[WIP] 17mm DD+single-7135 driver / single sided / Dual-PWM

It also depends on the exact 7135 chip and the emitter, and even how many. Some 350mA chips work better at PWM=2, others work better at PWM=3, and the 32x7135 SRK driver lights up even at fast PWM=0. Older emitters require a higher PWM level than newer ones, usually. The highest I’ve seen was an old XM-L which needed PWM=9.

If I have an e-switch I don’t bother with specific modes. I just use a smooth ramp from moon to maximum. On a single-channel driver (or tiny25/45/85 FET+1 with a slightly different pin setup), the low end can have extra-fine adjustment by using PWM+PFM, so you can get lots of precision in the moon range instead of just a couple levels. I haven’t actually seen a driver set up with two channels on independent PWM counters though, and now I kind of want one.

Some happiness arrived in the mail yesterday. Those 0805 SMD pads look soooo tiny.
I’m ok with learning to reflow the one sided boards but how do you reflow a two sided board and not lose all the parts off of the other side?
Is it time to add a hot pencil to my soldering station ?

Surface tension of the solder is greater than gravity. They stay floating in place on their pads just fine. Unless you bump it while the solder is still liquid. A big heavy part with small pads can sometimes fall off, but that's why you do the side with heavy parts last (or hand-solder them afterwards).

Cool! 8~~) I had been wondering this for a long time as well. But, I’m not doing any re-flowing yet, so I never asked the question. O:~~)

So assuming I use a toaster oven,

  1. I would populate one side of the boards
  2. Ramp up the heat.
  3. Hold max temp till reflow is complete.
  4. Ramp down till cool.
  5. Flip over, repeat.

The other less sophisticated method that I am considering is to place the populated boards on a solid bar of copper and heat from below with a torch. Then again, maybe the copper bar would only work good to reflow LEDs.

Spend the ~$50 for a hot air station. Search Amazon for '858D'.

Hot air is so much more versatile than an oven. You can heat just one area and pluck off one component without disturbing anything else or re-melting all of the solder on the whole board. It's also easier to control the total heat input - time can be just as critical as temperature. With the board right out in the open in front of you, you can watch the paste flash over and then remove the heat right away. Hard to do that when it's inside an oven.

About fifteen years ago I bought a Weller WSR1002 Rework Station. I never purchased the hot air pencil for it. It’s dis-continued model now so I don’t know if I can find hot air pencil that will work with it. The 858D looks like a lot of tool for the money so that’s my backup plan.

I’m not personally familiar with the industry, but I believe that mass produced boards are sometimes done using two different temp solders. Neat-o.

Personally I do my reflows using a large 1500W heat gun - mine is the MHT3300. Those run about $40 and are good for other types of project. They are definitely not as flexible for soldering work as the little stations. I do own a hot air station, but never learned to get the proper use out of it. Since I’m space constrained it’s in storage, unlike most of my other soldering gear.

At the end of the day hobby reflow will probably still require skilled soldering touchup - especially as you learn the ins and outs of reflow. It’s quite possible to solder the entire boards by hand, take a look at my videos here: Nanjg stripping and A17DD-SO8 building videos

I may have to get one of those…

Any idea if it would run on a 15A 120V circuit which is already at ~30% capacity? Some reviews suggest it may need its own dedicated circuit or even a 20A circuit. Pretty big change from my weak little 40W soldering iron.

Heads-up….there may be a latent defect with that model.
Wanted to see what it looks like and one of the top google hits was this:

http://www.cpsc.gov/en/Recalls/2009/Wagner-Spray-Tech-Recalls-Heat-Guns-Due-to-Fire-and-Burn-Hazards/

This is old news from 2009 so of course YMMV, but something like this can ruin your day.

1500 W = ~12.5 A and the fan motor may also create an additional inrush current at start.

So a 15 A circuit may give you nuisance trips, especially if there are other stuff on the same circuit. You are also not supposed to load a breaker above 80% of its rating. That said, I use a 12.5 A generic to shrink sleeving and flow the occasional emitter, no issues on a 15 A circuit.

Sorry, been way behind on this, so just ordered my first set of v032 boards. I took a close look at MCU pin#3 and looks like it’s connected to a pad covered over by the solder mask, but that’s fine - easy enough to scrape off, and I no longer would have to solder a wire direct to the MCU pin.

Somewhere above it was mentioned to use R1/R2 as 10x the values — this would be great to cut down parasitic drain, which is a problem I’m trying to address. How would this work exactly in the voltage divider, and the values to use in the firmware? Anyone try this or should it work ok?

Depends a lot on the type of circuit breaker or fuse. Some large 15A breakers will easily supply 20-25A forever. The slimmer type, especially if next to another loaded circuit, may not fare as well. I used to have a microwave pulling 19A (official rating was 1500W…) on a 15A circuit together with about 2-3A of lighting. The lights would dim when using the microwave… but the breaker never tripped. The only sure way to find out is to try it.

Pro Tip: You want those breakers to trip. It’s what they were designed for. If they aren’t tripping on overcurrent, they’re not doing their job and are very dangerous! :open_mouth: Worse, the issue might not be the breaker itself, but the wiring. It could be already damaging your electronics. Sorry to be so alarmist, but as an electrician, I’m trained to care about these things.

I decided to give the large heat gun that’s been lying around my job (for a few decades) a try. I think it’s great for emitters but it doesn’t give me much/enough control on driver boards. I wanted to touch up some resistors on the edge of the board but I couldn’t avoid desoldering the MPU and 7135 at the same time. The FET wasn’t affected — it was far enough away. If I can’t fashion a nozzle for it I’ll gladly likely spring for the 858D. Now that I think about it, the air flow with a nozzle on that gun would be far too high… Parts would be flying everywhere. A purpose built hot air station would be worth a few bucks.

FWIW, after watching the technique shown at the 1:40 mark in this video I’ve been pretty happy with most surface mount work using an iron. However the pads on some of our drivers are so small it’s a bit more difficult.

No worries, said microwave is now on its own 20A circuit. I was just pointing out that 15A is not a hard limit. Few breakers will trip right at 15A and properly installed wiring won’t magically burn up at 16A. But you certainly already know that :slight_smile: In fact, the only wiring I’ve hard melt down on me was crappy aluminium (probably on the wrong type of socket) in an apartment building from the 70s. It was only lightly loaded.

Hello everyone .
After making some wight’s 17mm fet drivers (A17DD) , i think i should step to this driver now .
So , first question : Which package of attiny is compatible with these drivers (if i want to use attiny 25/85) . SSU ? or what ?

Also , which version of the board i should use and which is the preffered components list ?

thanksss

The parts list is the same as the A17DD, with the addition of a 7135 chip.

If you are using in an e-switch light, you may want to substitute the resistors with 10x higher values, as has been recently discussed, to lower the parasitic drain when not in use.

I’m using v009, not sure on the differences of the later revisions.

Thank you FmC !
Any clue about which version of the board i should use ? I’m not interested in e-switch.
Also which package of attiny i should use . On A17DD i used attiny13a-SSU . So in attiny 25/85 still SSU is what i need ?

Attiny25v-SSU would be the right size. the 85 doesn’t come in SSU package so you would have to use the SU package and bend the legs under, but it’s workable.

I’m not current on the different board versions though