I'd like to use a single 5V digital pin to control both colors of a 2 color common cathode LED. When the pin is high and on output I want the green LED lit. When it's on input the red should be lit. Have I achieved that with this design? [Status LED] And can I delete D1? This is based on the digital pin providing a ground for Q1. I've never tried to use a pin like that before and I'm not sure it it will work.

[image] alto777: I didn't even try to make sense of the original. A novel circuit, but upside down and using a PNP transistor WTF is this doing and would it even work? Yes! and that is better. I presented NPN(N-ch) first, but later realized that the PNP(P-ch) was better. As already changed, the final simulator circuit has been modified that way. Please see this post. [image] 2 or 3 LED colors on a single digital pin General Electronics @er_name_not_found I remembered (wired-OR) that if I pressing the button, 5V was output even if digitalWrite was LOW, so I update the simulator circuit according to the actual situation. EDIT: Changed to P-MOS and reduced unnecessary current consumption.

[image] LarryD: SMD LEDs Haven't messed with smd much. I just got a bunch of SOT23 P-MOSes yesterday, they are a lot smaller than I expected. My hands shake a bit from nerve damage so I probably can do that by hand but I do have a mechanical arm project that I can adapt to apply the solder past and set the components for me.

Do you have a heat-gun like the one on the rework station? It makes SMD soldering easy. I sometimes feel big even with SOT-23... :grin:

Indeed [20210820_112459] I think it's a decent setup for an amateur. I usually use stencils for mounting chips, but they are bigger and I can tape them down.

Are there solder stencils for lots of components? Like a semi-universal set, because that would help a lot.

Looks very similar to mine! :rofl: LMAO [image]

The anti hand shake clamp is the cure for this. ;) [image] Share tips you have come across General Electronics For such jobs I've normally used solder paste, hotplate, and a hot air gun. Works well. Alan [C] [D] [D] [image] BTW You can use core bits to cut pads manually then solder SMDs to these pads. [image] Share tips you have come across General Electronics Reviewing how to make a semi permanent prototyping PCB using coring bits. In this case ‘Thin Wall’ 9mm, 6.5mm and 5mm jewelry diamond coring bits are used to make the PCB pads. It is important to spend the time to make a paper layout from the circuit schematic. A 1:1 image of the layout is made using your favorite vector drawing program. Make center punch marks on the copper clad PCB for each pad. To prevent the board from moving on the drill press, place a silicone nonslip pad under the PC… [image] Share tips you have come across General Electronics A jig to aid in making core bit pads. The ‘Core Bit Drilling Jig’ makes drilling pads in copper clad PCB material quick and easy. Attached images show all the materials needed and the use of the jig. Your 'work' is sandwiched between a drilling template and sandpaper. The jig holds the ‘work piece’ secure while drilling the circuit pads. Silicon carbide sandpaper bites into the ‘work’ so it does not move. Light downward pressure on the drilling template is all that is needed to hold the ‘… [image] [image] [image] [image] [image] Also [image] Share tips you have come across General Electronics While doing some lapidary work, it became obvious the bits I was using could be repurposed into the electronics area. Wet/dry ‘Diamond Core Bits’ are used in making jewelry and in cutting holes in glass; for example making a hole in a bottle for a power cord to go through. These bits come in many diameters and are relatively inexpensive. Core bits are hollow and nicely make solder pad shapes in PCB FR4 material. The following discussion shows how these bits can be used to manufacture a point … [image]

Minus all the crap I can never seem to clean off my bench

[image] I like laser printer toner transfer PCB etching. Well, it's mainly prototypes and funny experimental circuits. Eventually, we will place an order with a Chinese PCB manufacturer.

I've seen a lot of different techniques, that's one of the cooler ones. I love the idea of set and forget that the CNC offers and it gets me halfway to real production capabilities.

The anti-shake clamps are awesome. I use extra hands with a magnifier and I've got a 4 post extra hands table, but no surface clamp. I can make that, no problem. I like the round soldering pads for quick board prototyping. A quick step past breadboarding. Usually I use these: [20210820_115149] They make the breadboard to PCB transition so much easier for me.

2 or 3 LED colors on a single digital pin

Other Hardware General Electronics

LarryD August 20, 2021, 3:30pm 101

The anti hand shake clamp is the cure for this.
;)

BTW
You can use core bits to cut pads manually then solder SMDs to these pads.

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2 or 3 LED colors on a single digital pin

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