Build Thread - Eggtimer Classic

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Antares JS

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I have not done much soldering but figured I knew enough to at least do an all through-hole kit.

I started with the big processor chip per the instructions. The chip fits pretty tightly. The tape was there just in case.

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Antares JS

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I have no idea what an optoisolator does, but the two of them were next. They look like smaller versions of the main processor chip. For both these and the processor chip, you need to match the notch in the chip with the notch marking on the board so you don't put them in backwards.

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SILVERFOX

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Thanks for the good pics. Need to get my next cataract surgery out of the way at the end of January before getting started on my Eggtimer builds. Do you have any favorites when it comes to soldering gear?
 

OverTheTop

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I have no idea what an optoisolator does, but the two of them were next.
Optoisolators have an LED on one side shining on a phototransitor (or something similar) on the other side. Turning on the LED turns on the transistor but there is no electrical connection between the two. That means, in our case, the pyro circuits can be separate from the microprocessor controlling them. Any ground bounce (due to high currents) or RF pickup on the long leads (aka antennas) is far less likely to affect the operation of the processor/sensor system. I don't know the circuit in detail so that's about all I can say with confidence :) . They are typically used where high voltages need to be safely controlled.
 

waltr

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Your soldering looks very good. The eggtimer should work as expected.

The surface mounted parts on the other eggtimers are not that much harder to do. I think you do have the soldering skills.
 

Antares JS

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LED's and the first resistors. Note the longer lead on the LED's needs to go in the + hole. Resistors aren't polarized but they are mounted vertically on this board as shown in the photo.

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Antares JS

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Resistors, resistors everywhere. Be careful to put the right ones in the right places. There are a good half a dozen different types.

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Antares JS

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Thanks for the good pics. Need to get my next cataract surgery out of the way at the end of January before getting started on my Eggtimer builds. Do you have any favorites when it comes to soldering gear?
No, I just got a cheap temperature-controlled soldering station with a fine tip on Amazon, some .6 mm leaded 60/40 solder as recommended by the instructions, and the helping hands that you can see in the pictures.

Your soldering looks very good. The eggtimer should work as expected.

The surface mounted parts on the other eggtimers are not that much harder to do. I think you do have the soldering skills.
Thanks, I actually did finish it in the evening and it at least starts up and is able to be programmed, but I am limited in how many pictures I can upload in a short time. I haven't had a chance yet to try actually firing an ematch with it.
 

Buckeye

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Why the vertical resistors? Space savings? Is that your trick or does Eggtimer recommend doing so?
 

T-Rex

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Very nice photos. I think I took 2 or 3 evenings to build mine, just because. I have another Rev C and 2 rev D in the build box. Since I have 2 JLCR, I may never use my eggtimers, but have them if I decide to play with true DD.
 

neil_w

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Pre-SMT, vertical resistors were a thing... if you look at older R/C receivers, virtually all of them had vertical resistors to save space.
It's really a very efficient technique, since through-hole boards normally require a good bit of vertical space anyway. And it looks cool.
 

OverTheTop

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It's really a very efficient technique, since through-hole boards normally require a good bit of vertical space anyway. And it looks cool.
Got to watch out for the bare legs shorting together in really dense layouts though.
 

DarthMuffin

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Great pictures! I finished a Quantum recently and assembling the pre-smt components on this looks like a nice vacation in comparison. (not complaining, I like small but you gotta work for it)
 

Antares JS

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I use 9V batteries, so I soldered a couple of jumpers and the voltage regulator as the instructions said. I dont think the picture in the instructions does a good job showing how to bend the center lead on the regulator, but the description and the hole pattern on the board make it easy enough to figure out.

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Antares JS

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After that, solder the transistors and the screw terminals I got for the outputs, and we're golden.

I'll post again when I get around to doing some test firings with it.

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cautery

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After that, solder the transistors and the screw terminals I got for the outputs, and we're golden.

I'll post again when I get around to doing some test firings with it.
Looks like a good job! :D

I am NOT an expert, but I WOULD like to offer you some advice from my admittedly limited experience.

1) Wash the flux off the board, especially the solder/non-component side. I use 99.9% Iso. alcohol. I repeat three times or until I can detect no residue and the alcohol evaps with no "pattern" left behind.
2) Once clean, use some type of magnification to INSPECT EACH SOLDER JOINT! You are looking for solder starvation, cold solder joints, et al. just ONE bad solder joint could result in assembly failure to function.... especially in our high vibration application.

I like to make SURE that no solder pad remains visible, that there is "plenty" of nice smooth/shiny solder (little to no concavity; shiny indicates NOT cold), and that under inspection in 10x or better mag under very strong light that I cannot see ANY "parting lines" at the terminal or pad interfaces.

I can't see any of that here, but there isn't a sufficiently detailed photo to verify it. I would do this BEFORE putting it on a rocket that I valued beyond one flight.

And.... see below....

Got to watch out for the bare legs shorting together in really dense layouts though.
In general, after I clean and inspect as above, and I make any joint corrections/reflow, etc, I wash the board down as best as is possible BOTH SIDES, and then apply conformal coating on BOTH sides of the board to avoid corrosion, et al.

This ALSO helps to avoid shorting, especially on vertical resistors, et al exposed leads, connections.

This is a NICE board design, @cerving! I love building kits.... May have to grab a bunch of yours and build them just to have them available! :D
 

OverTheTop

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If you want to improve your soldering of the thru-hole parts I might suggest you aim to get the solder filling the barrel of the hole. Many of your joints are "target condition" with the solder completely filling the hole in the PCB from the solder side to the component side. Target condition is what we are aiming for all the time. Some holes are not so lucky and the solder only goes through part of the way, from what I can see in the pics anyway. To drive the solder into the hole you need to perhaps heat for just a little longer, and make sure the wire going through is heated too. Try to judge the amount of solder you feed in to provide the requisite amount. Inspect each joint and tweak your technique as you go. Feedback works :).

Remember that solder follows three things:
  • Heat
  • Flux
  • Other solder
You can use that knowledge to get the solder to go where you need it to :).

As cautery said, a wash with flux remover or alcohol is great for being able to inspect the joints properly. I use flux remover but alcohol or metholated spirits applied and scrubbed with an old toothbrush works well (don't forget safety glasses!). Inspection with 10x magnification is recommended.
 
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cautery

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Remember that solder follows three things:
  • Heat
  • Flux
  • Other solder
Yep... And here's some more unsolicited technique/advice....

I like to use higher heat than most folks recommend... And I try to use shorter duration to compensate. That's just me.... Doing this is "risky", but you can compensate/mitigate the "risk" with techniques....

On multi-pin components, especially integrated circuits like those 8-pin and the 28 pin in this kit, but anything with a temp limit..... which is every component essentially.....

1) Make sure every pin, wire, lead is clean and tinned (usually all are except non-tinned wire). Same with the board/pads... clean, clean...
2) We aren't in production, so WE can take our time.... TAKE YOUR TIME!
3) On a multi-pin.... Solder one pin.... then solder a second pin somewhere far away from first pin. This assists in not accumulating heat inside the chip and possibly exceeding to max package temp. (Most datasheets will give you a max temp and duration for soldering.) Then take a break, or move to a different place on the board and work on another component..... but LET THE CHIP cool to ambient. Come back later, do two more pins.... repeat until complete.

4) On inspection, IF I determine that I need to reflow a joint or add solder, I ALWAYS clean and add supplemental flux first..... the flux in the core of the additional solder is often not ENOUGH..... especially when you are trying to reflow to get solder to completely fill the through-hole.

This is what I do..... Your mileage may vary.... ;) :D
 

OverTheTop

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Some good advice in the above post.

Except:
I like to use higher heat than most folks recommend... And I try to use shorter duration to compensate. That's just me.... Doing this is "risky", but you can compensate/mitigate the "risk" with techniques....
Those that subscribe to the "quick joint is a good joint" approach and using higher heat usually end up with problems of the PCB pads and traces detaching due to the adhesive and PCB substrate not being able to withstand the heat. You might be able to solder it but you might get zero reworks without damaging the PCB irreparably. High heat is not necessary. Normal leaded solder melts at 213degC, and you can solder at about 240degC with a good iron and technique if you are keen. The extra 30degC is needed to give the metals enough energy to form the intermetallic joint that provides the conductivity. I generally run around 280degC, but many would find that too difficult to get good joints with. I am lucky enough to have a good iron. I suggest no hotter than 300degC. That should provide a balance between compensating for poor technique and not being too harsh on the PCB, if you are lucky.

IMPORTANT NOTE: Cris provides LOW-TEMPERATURE solder with his kits. The temperatures I have quoted above are for standard 60/40 solder and will be well in excess of what is required for the low-temperature stuff in the Eggfinder kits. Use whatever temperature Cris recommends in his documentation when assembling those.
 
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cautery

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Some good advice in the above post.

Except: <high heat; low duration>

Those that subscribe to the "quick joint is a good joint" approach and using higher heat usually end up with problems of the PCB pads and traces detaching due to the adhesive and PCB substrate not being able to withstand the heat. You might be able to solder it but you might get zero reworks without damaging the PCB irreparably. High heat is not necessary. Normal leaded solder melts at 213degC, and you can solder at about 240degC with a good iron and technique if you are keen. The extra 30degC is needed to give the metals enough energy to form the intermetallic joint that provides the conductivity. I generally run around 280degC, but many would find that too difficult to get good joints with. I am lucky enough to have a good iron. I suggest no hotter than 300degC. That should provide a balance between compensating for poor technique and not being too harsh on the PCB, if you are lucky.
Oh! Well I guess I don't really use THAT high of heat then. I set my old RS station such that the actual temp is pretty much in the ranges you outlined.
I've never had a pad let go or any other kind of PCB degradation due to heat or duration. (I've repaired a bunch, but fortunately have not created any.) I have a decent set of irons, and as many different quality tip sizes and shapes as I can get my hands on.... ;)

"quick joint is a good joint" <----- Nope, never.... A good joint is a good joint. Good work cannot be "rushed". :)

Carry on. :D
 
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