's Electroics, in Carrolton. It's a real candy store. Are you in the Dallas/Ft Worth area? I'm in Garland, myself.

Do you have driver transistors yet? I thought of something that might work better, reason I ask.

Im close to ft worth a small town called azle.

I dont have any components yet, im trying to catch up on a few bills atm. But hopefuul some time this week or early next week

 

Bill, is a Sziklai pair available in a single package ? It looks like your latest schematic[ pg. 44 ] has all bases covered.

 

I've redrawn it.

I would go with the one with the extra diodes CR3-6. Szikla pairs don't come in common packages as far as I know. At saturation they drop 0.6V C-E, same as Darlingtons, but they only have the 0.6V B-E drop. R1, 7, and 13 set minimum value of the current, I would test select R4-6, R9-11, and R14-16 for the max values. I use 0.65V as the max from emitter to ground resistance to figure the current rating. The first schematic was calculated for 0.5A, and the second for 0.35A (1.2Ω and 1.8Ω respectively). CR1 and CR2 make a crude voltage regulator.

 

thank you, as soon as I get the parts, and start that desk, I will start building the circuit.

If I run into any problems, I'll be back!

 

I've redrawn it.

I would go with the one with the extra diodes CR3-6. Szikla pairs don't come in common packages as far as I know. At saturation they drop 0.6V C-E, same as Darlingtons, but they only have the 0.6V B-E drop. R1, 7, and 13 set minimum value of the current, I would test select R4-6, R9-11, and R14-16 for the max values. I use 0.65V as the max from emitter to ground resistance to figure the current rating. The first schematic was calculated for 0.5A, and the second for 0.35A (1.2Ω and 1.8Ω respectively). CR1 and CR2 make a crude voltage regulator.

What do i use for q1,3,5 and q2,4,6?

 

Any low power transistor, such as 2N2222 or a 2N4401. Can be bought anywhere, including Radio Shack (in bulk packs no less).

They are there to boost the gain of the circuit, so the loading on the front end is minimal.

Looking at it the power transistors Q2, 4, and 6 are also none critical. I would plan on a heat sink, but the truth is they won't get that hot (plan on some heat and fans, just for worst case). I would select any PNP power transistor (not Darlington) you can find. If they drop 3V at 350ma they will dissipate just over a watt, which is pretty hot in a stand alone package. It depends on your power supply, they could get a little warmer, but most times they will be less than that.

You going to Tanner's? I'll be at the 3rd Saturday Sale off Woodall Rogers Freeway and Field street, under the overpass, then I usually go to Tanner's around noon.

 

Thanks for the info. Yeah ill check tanners out some time, though it will be a monday or tuesday i work weekends. Its pretty hard for me to get them off.

Im replying on my iphone so when i get a chance ill find more info on that sale thing. It will be a few weeks before i can go to tanners gotta wait til next paycheck lol

 

I understand odd shifts. I'm a 3rd shifter, 10PM to 7AM.

 

I understand odd shifts. I'm a 3rd shifter, 10PM to 7AM.

I usually work from 10 am to 10 pm everyday, it sucks but it pays the bills barely!