Author Topic: JBC-mini - a low cost T245 handle controller  (Read 45476 times)

0 Members and 1 Guest are viewing this topic.

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #25 on: June 15, 2014, 08:32:08 pm »
I will look into that. In principle this should not pose much problem. It will require additional set of MOSFETs and optocouplers. Opamp that I chose is already a dual channel one, so no problem there.

I think my project is quite economical:

T245 handpiece - 63€ (TME)
some tip, eg C245939 - 35€ (TME)
24V, 150VA toroidal transformer - 19€ (toroidy.pl - local Polish manufacturer), almost any other transformer can be used (i use 12V/300VA in the prototype and it works just fine)
STM32F051K6 - 2.5€ (Farnell)
RPC1-6RB-12P connector - 2.8€ (Farnell)
PCB - ~2€/piece from Elecrow if it fits on 10x10cm format
MCP6V02 opamp - 2.2€
Enclosure - http://www.kradex.com.pl/shop?product=287 Local Polish manufacturer, they have english version of the website but i dunno if they ship abroad. If anything, I can buy and distribute that to people. Anyway - appropriate enclosure is under 2€.

Other bits and pieces like displays, encoder, optocouplers, trimpots and the like can be had from anywhere or from junk, so I won;t bother listing them, as anybody probably has them in their junkpile. So the control units sums up to 30€ for major components. Even assuming that the rest will cost another 30€, this is still cheap :)
I love the smell of FR4 in the morning!
 

Online tautech

  • Super Contributor
  • ***
  • Posts: 29810
  • Country: nz
  • Taupaki Technologies Ltd. Siglent Distributor NZ.
    • Taupaki Technologies Ltd.
Re: JBC-mini - a low cost T245 handle controller
« Reply #26 on: June 15, 2014, 08:57:39 pm »
I love a good rats nest.  >:D
Keen to see your finished PCB.
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
 

Offline dannyf

  • Super Contributor
  • ***
  • Posts: 8221
  • Country: 00
Re: JBC-mini - a low cost T245 handle controller
« Reply #27 on: June 15, 2014, 09:04:48 pm »
Quote
So the control units sums up to 30€

I think I can get mine under $10:

mcu: <$2.
led display: <$1.
mosfet: <$1.
encoder: $1.
misc. parts: $1.
laptop power supply: free.
================================
https://dannyelectronics.wordpress.com/
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #28 on: June 15, 2014, 10:02:03 pm »
I don't doubt that, but JBC T245-A handpiece and C245 cartridges are superior to hakko, especially when it comes to power and ability to handle large thermal masses which is important to me as I do quite a lot of power electronics.

« Last Edit: June 15, 2014, 10:05:17 pm by poorchava »
I love the smell of FR4 in the morning!
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #29 on: July 20, 2014, 12:36:09 pm »
Some update :).
I have selected an enclosure and made a PCB for it.




I'm hoping to order the PCB some time soon.
I love the smell of FR4 in the morning!
 

Offline bdivi

  • Regular Contributor
  • *
  • Posts: 108
  • Country: bg
Re: JBC-mini - a low cost T245 handle controller
« Reply #30 on: February 03, 2015, 11:00:22 pm »
Long time no news  :) any update with this project ?
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #31 on: February 04, 2015, 12:30:05 pm »
It's on hold right now.

I've assembled most of the circuit (excluding the thermocouple interface section) and the project has been put on hold due to shitload of commercial work. What's done so far:

-power supply is working as it should
-uC works and communicates with debugger
-led display works and displays garbage as expected (segment connections have been changed since the prototype but code was not updated)
-AC switch works after some modification that involved getting rid of PNP transistors that were driving mosfets. Right now mosfets are driven by optocouplers directly. The optocouplers I chose have proven to have too high dark current and small signal PNPs with high hfe would turn on spontaneously
-zero detection works after a little 'woops' which involved a double diode in a diode bridge being put onto schematic in reverse direction, and this resulted in sudden disappearance of the diode together with a few milimeters of pcb track. Anyway - it works now.

I'm gonna work on it further, but right now I'm sleeping 2-3 hours a day and have no time to work on private projects.
I love the smell of FR4 in the morning!
 

Offline dom0

  • Super Contributor
  • ***
  • Posts: 1483
  • Country: 00
Re: JBC-mini - a low cost T245 handle controller
« Reply #32 on: March 03, 2015, 07:43:31 pm »
Do you know what kind of connector they use and if it's available commercially?
Could you confirm if the cold junction is indeed in the hand piece (or in the connector)?

I'm currently thinking about something similar, since I have most of (the cheap) parts for something similar at hand (power supply, some chopper op amps, and the usual other stuff). But I'd use one of the laptop supplies from my stock (have plenty of 60 and 90 W bricks) for the power part. Heating with DC shouldn't be an issue and saves one switching element plus the opto-couplers and zero-crossing detection stuff.
« Last Edit: March 03, 2015, 07:45:49 pm by dom0 »
,
 

Online ajb

  • Super Contributor
  • ***
  • Posts: 2786
  • Country: us
Re: JBC-mini - a low cost T245 handle controller
« Reply #33 on: March 03, 2015, 08:24:12 pm »
The connectors are Hirose RPC1.  They're available for a few bucks in single quantities from Mouser.

I've had a T245 handle and panel mount connector sitting around for several months for a similar project, just haven't gotten around to doing much of anything with it.

Regarding using a DC supply, I've read in other discussions some warnings that using DC can shorten the life of the heater due to electromigration, but I haven't really seen any specifics as to how substantial the loss of lifespan is, or if electromigration is even a concern with the types of heating elements JBC uses.  The JBC cartridges are expensive enough that saving two or three cartridge replacements over the lifetime of the base station probably justifies the extra cost of using an AC supply.  On the other hand, the cartridge replacements would be a deferred expense...
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #34 on: March 03, 2015, 08:51:20 pm »
Yep the connectors are available.

As for the cold junction compensation,  I'm almost sure that there is none in the handpiece,  unless they somehow use the handpiece-cartridge connection as a thermocouple (I don't know how feasible is that and what is the contact material). Since they sense the handpiece being put in the stand,  they might be compensating somehow based on how long the handpiece has been held in hand, but this would only be a very minor adjustment.

DC heater drive would be fine if synchronous rectification was used,  such as the Linear replace-diode-bridge-with-mosfets chip. Otherwise rectifiers would dissipate a good few watts of power.  Schottky rectifiers are no good, as they usually have  relatively high reverse leakage current,  which would distort thermocouple readings. The heater switch needs to be really high impedance in the off-stage. The AC switch which I have developed is cheap,  simple and the power dissipation is negligible. The only important point is that the optocoupler collector-emitter voltage has to be higher that peak AC voltage.

I really regret not being able to work on this project right now, as I could REALLY use a new iron.
I love the smell of FR4 in the morning!
 

Offline dom0

  • Super Contributor
  • ***
  • Posts: 1483
  • Country: 00
Re: JBC-mini - a low cost T245 handle controller
« Reply #35 on: March 03, 2015, 09:27:11 pm »
With a floating heater supply a standard N-Ch MOSFET should do the trick, given that the heater supply (and thus Vgs) is only floated by thermovoltage
« Last Edit: March 03, 2015, 09:28:47 pm by dom0 »
,
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #36 on: March 03, 2015, 09:39:32 pm »
The switching element has to have a high off-state impedance, because the switched end of the heater is the thermocouple connection at the same time, so a slightest current flow will throw off the measurement, as the thermocouple is not particularily sensitive (like 2.8-3mV @ dT=300 deg.C) the amplifier has really high gain (in the order of several hundred). The floating gate drive storage capacitor is fed through the parasitic body diodes of the mosfets, so the temperature measurement must occur near zero-crossing, because at that moment the charge pump does not draw current through body diodes, and also interferences are at their lowest.
I love the smell of FR4 in the morning!
 

Offline fredboivin

  • Regular Contributor
  • *
  • Posts: 52
  • Country: ca
Re: JBC-mini - a low cost T245 handle controller
« Reply #37 on: June 04, 2015, 07:41:03 pm »
Hi, very interesting project!

Do you know how JBC does its sleep and tip changing poweroff? In the UniSolder, Sparkybg does it with an IR sensor, but I'd like to know how has JBC implemented it.

Thanks!
 

Offline savril

  • Regular Contributor
  • *
  • Posts: 66
  • Country: fr
Re: JBC-mini - a low cost T245 handle controller
« Reply #38 on: June 05, 2015, 12:52:45 am »
Hi, very interesting project!

Do you know how JBC does its sleep and tip changing poweroff? In the UniSolder, Sparkybg does it with an IR sensor, but I'd like to know how has JBC implemented it.

Thanks!

Watch Dave tear-down video on the JBC. The iron holder has a wire that get it linked with the base station. When the iron is in the holder, the iron touch a metallic surface. So it is as simple as detecting that the metal in the holder is connected to ground. When you see that other shops are using accelerometers for that  :-DD.

For the tip, it detect that there is no resistance (by current measurement ?). In Sparkybg design, he use the resistance to differentiate the different irons and it also detect the tip changing (but for JBC it's not named tip but cartridge because it contain the heating element).
 

Offline fredboivin

  • Regular Contributor
  • *
  • Posts: 52
  • Country: ca
Re: JBC-mini - a low cost T245 handle controller
« Reply #39 on: June 05, 2015, 02:01:49 am »
Ahhhh, I must have missed it! I should have known a reputable company like JBC would keep it stupid simple.

But, isn't the cartridge at 180degC? How do they keep that wire from heating up?

Thank you very much!
« Last Edit: June 05, 2015, 02:58:22 am by fredboivin »
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #40 on: June 06, 2015, 12:47:36 pm »
I have no idea to be honest. My best guess is that connections between the cartridge and the handpiece have low ohmic resistance,  but rather small cross section and therefore thermal coupling is not very good.

On the other hand JBC really knows metallurgy. On one occasion by a mistake in the software I got the tip to white-hot-and-glowing state,  and after it has cooled down it still worked ok...

Wys?ane z mojego GT-I9100 przy u?yciu Tapatalka

I love the smell of FR4 in the morning!
 

Offline fredboivin

  • Regular Contributor
  • *
  • Posts: 52
  • Country: ca
Re: JBC-mini - a low cost T245 handle controller
« Reply #41 on: June 06, 2015, 01:42:12 pm »
I looked a little more at the handpiece anatomy and noticed that it's the metal ring at the end of the piece (which is not supposed to get hot) that acts as a contact for the sleep mode. The cartridge changing tool is wired to another pin, but doesn't get hot because the tip isn't heated anymore.
 

Offline Didgitalpunk

  • Contributor
  • Posts: 24
  • Country: fr
Re: JBC-mini - a low cost T245 handle controller
« Reply #42 on: July 26, 2015, 04:53:28 pm »
Very cool project! can't wait to see it finished.
Btw, when you have time, would you mind sharing the PCB layout files and parts list? schematics? I'm quite interested to do one myself and I think quite a couple folks here are as well :)

« Last Edit: July 26, 2015, 11:05:33 pm by Didgitalpunk »
 

Offline timofonic

  • Frequent Contributor
  • **
  • Posts: 904
  • Country: es
  • Eternal Wannabe Geek
Re: JBC-mini - a low cost T245 handle controller
« Reply #43 on: August 20, 2015, 02:21:51 am »
Any news about it? JBC are nice, buy their stations are very expensive.

They are from my country, Spain. I'm happy there's something good here...
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #44 on: September 25, 2015, 08:25:59 am »
Heh,  still no time to finish the project. I'm working on it hour or two a week, but unfortunately I can't devote more time to it.

But no fear,  the project is definitely not dead.


Sent from my HTC One M8s using Tapatalk

I love the smell of FR4 in the morning!
 

Offline cam

  • Newbie
  • Posts: 5
  • Country: fr
Re: JBC-mini - a low cost T245 handle controller
« Reply #45 on: November 25, 2015, 07:12:11 pm »
Hi,

I actually own a JBC BT-2BWA which is the analog version of the CD-B. I am more into the analog one because I believe it is easier to set the temperature with it but unfortunately it doesn't has the temperature reading.

I googled around for infos about where to read this temperature so I could build a display (most likely with 7 digits displays) and guess what... I found your topic which looks the most detailed about the T245 pencil. First I'd like to thank you for sharing what you're building, it is well regarded as JBCs costs a lot but are THE soldering stations!
Now, I was wondering how you read the temperature from the connector? I didn't get much time to go through the design of a soldering station since I own a good one  ;D

Your input would be much appreciated  :-+ Thanks!
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #46 on: November 25, 2015, 07:48:29 pm »
There is an mcp9700 temperature sensor on the PCB near the openocd for the connector. The sensor is THT so it may be mounted on the connector itself if need be (not sure what would the fastening metod be though).

Sent from my HTC One M8s using Tapatalk.

I love the smell of FR4 in the morning!
 

Offline cam

  • Newbie
  • Posts: 5
  • Country: fr
Re: JBC-mini - a low cost T245 handle controller
« Reply #47 on: November 25, 2015, 08:02:27 pm »
Thanks for the fast answer.

I'm not sure how it is supposed to work, MCP9700 seems to work from -40C to +150C.
How is it suppose to measure up to the 450°C the soldering station can do?
 

Offline poorchavaTopic starter

  • Super Contributor
  • ***
  • Posts: 1673
  • Country: pl
  • Troll Cave Electronics!
Re: JBC-mini - a low cost T245 handle controller
« Reply #48 on: November 25, 2015, 08:33:21 pm »
Umm,  the MCP9700 is for cold junction compensation. The connector which is in the handpiece is not accounted for. I think that if we assume that all the contacts are at the same temperature and the emf generated across them is similar,  then they will compensate one another. Also,  the thermal isolation between heater and the contacts is excellent. I could have the tip at 350 deg.C and I could hold the other end of the cartridge with my bare hand it was only a bit warm.

Also, I don't think It very important for a soldering iron to be accurate to half a degree or something. I assumed that +/-5 degrees is perfectly fine.

Sent from my HTC One M8s using Tapatalk.

I love the smell of FR4 in the morning!
 

Offline cam

  • Newbie
  • Posts: 5
  • Country: fr
Re: JBC-mini - a low cost T245 handle controller
« Reply #49 on: November 26, 2015, 06:18:42 am »
Thanks again for the fast answer  :-+

Sorry I don't know much about this component I did not know about which made ask stupid question.
I looked at the datasheet and basically I just need to find a suitable uC with a ADC input to feed the 7 segments. it's just a matter of converting the Vout pin of the MCP9700 to binary. There is no compensation to take care of if I use the Vout pin of the MCP9700 because it is what is used for the regulation in JBC electronic card. Did I get it right?

Thanks again, your topic convinced me I can, without too much trouble, add a digital display on my station.
I'll post update later when I have time to work on it.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf