HM for a B+(work in progress)


 
J

John Bostwick

TVWBB Wizard
The last 3 or 4 days I have been painstakingly making a smd version of the Heatermeter and in the process have made what I think also will fit a B+. Not all the components are smd and some would not make that much difference, like the barrel caps, although you could get them in an smd version, they are expensive and not worth it.

So, I replaced all the resisters, shift resister, BS170's and 1700, diodes, 16mhz resonator, .1 caps to smd versions. I moved the RpI header 7.62mm to the left, so that the lcd does not hit the Cat5 jack on the B+. The LCD and Button have not moved. the LEDs are just below the LCD on the right. Also, I have to move the cat5 jack and AC jack to the bottom. This is actually, I think, a good place as, not as good if everything was one side though, but better then having wires on both sides.

The biggest thing is that the board atm would be about $8 cheaper for 3 of them at $34.95, and the parts, which I have not figured out yet, would be about the same cost.

I have not tested and its still in the works and very much a work in progress and its not an official HM from Bryan. But here is a pic of my sloppy eagle work, lol.

2n88msw.png
 
I made a mock up of what the board set should look like (rPi B+) for this board:
HMB+.jpg


It looks like you've got some space under the last USB header, you could extend the HM board and get at least the CAT5 jack in there on the side? The grey box represents approx height that you would need to fit the CAT5 jack and the power jack on that side, perhaps the HM board could be taller and not as wide? Or maybe use a different power jack that doesn't have the leg kicked out to the side like this one? That would allow to go snug up against the CAT5 jack and take less space on the board.
 
Yeah, it could be reworked to be a bigger board, but was trying to get it smaller. what's the point to have the Cat5 and AC jack on the side if it will make the board much bigger and a lot more. Just did an estimate on OSH and to have the Jacks on the side would make the cost almost $47 for 3.
 
$15 each, $12 each... in the big picture not all that much difference, and the overall board size and cost could be reduced by using the extra area shown in grey and making the board not so wide... but I hang my HM on a magnet or lay it flat on its back usually so having cables on the bottom is not a big deal to me.
 
Need a socket for that one, guess it would be better to use a SMD socket rather than smd chip, so you solder the socket rather than the chip.
 
I just discovered a co-worker at work who has a CNC machine, 3d printer, laser etcher, pick and place machine, solder paste mask machine, reflow oven, and all kinds of other electronic toys in his home basement. My jaw hit the floor (especially when he told me he does it all for hobby and nothing really for commercial purposes). The pick and place machine he's been building up is a Madell DP2006-2. He creates surface mount projects that looks like complete professional jobs in production. I should ask him who he uses for his circuit boards again because it seemed REALLY cheap when he originally told me how much he was getting for boards. I think he was cutting his own out of panels though (using his CNC machine).

His basement pick and place machine could probably kick out these HM boards with SMT/SMD parts in less than 5 minutes. My jaw hit the floor.

Check out some of these videos:
https://www.youtube.com/watch?v=lSC2UD1l4zw
https://www.youtube.com/watch?v=GIr-aq3ZxkA
https://www.youtube.com/watch?v=7UL5_8M-AC4
https://www.youtube.com/watch?v=H08SmZGS_Is
 
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My company that I work for, makes carrier tapes for various pick and place machines.

When I first started making HMs, before we had OSH, I played around etching boards and button boards. Boards themselves are cheap and you can make a CNC machine to make pretty good boards. But, all the steps needed and all the time stuff needed, OSH is so much better.
 
I used to work for a circuit board shop many years ago. I don't recommend etching your own boards either. I wasn't saying my friend at work did his own etching. He basically sent out the job for full panels and got the panel back. Then he CNC'd the parts (boards for various projects) out of that panel. I'm not sure what OSH charges per panel but I was getting the impression he got his prices really low and the quality looked great from what I could see. OSH quality looks great too so I'm not complaining. Just saying that if you're going surface mount direction you could probably really get this HM much smaller and then use some of these machines to build them as a complete unit.

I built my HM for about $235. I bet this could get down to $150 or less with surface mount and professional packaging. This makes it compete very well with some of the other commercial stuff I see out there in this area.

I love my HM now. Now I just wish it was waterproof or resistant.
 
Yup nice! As you see the HeaterMeter is not a complicated design and you can really throw something together pretty quickly especially in SMD. The size is pretty much dictated by where you want the connectors and how many you want. I don't want any connectors along the bottom so the device can stand up on the bottom edge. There's also a number of design improvements in 5.0 to further reduce analog noise and replace the EOL'ed button, but yeah it is bigger just because of these requirements.
 
Standing the HM on it's edge doesn't seem worthy of working the design around IMHO, after you have all the cables connected to the HM it seems likely the HM will fall over pretty easily while standing on edge? I've always laid my HM on its back, unless mounting it with a magnet, never really stood it on end...

Quick survey, how many people stand their HM (sitting on the bottom edge) when they use it??
 
RalphTrimble said:
Standing the HM on it's edge doesn't seem worthy of working the design around IMHO, after you have all the cables connected to the HM it seems likely the HM will fall over pretty easily while standing on edge? I've always laid my HM on its back, unless mounting it with a magnet, never really stood it on end...

Quick survey, how many people stand their HM (sitting on the bottom edge) when they use it??
Click to expand...

Not me. It's not exactly stable when standing up on the bottom edge. I'd be fine with plugging things into the bottom.
 
That's kinda what I thought, unless the case was MUCH thicker the HM isn't gonna be very stable when standing on end, so keeping the bottom end free of connections is not a huge factor IMHO.
 
I would prefer a smaller case with bottom connectors over a large case with connectors on the side. Just my €0.02 !
 
It's only 3.6"x3.6"x1.6" so I'm not sure footprint-size it makes much difference. Just eyeballing it looks like something like 3"x4" for this? And the through-hole for easy assembly would have to be bigger. (Also support for 4 buttons)
 
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