OK, thought it was $12 per board!18 @.72
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OK, thought it was $12 per board!18 @.72
The extra copper is $17.00OK, thought it was $12 per board!
Ive since moved components around. I needed the NPN on the side. I added this small pour from the collector to the lights output pin. The PWR track that went to the lights positive pin was not needed as this circuit is a negative (low) switch so it was removed. My question is this. The method i added the pour planes. I first added a full GND plane indicated by the 4 black arrows. then i drew a smaller pour plane in the top left and assigned to the collectors net. JUST TO BE SURE I DID THIS CORRECTLY. I could take it further and reduce the size of that track, add the pour, adjust the spokes (there will be only 1) from 12 to 20.The only place where beefy traces are needed is at the collector and emitter of the Darlington transistor, as well as the PWR input.
Emitter is probably connected to the ground plane, so that's good. But the collector track is carrying alot of current so should be wide. The PWR track from the power input (wherever that is) to the light could be a small copper plane on the top side.
I do appreciate your suggestion. Im just about to submit this for fabrication. So many have suggested using Adrunio its just a matter of time before my curiosity catches up with me. Thank you.I built a very similar PCBA for a different application. But it has 2 MOSFETs controlled by the microcontroller which is all you need.
I measured the amp draw of the LED strips using my multi meter. ive got 3 types. lowest was 1.3A. Another style was 1.8A. and the third was 2.1. Far less than the documented 4-5 amps by the seller. And that was the entire 15 foot spool. My use will be limited to 2-4 feet of leds connected to one Fader Circuit with exception of 2 being the entire reel.At 2A it will be dissipating around one and a half watts, so quite hot and may need a small heatsink.
HiIve since moved components around. I needed the NPN on the side. I added this small pour from the collector to the lights output pin. The PWR track that went to the lights positive pin was not needed as this circuit is a negative (low) switch so it was removed. My question is this. The method i added the pour planes. I first added a full GND plane indicated by the 4 black arrows. then i drew a smaller pour plane in the top left and assigned to the collectors net. JUST TO BE SURE I DID THIS CORRECTLY. I could take it further and reduce the size of that track, add the pour, adjust the spokes (there will be only 1) from 12 to 20.
I have found that its fine to draw pours over top of one another. Just to be sure they are applied in order.If the collector pin pad and the light terminal pin pad are on the same net, and they are thru hole pins, and you used a pour to connect them together on the top side, then there shouldn't be a trace between them on the top. The pour should be solid area with thermals (wide - 4-spoke thermal) located at each pad. There seems to be a red trace making the same connections but splitting the pour...
It will. I just have not applied it yet.The grounded side of the power NPN should be connected to the ground pour (top and bottom) with thermals.
Here are both pours. Top only. If i add the bottom GND pour it will be difficult to see. I resized the pad on the base pin from 70 to 65 and it was enough to get 4 spokes on the collector pin. The emitter pin has 3 spokes.The pour should be solid area with thermals (wide - 4-spoke thermal) located at each pad.
Really, there's no real reason to add more, or less, spokes than 4. Remember what you are trying to accomplish with this small pour.Ive rearranged the component to improve the number of spokes on the collector pin (2) and i have 6 on the output pin.
I did not realize that it worked that way. "Adding more spokes removes copper and increases resistance." I take it the spokes are not copper but another metal. The color being the same as the pour led me to believe they were the same hence the more spokes the better. Im glad i asked. Ill manually remove two spokes from the other pad. Reason i could not get the four on the collector pad without increasing the layout to six.Really, there's no real reason to add more, or less, spokes than 4.
That's if you are using a FET; a MOSFET will dissipate most during the PWM fade and very little while on.Now if ive understood correctly the heat dissipation is only when its fading and not while it fully on or fully off.
The spoke IS copper and are part of the pour. The "gaps" between the spokes "thermally" isolate the pad from the pour while the spokes maintain electrical conductivity between the pad and the pour. Each spoke is a "track" and passes current just like any other track. Therefore, with regard to electrical current, it has the same attributes. A thinner spoke has higher resistance and resists current flow, while a wider spoke has less resistance and will allow more current flow. You also want to keep the spokes evenly distributed around the pad so that heat is evenly distributed.I did not realize that it worked that way. "Adding more spokes removes copper and increases resistance." I take it the spokes are not copper but another metal. The color being the same as the pour led me to believe they were the same hence the more spokes the better. Im glad i asked. Ill manually remove two spokes from the other pad. Reason i could not get the four on the collector pad without increasing the layout to six.
Your correct. I narrowed the isolation gap by just 1 pt and it added all the spokes evenly around the pad.If you have time, create a small project with a PCB, place some parts and play with the pours and clearance settings. You'll see how they affect how well the pour forms around tracks, pads, and thermal reliefs. The clearance settings are very inportant to know how to use.
You are right. I left it on for a few minutes and the temp climbed 1 degree every 10 seconds.The darlington dissipation will be proportional to the LED current, so continuous while the LEDs are on.
Hi. I have crunched more number and performed a few tests. As i mentioned before the listed current draw and wattage was different from what i measured so there may be a chance i do not need the additional copper if i can widen the right tracks. Hopefully then i can avoid the $17.00 up-charge for the 2oz copper.Plus the PCB tracks need to be wide enough to handle the current; I can't remember how they ended up.
Hi. I have crunched more number and performed a few tests. As i mentioned before the listed current draw and wattage was different from what i measured so there may be a chance i do not need the additional copper if i can widen the right tracks. Hopefully then i can avoid the $17.00 up-charge for the 2oz copper.
Ive added a pour from the collector to the output pin. The shape is not a rectangle but its area equals 190 cubic mm.
Every light with exception of 2 of them draw .5amps of current. The temp of the Darlington increases 14-15 degreesF under this load. Would you agree that the darlington is good for loads under .5 amps?
The other two draw 1amp each. The darlingtom reaches 99F under this load. I personally would use a mosfet for these circuits if not to only reduce the heat dissipation but for the knowledge i have gained from your assistance. (I actually thought a FET and a mosFET were the same thing) My question for these 1amp loads is what tracks would i need to increase to meet the goal necessary?
I mean i looked up what the safe operating temp was for the darlington and 150c is not something im going to subject this circuit to.
View attachment 135585
Generically, they can be - "FET" covers all variations.I actually thought a FET and a mosFET were the same thing