Setting diode on driver and dummy load

[chipdouglas]

this is a rkcstr driver. note where my pen is that this is the side where you connect the LD. also note that the pins (wires in my case) go on the same side.

michael

 

[chipdouglas]

now this is how to hook up a home made dummy load to a driver. note that my pen is over the 1ohm resistior that is where you put the leads of the dmm. and notice how the resistor is on the neg end of where the LD should go. also note the direction of the diodes.


edit* please excuse the mess, I am in the middle of devouring my lunch!!!!!

 

[rkcstr]

Hey, have you read the instructions posted on my site? I know they're a little out of date and I apologize, but you're welcome to ask me any questions directly about my stuff if you have questions otherwise.

One thing that I noticed that probably has confused you about the Test Load is that the resistor placement is different than the instructions (should be on the pads marked R2) and I see that you have shorted the pads it should be on. I'm sure it was the assembly instructions that had you confused since the layout isn't exactly the same. The positive and negative pads on the board are connected to the driver output, you set your range to either RED or BLU, power your driver and measure voltage across the 1 ohm resistor.

Next, for the driver, the bottom pads are simply for if you need somewhere to solder an extra pin for stability... they are not connected to anything. It looks like your positive pin is connected to the bottom, just connect it to the top (short the output pads before changing connections). The top pads are the ones you need to solder to (LD is + and GD is -). Their placement is standard configuration for most diodes (pin counterclockwise to case pin is positive, negative pin is either the case pin or the one clockwise to it), so you shouldn't have to twist anything to get it soldered.

 

[laser83]

Hey, have you read the instructions posted on my site? I know they're a little out of date and I apologize, but you're welcome to ask me any questions directly about my stuff if you have questions otherwise.

One thing that I noticed that probably has confused you about the Test Load is that the resistor placement is different than the instructions (should be on the pads marked R2) and I see that you have shorted the pads it should be on. I'm sure it was the assembly instructions that had you confused since the layout isn't exactly the same. The positive and negative pads on the board are connected to the driver output, you set your range to either RED or BLU, power your driver and measure voltage across the 1 ohm resistor.

I need to double check the instructions and the dummyload when I get home from work. Can you explain exactly what you mean by shorted?

RED as in red wavelength? Or does RED and BLU mean something else? RED is what I needed as the build uses a 5mW 625nm diode.

Next, for the driver, the bottom pads are simply for if you need somewhere to solder an extra pin for stability... they are not connected to anything. It looks like your positive pin is connected to the bottom, just connect it to the top (short the output pads before changing connections). The top pads are the ones you need to solder to (LD is + and GD is -). Their placement is standard configuration for most diodes (pin counterclockwise to case pin is positive, negative pin is either the case pin or the one clockwise to it), so you shouldn't have to twist anything to get it soldered.

Thank you, I understand now. I'll double check the instructions later but I read that as placing the pin at the bottom pad. thought the negative pin needed to be on the bottom. Had I known this soldering would have much easier using only the top pad and no worries of moving the pins. Embrassing question but what do you mean by short?
I'm going to desolder the driver and try again, and this time I can use the the test load as well.

Thanks everyone I'll have more questions when I get home.

 

[rkcstr]

Short is just a term for "low resistance electrical connection", ie touching two electrical points with something metal or connecting them with a wire, etc, which would "short it out". Typically I just use a pair of fine tipped tweezers or a flat head screwdriver to short the laser diode output contacts.

Here's a pic showing what I'm talking about with the resistor:

As for the "RED" or "BLU" connections, those are the settings on the board... see them on there? The pads directly to the right of each one are shorted (connected with a solder blob) to select that setting.

 

[laser83]

One thing that I noticed that probably has confused you about the Test Load is that the resistor placement is different than the instructions (should be on the pads marked R2) and I see that you have shorted the pads it should be on. I'm sure it was the assembly instructions that had you confused since the layout isn't exactly the same. The positive and negative pads on the board are connected to the driver output, you set your range to either RED or BLU, power your driver and measure voltage across the 1 ohm resistor.

Checking the directions again now. That's why made that error with the resistor placement; the instructions were different. The resistor was not shown to be placed in the correct spot R2 as you indicated but instead the spot I had. Looks like I have to do some more soldering. That tiny resistor was extremely difficult for me to do as you can see by the mess, the spot was not easy. The proper spot will be much easier.

Short is just a term for "low resistance electrical connection", ie touching two electrical points with something metal or connecting them with a wire, etc, which would "short it out". Typically I just use a pair of fine tipped tweezers or a flat head screwdriver to short the laser diode output contacts.

I've heard the term of course, not the same as grounding against static that's what I thought it meant. Shorting out electronics destroys them was my understanding so was unsure what you meant. That's what you meant by shorting out the pads it should be on. I'll read up on low resistance connections as I could write another thread on that term. wondering then so if a copper wire was connected from one battery to another that would be a a short? I'm trying to understand terms used, pardon my ignorance.

This isn't so bad but at the time I wanted a competed dummy load circuit and you can see why with my soldering ability. I'm glad I had to do it myself and this way as I'm learning much more. I'm a bit afraid of soldering but I've just started and I never really did it before that's why my work looks so terrible. I had done a little practice but I still apply too much solder and SMD soldering is extremely difficult even with some tips I was given by electrofreak.

The positive (or LD) lead of the diode should be soldered to the pad below the ‘LD’ marking on the driver, while the ground (or GND) lead should be connect to the pad above the ‘GD’marking. The layout of this driver is the COMMON pin layout of MOST diodes, please verify
your pin-out with a reference source for your diode before connecting the leads

I read this part wrong on soldering the diode, I thought below meant below the LD on the board not next to. The rest of the instructions explain but that part was not clear. The diode pinout layout was the common one by the way.

I'm going to clean up the soldering on the dummyload tomorrow. It as well get the driver diode soldered properly. I'll report results I should be have my working build done shortly now that I have a much better idea. At the least the I can get the dummyload working.

Thanks for the help everyone I now "think" I know what I'm doing. I have had no prior electronics training or formal education besides building PCs and that is nothing. I've had much more to learn. I think once I get over the learning curve so speak it will get easier. Now if I could figure out a good way to press the diode into the housing the axis module and I have read guides on it but still need to find something better to use.

I appreciate answering my "newbie" questions rckstr, chip, and rog. You'll see a working build shortly so I'll make up for!

 

[rkcstr]

Yeah, I'm really sorry about that. I wrote the instructions last year when I first started making these and the design has changed slightly since. Before the letter 'LD' used to be oriented so that the pad was "below" them, but they're turned 90 degrees from that now and I didn't even catch that discrepancy.

I've been meaning to fully update them to reflect the newest versions, but it takes a lot of time to take pics, write, layout.... time's been a premium lately for me, which is why I try to answer any questions when someone PMs me or posts in my 'for sale' thread.

Anyway, yeah, a short is typically bad in electronics since you're introducing a low resistance path between two things that are not supposed to have one, which ends up drawing more current than it should, creating heat and ultimately damage and destruction. Connecting two batteries with a wire could be called a "short", sure, but I don't think it's commonly used unless you're shorting out the battery by say connecting a wire from the positive to negative... lots of current, heat and probably damage to ensue.

Typically a "short" isn't a good thing, but in the case of the driver, you want to short the cap to get rid of any stored charge it has, but that isn't a condition you want during operation... in that case, it wouldn't be useful.

Anyway, my tips for SMT soldering are:
1) get a fine tipped iron that is either low watt or temp controlled.
2) get flux and some thin solder (like 0.5mm).
3) Get some fine tweezers so you can hold things without them being in the way
4) Now, how I do it is: apply flux to the pads, hold the component in place with your tweezers, get a tiny bit of solder on the tip of the iron and touch it to the pad and allow to flow to the component. With the one pad soldered, you probably won't need to hold it for the rest, so just repeat the rest of the steps.

 

[Mohrenberg]

why is the R1 resistor missing in the picture of your driver?

 

[dr-ebert]

It's not; in the top picture there's an SMD resistor, in the lower one a standard axial resistor (if you're talking about the pics in post #21).