I blame you all, and specially Dave! - Page 1
Forum section: electronics / projects

author: Mikey
author_rank: Regular Contributor
timestamp: September 15, 2012, 04:38:18 pm
content: Let's see if some of you feel guilty!After browsing this forum, and watching a lot of the video's on youtube, I got hooked on trying to design my own boards, and also using SMT. So today I just did my first attempt at reflow soldering, and here is the result:It is not complicated, not perfect, but it is my first! What makes this cool too, is that I had no oven to do it, no fancy hot air rework station, all I had was a bunch of these pcb's, the parts needed, some soldering paste, and my stove... So the paste was applied, the components placed, and the board put on one of the hotplates on the stove, and it worked!!!And for this, I blame a lot of you! Thank you!

author: muvideo
author_rank: Frequent Contributor
timestamp: September 15, 2012, 04:53:19 pm
content: Well done.The first time you see the components reflow and thesolder become shiny and with the right curvature, it seemlike magicI've used (and still use sometime...) a cheap electric grillfor quick prototypes, it is aluminium and has the warmup and cool down times that seem right for the job, itworks very well, and I had no problems also on delicatecomponents. Cast Iron tend to be less controllable.Mine seem like this one:If you still havent, it's time to search for a cheap stencil cut service.Naturally when money and reliability is involved it's a different story.Fabio.

author: Mikey
author_rank: Regular Contributor
timestamp: September 15, 2012, 05:01:58 pm
content: To start with, I think I need quantity more than quality, so I got stuff to practice on.I am working on another hotplate too, originally it was a melt pot of some kind, someone send to me by a mistake, and I got nothing to do with such a pot, so I am converting it into a small hotplate instead.

author: johnnyfp
author_rank: Frequent Contributor
timestamp: September 15, 2012, 09:39:55 pm
content: I've got a cheap electric frying pan from my local cheapo store which works ok, but I found that the surface has several hot spots where the element is passing through the pan.I've seen some people do quite well with ovens, but the professionals use infrared ovens. Wonder if you can buy cheapo IR ovens from the local elcheapo store.

author: notsob
author_rank: Frequent Contributor
timestamp: September 15, 2012, 10:03:06 pm
content: I saw a yutube of a dudes cnc machine (redfrog I think) he placed a sheet of aluminium foil down first to distribute the heat ( cheap aluminium skiddle type heater) seemed to work ok

author: Mikey
author_rank: Regular Contributor
timestamp: September 16, 2012, 09:32:07 am
content: Did a bit of testing of that sensor, and it seems to be plenty accurate for what I need it for.The next problem is that it does not work as expected...I have to remove the ACT led, and both 4.7nF capacitors, otherwise the output just stays high, no matter if the magnet is present or not. It should go low when the magnet is present.

author: Mikey
author_rank: Regular Contributor
timestamp: September 16, 2012, 12:28:38 pm
content: Maybe one of you evil geniuses can see if I did something wrong here?Datasheet for the sensor:https://dl.dropbox.com/u/10098610/datasheets/TLE4905.pdf(this is not the same as the first one in this thread, the difference is the dimension of the board, and the led was moved from GND to 5V so it will light up when the magnet is present, instead of the opposite)

author: muvideo
author_rank: Frequent Contributor
timestamp: September 16, 2012, 01:34:09 pm
content: That 33 ohm resistors seem too low, probably you intended 330ohm.With red leds the current will be around 90mA and about 40 for blue ones.Fabio.

author: Mikey
author_rank: Regular Contributor
timestamp: September 16, 2012, 01:47:40 pm
content: Quote from: muvideo on September 16, 2012, 01:34:09 pmActually, the led is QUITE bright too... That might explain why... But can that have something to do with it not going high and low properly?

author: muvideo
author_rank: Frequent Contributor
timestamp: September 16, 2012, 02:04:18 pm
content: Dont know, just try with much higher resistors, around 1K, and check,probably the leds will light up and be visible with 1 or 2mA.Also try without ferrous materials around, put it near and far from themagnet with bare hands so you are sure there are no magnetized objectsaround like screws or metallic plates.I imagine that the magnet will approach the sensor from the side, thesensor will "cut trough the magnetic field"... dont know how to sayin english without a drawing

author: ptricks
author_rank: Frequent Contributor
timestamp: September 16, 2012, 03:35:43 pm
content: If you really want to get into doing reflow at home check out some of the toaster oven conversions . They are not that complicated to do.Basically just a controller to turn on and off the oven at various times through the process.magazine article with detailshttp://www.nutsvolts.com/uploads/magazine_downloads/932/OvenFlow.pdf

author: Mikey
author_rank: Regular Contributor
timestamp: September 16, 2012, 04:03:22 pm
content: Quote from: ptricks on September 16, 2012, 03:35:43 pmI am going to make a dedicated oven for it, if it catch on... So far I am just using what I got laying around already, or what I can make for free at work.But my biggest problem right now, is that this sensor does not behave as it should, and I am not sure why.

author: mtkaalund
author_rank: Contributor
timestamp: September 16, 2012, 06:14:52 pm
content: Now I can see that you are from Denmark, an oven you could use for making it into a reflow oven could behttp://www.harald-nyborg.dk/p6101/wasco-miniovn-18l

author: Mikey
author_rank: Regular Contributor
timestamp: September 16, 2012, 07:04:19 pm
content: Quote from: mtkaalund on September 16, 2012, 06:14:52 pmSeems to be in budget for a thing that is never meant to be used as for what it was designed for.- Update -Been looking at multiple diy's, and there is one thing I miss... What would be best to do? Top heat, bottom heat? Or just give it the lot?And I see many just use a timer, x seconds on, x seconds off, x seconds on, then off again and the cycle is done... Would using PID and using a microcontroller be better perhaps? Could be handy to be able to set a temperature, and then be able to get to it pretty precise without overshooting. (It is already being used in the firmware I got in my 3d printer, and it is hitting the temperature within 1c)- Update again -Do you have any experience with this oven? Would it be able to match, or come close to a profile like this?Or does it even matter? (I will most likely mostly be soldering resistors, led's, capacitors, mosfets, and stuff like that)

author: onlooker
author_rank: Frequent Contributor
timestamp: September 17, 2012, 01:13:16 am
content: QuoteAs already mentioned, 33 R may make TLE 4905 L working at about the max 100mA limit.The other possibility is that the magnet is placed in a wrong orientation. The datasheet was showing the South on the "Branded Side" (whatever this means?). Do you have this arrangment in your setup?

author: Mikey
author_rank: Regular Contributor
timestamp: September 17, 2012, 10:32:29 am
content: Quote from: onlooker on September 17, 2012, 01:13:16 amI tried without the resistor and ACT led in too, still same thing. I have made some more modifications. According to the specs of the led's I am going to put on, the resistors should have them to operate at 20mA.

author: Mikey
author_rank: Regular Contributor
timestamp: September 22, 2012, 10:01:25 am
content: Started to brainstorm a bit about this project...Will continue the reflow oven project here:https://www.eevblog.com/forum/projects-designs-and-technical-stuff/diy-reflow-oven/