Title: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 04, 2012, 08:47:15 pm
Post by: HammerFET on February 04, 2012, 08:47:15 pm
Hi all, I've already spoken to some of you on the blog about this idea but I'll repost everything here to make sure we're all on the same page.
So far I've gotten hold of an RT8 tip for the Weller WSM1 and similar controllers. I'm trying to build my own small form factor controller for these tips. A simple controller that can fit inside the barrel of the soldering pen handle is my aim and using a couple of buttons and some LEDs to show temperature in increments of 25degC. I plan to use a micro controller in order to control the thing and run it off a small laptop supply.
First of all I need to figure out how this tip works. There is a headphone style connector on it that I've read the following resistances:
The three conductors I'll refer to as TIP, MIDDLE and SLEEVE.
TIP conductor is not to be mistaken for the physical soldering tip of the iron, I can't help but use them interchangeably...
The SLEEVE conductor is a hard connection to the entire barrel of the soldering tip. The black rubber grip is also conductive.
So far I've determined this:
I have no idea what's between the MIDDLE and SLEEVE, I initially thought it was a thermocouple but I don't read anything useful off it.
In fact I read strange voltages and resistances out of it when I connect the supply to the heater. ranging from a few mV to a couple volts.
This leads me to believe there is some connection between the TIP and MIDDLE??
I used a DC bench supply to power the heater incrementing up in 1V steps and logging the temperature. I can get the soldering tip up to 300deC (as measured by holding a temp meter against the end of it) with 4V 2A (8W) input. I tried soldering with this set at 8W and saw no fluctuation in voltage or current as the iron cooled then heated again.
I put 4W into the MIDDLE conductor again referenced to the SLEEVE conductor and got nothing useful at the soldering tip in terms of heat. If anything, the barrel heated up...
So I cracked open the soldering tip and found this...
The SLEEVE is connected to that thin tube that I chopped off from the soldering tip to get the barrel off. Inside the thin tube were two wires:
Each is insulated in heat proof material however the conductors inside seem to be of different material. My meter didn't note anything very different about them in terms of resistance/length but then again, I have a cheap meter that barley measures down to 0.1ohm.
This tip is meant to be 12V and 40W rated but I haven't dared put 12V across it as it would exceed 40W unless I limited the current. I'm also guessing that the tip should only receive 40W for a short amount of time to crank it up to working temperature, I can solder fine with it running off 8W of power however takes about 30seconds to heat up.
This tip is also designed to be ESD safe where the SLEEVE conductor would be referenced to ground via a large resistor? If the heater is actually between the TIP and MIDDLE, surely there would be a voltage on the SLEEVE.
I've had another person who has these tip and the WSM1 station confirm they have the same resistances between conductors and their tip is working fine.
Any ideas on what kind of pinout this thing has?
So far I've gotten hold of an RT8 tip for the Weller WSM1 and similar controllers. I'm trying to build my own small form factor controller for these tips. A simple controller that can fit inside the barrel of the soldering pen handle is my aim and using a couple of buttons and some LEDs to show temperature in increments of 25degC. I plan to use a micro controller in order to control the thing and run it off a small laptop supply.
First of all I need to figure out how this tip works. There is a headphone style connector on it that I've read the following resistances:
The three conductors I'll refer to as TIP, MIDDLE and SLEEVE.
TIP conductor is not to be mistaken for the physical soldering tip of the iron, I can't help but use them interchangeably...
The SLEEVE conductor is a hard connection to the entire barrel of the soldering tip. The black rubber grip is also conductive.
So far I've determined this:
I have no idea what's between the MIDDLE and SLEEVE, I initially thought it was a thermocouple but I don't read anything useful off it.
In fact I read strange voltages and resistances out of it when I connect the supply to the heater. ranging from a few mV to a couple volts.
This leads me to believe there is some connection between the TIP and MIDDLE??
I used a DC bench supply to power the heater incrementing up in 1V steps and logging the temperature. I can get the soldering tip up to 300deC (as measured by holding a temp meter against the end of it) with 4V 2A (8W) input. I tried soldering with this set at 8W and saw no fluctuation in voltage or current as the iron cooled then heated again.
I put 4W into the MIDDLE conductor again referenced to the SLEEVE conductor and got nothing useful at the soldering tip in terms of heat. If anything, the barrel heated up...
So I cracked open the soldering tip and found this...
The SLEEVE is connected to that thin tube that I chopped off from the soldering tip to get the barrel off. Inside the thin tube were two wires:
Each is insulated in heat proof material however the conductors inside seem to be of different material. My meter didn't note anything very different about them in terms of resistance/length but then again, I have a cheap meter that barley measures down to 0.1ohm.
This tip is meant to be 12V and 40W rated but I haven't dared put 12V across it as it would exceed 40W unless I limited the current. I'm also guessing that the tip should only receive 40W for a short amount of time to crank it up to working temperature, I can solder fine with it running off 8W of power however takes about 30seconds to heat up.
This tip is also designed to be ESD safe where the SLEEVE conductor would be referenced to ground via a large resistor? If the heater is actually between the TIP and MIDDLE, surely there would be a voltage on the SLEEVE.
I've had another person who has these tip and the WSM1 station confirm they have the same resistances between conductors and their tip is working fine.
Any ideas on what kind of pinout this thing has?
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 04, 2012, 08:48:13 pm
Post by: HammerFET on February 04, 2012, 08:48:13 pm
Sorry about the links, this is my first post so I'm not aloud to have any URLs ¬_¬
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arakis on February 04, 2012, 09:18:30 pm
Post by: arakis on February 04, 2012, 09:18:30 pm
I'll edit your post and add the urls
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arakis on February 04, 2012, 09:23:42 pm
Post by: arakis on February 04, 2012, 09:23:42 pm
Welcome to the forum.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: ginpb on February 04, 2012, 10:36:59 pm
Post by: ginpb on February 04, 2012, 10:36:59 pm
Hi, you can measure the temperature in two ways (using just wire) with a thermocouple or thermistor. With the first one you would get a voltage read, really low voltage. With the second one you will get a variation on the resistence. Probably you already know all this.
I don't believe that is a thermistor, you should notice a variation on the resistance, it's pretty hard not notice a variation on the resistance for that kind of temperature range.
Most probably it's a thermocouple, because they are cheap and work really great at high temperatures. There is another option that is using a semiconductor (like a diode) but from what i see this is not the case. So most probably you are dealing with a thermocouple, i cannot say which type. Probably your DMM cannot measure the low voltage generated from the thermocouple.
I don't believe that is a thermistor, you should notice a variation on the resistance, it's pretty hard not notice a variation on the resistance for that kind of temperature range.
Most probably it's a thermocouple, because they are cheap and work really great at high temperatures. There is another option that is using a semiconductor (like a diode) but from what i see this is not the case. So most probably you are dealing with a thermocouple, i cannot say which type. Probably your DMM cannot measure the low voltage generated from the thermocouple.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 04, 2012, 11:05:24 pm
Post by: HammerFET on February 04, 2012, 11:05:24 pm
Hi and thanks for the warm welcome!
My meter has a temperature measurement function for use with k-type thermocouples, this is what I've been using so far both for using the probe to measure tip temperature and also taking the reading from the connector itself.
It's odd that I read voltage between the MIDDLE and SLEEVE connectors when it's powered, in the order of mV and V, this isn't thermocouple range. That's what is making my meter read in the order of 1000s of degC.
My meter has a temperature measurement function for use with k-type thermocouples, this is what I've been using so far both for using the probe to measure tip temperature and also taking the reading from the connector itself.
It's odd that I read voltage between the MIDDLE and SLEEVE connectors when it's powered, in the order of mV and V, this isn't thermocouple range. That's what is making my meter read in the order of 1000s of degC.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: ginpb on February 04, 2012, 11:25:12 pm
Post by: ginpb on February 04, 2012, 11:25:12 pm
there's a lot of thermocouples out there, maybe a really rare type is used. More important, the value do you read is temperature dependent?
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 05, 2012, 12:24:36 am
Post by: HammerFET on February 05, 2012, 12:24:36 am
That's the thing, it jumps around as I vary the input voltage, not if I change the temp of the iron by dunking it in water while it's hot to make it cold.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arhi on February 05, 2012, 01:19:36 am
Post by: arhi on February 05, 2012, 01:19:36 am
[quote author="HammerFET"]
TIP conductor is not to be mistaken for the physical soldering tip of the iron, I can't help but use them interchangeably...
[/quote]
A hint that might help make things clearer and easier to read
TIP == soldering iron tip (ESD)
center pin == "tip of the banana connector"
TIP conductor is not to be mistaken for the physical soldering tip of the iron, I can't help but use them interchangeably...
[/quote]
A hint that might help make things clearer and easier to read
TIP == soldering iron tip (ESD)
center pin == "tip of the banana connector"
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arhi on February 05, 2012, 02:06:30 am
Post by: arhi on February 05, 2012, 02:06:30 am
[quote author="HammerFET"]That's the thing, it jumps around as I vary the input voltage, not if I change the temp of the iron by dunking it in water while it's hot to make it cold.[/quote]
If it was thermocouple you;d read the temperature easily. 99% chance is that it is a PTC style thermistor. Measure resistance, heat the tip up, measure resitance again. Note that PTC's and NTC's as very non linear and the ones chosen for soldering irons are linear (almost) in the 220-450C range so measuring the resistance change in the below 200C range will not help a lot. Most of them also have saddle curve so in low temperature range (below 100C) the resistance first fall's and then rises so the same resistance can represent 2 different temperatures... of course when they go over 200C they behave good so the only way to test the sensor is to heat the tip up to 200+C
If it was thermocouple you;d read the temperature easily. 99% chance is that it is a PTC style thermistor. Measure resistance, heat the tip up, measure resitance again. Note that PTC's and NTC's as very non linear and the ones chosen for soldering irons are linear (almost) in the 220-450C range so measuring the resistance change in the below 200C range will not help a lot. Most of them also have saddle curve so in low temperature range (below 100C) the resistance first fall's and then rises so the same resistance can represent 2 different temperatures... of course when they go over 200C they behave good so the only way to test the sensor is to heat the tip up to 200+C
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 05, 2012, 02:15:54 am
Post by: HammerFET on February 05, 2012, 02:15:54 am
I had a feeling it could be a thermistor, it would explain why I get several kohm readings from it once it heats up, I think by having put 2V @ 2A into it, I may have toasted it. I'll try get hold of another another tip soon and start fresh.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arhi on February 05, 2012, 02:31:18 am
Post by: arhi on February 05, 2012, 02:31:18 am
you should read it by pushing 1mA constant current trough it. Check out the SID schematic, you will find the PTC sensor read circuit there that works :)
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 22, 2012, 06:33:12 pm
Post by: HammerFET on February 22, 2012, 06:33:12 pm
Ok guys, got a new tip and I think I've cracked it. The idea seems to be that the temperature is read while the heater is inactive. Also I believe it could contain some kind of thermocouple because the tip seems to show a similar behaviour to all my other thermocouples. The MIDDLE to SLEEVE has a 1.1ohm resistance that quickly becomes zero and stays at zero once the tip heats up to soldering temperature (therefore can't be a PTC). I read 3.15mA between these points once the temperature reached the point to just melt some lead free silver solder. Then measure 0.07mV at room temperature. Remember these are values I see once power is disconnected, else I read 0V
I have also noticed the change in resistance as tip temperature rises. My previous experiment didn't give me this so I'm putting it down to having burnt something out. I get between TIP and MIDDLE 3.1ohm at room temp and 35ohms at soldering temperature. Again I have to remove power to get this reading, else it reads a short. It's also a pretty smooth curve all the way up.
So, I'm wondering how to go about making this controller. Do I make use of what seems to be a thermocouple, or just read the resistance between TIP and MIDDLE.
Note that this is not the heater resistance (TIP to SLEEVE), but rather something between the TIP and MIDDLE (looking at the above diagram from my first post, I haven't put anything there...). Could be a PTC, but can you get PTCs that are this low resistance? I thought they read in the kohm range
I have also noticed the change in resistance as tip temperature rises. My previous experiment didn't give me this so I'm putting it down to having burnt something out. I get between TIP and MIDDLE 3.1ohm at room temp and 35ohms at soldering temperature. Again I have to remove power to get this reading, else it reads a short. It's also a pretty smooth curve all the way up.
So, I'm wondering how to go about making this controller. Do I make use of what seems to be a thermocouple, or just read the resistance between TIP and MIDDLE.
Note that this is not the heater resistance (TIP to SLEEVE), but rather something between the TIP and MIDDLE (looking at the above diagram from my first post, I haven't put anything there...). Could be a PTC, but can you get PTCs that are this low resistance? I thought they read in the kohm range
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on February 24, 2012, 03:10:20 pm
Post by: HammerFET on February 24, 2012, 03:10:20 pm
Right I've got it working! So forgetting what I wrote in the last post, it was late and the stuff I wrote about resistance was rubbish. Starting fresh... :P
I'm reading the thermocouple output (between SLEEVE and MIDDLE) using an AD8495 thermocouple amplifier. This reading is going into an AVR and I'm get a nice analogue value to work the control with. The amplifier goes to the high rail whenever the heater is active, then gives out a mV reading once the heater is turned off. Hence to keep from hurting the AVR, I run the amplifier off the 3.3V rail.
I'm now building a driver circuit with a couple MOSFETs and will feed some bursts of PWM into it. During the time between the bursts I can read the amplifier output voltage.
Hopefully that will allow me to create the control system to run the tip at a stable temperature. I believe a PID controller is what I should use. However I still have another year at university before they teach us that >.< anyone know any good sites I can learn about them from?
In other parts of the design I've got myself an ADXL335 3 Axis Accelerometer. This should give a good indication of then the iron is being used from movement. I'm trying to keep the devices analogue so I can use the internal clock of the AVR. I believe that I2C parts can't be used with an external oscillator or crystal. Am I right?
I plan to use two small tactile switches and eight 0604 blue LEDs to indicate temperature. The entire thing will be housed in a 10mm OD/8mm ID aluminium tube. The 3.5mm jack will solder directly to the board so the entire controller with switches and LEDs will be housed inside the barrel of the pen. I plan to use a 12V 50W laptop supply I have to power it.
Pictures of breadboard and schematics soon...
I'm reading the thermocouple output (between SLEEVE and MIDDLE) using an AD8495 thermocouple amplifier. This reading is going into an AVR and I'm get a nice analogue value to work the control with. The amplifier goes to the high rail whenever the heater is active, then gives out a mV reading once the heater is turned off. Hence to keep from hurting the AVR, I run the amplifier off the 3.3V rail.
I'm now building a driver circuit with a couple MOSFETs and will feed some bursts of PWM into it. During the time between the bursts I can read the amplifier output voltage.
Hopefully that will allow me to create the control system to run the tip at a stable temperature. I believe a PID controller is what I should use. However I still have another year at university before they teach us that >.< anyone know any good sites I can learn about them from?
In other parts of the design I've got myself an ADXL335 3 Axis Accelerometer. This should give a good indication of then the iron is being used from movement. I'm trying to keep the devices analogue so I can use the internal clock of the AVR. I believe that I2C parts can't be used with an external oscillator or crystal. Am I right?
I plan to use two small tactile switches and eight 0604 blue LEDs to indicate temperature. The entire thing will be housed in a 10mm OD/8mm ID aluminium tube. The 3.5mm jack will solder directly to the board so the entire controller with switches and LEDs will be housed inside the barrel of the pen. I plan to use a 12V 50W laptop supply I have to power it.
Pictures of breadboard and schematics soon...
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: sdixon on February 24, 2012, 07:20:13 pm
Post by: sdixon on February 24, 2012, 07:20:13 pm
I haven't actually used it yet but this project (http://http://www.ospid.com/blog) seems to have a nice explanation of PID controllers and a good Arduino library. Notably, it includes autotuning for the PID parameters.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: sdixon on February 24, 2012, 07:23:49 pm
Post by: sdixon on February 24, 2012, 07:23:49 pm
Further on the osPID library, this (http://http://brettbeauregard.com/blog/2011/04/improving-the-beginners-pid-introduction/) series of blog posts gives a good overview of how you code a PID library up.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: HammerFET on May 22, 2012, 09:53:50 am
Post by: HammerFET on May 22, 2012, 09:53:50 am
It's been a while but I've managed to run a couple boards with the design. They are eagle format so feel free to take a look. based around an ATMEGA168, there is a thermocouple amp, accelerometer, and a couple buttons and LEDs. Quite a small system so it can fit into the barrel of the pen. The MOSFET should be okay running 24V with a good few amps but I haven't tested it yet. I've got it all running except the micro. Can't seem to get it programmed using an arduino set up as a programmer. As a side note, the three pole connector at one end of the board is for a headphone jack, specifically this one LUMBERG - KLB 4: http://uk.farnell.com/lumberg/klb-4/soc ... dp/1200144 (http://uk.farnell.com/lumberg/klb-4/socket-3-5mm-jack-chassis/dp/1200144) It's mounted by just sliding the terminals between the PCB and they line up perfect, just needs to be the right way around.
I haven't worked on it in a wile due to exams and such but might get back to it at some point. I've recently bought a "hakko-like" soldering station and hot air gun so got less motivation to finish this. If anyone is interested in finishing it, feel free, just remember that the amplifier only gives good readings where there is no power to the tip, i.e. between pwm bursts.
http://www.2shared.com/file/iMGlir1r/So ... onics.html (http://www.2shared.com/file/iMGlir1r/Soldering_Pencil_Electronics.html)
I haven't worked on it in a wile due to exams and such but might get back to it at some point. I've recently bought a "hakko-like" soldering station and hot air gun so got less motivation to finish this. If anyone is interested in finishing it, feel free, just remember that the amplifier only gives good readings where there is no power to the tip, i.e. between pwm bursts.
http://www.2shared.com/file/iMGlir1r/So ... onics.html (http://www.2shared.com/file/iMGlir1r/Soldering_Pencil_Electronics.html)
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: basreflex on February 02, 2013, 12:32:09 pm
Post by: basreflex on February 02, 2013, 12:32:09 pm
I took some signals off the handle when driven with the WD2M station.
I get tip errors when a large H field is present.
no idea where to post the tiff files...
I get tip errors when a large H field is present.
no idea where to post the tiff files...
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: arhi on February 02, 2013, 02:28:42 pm
Post by: arhi on February 02, 2013, 02:28:42 pm
you can convert tiff files to jpg and upload here, or you can zip them and upload zip here
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: sparkybg on February 28, 2013, 12:51:55 pm
Post by: sparkybg on February 28, 2013, 12:51:55 pm
So, it is a series thermocouple? If so, it is just like the HAKKO T12/T15 tips. ;)
...but, there's a HAKKO T12 clone tips you can get for $4 per piece.
...but, there's a HAKKO T12 clone tips you can get for $4 per piece.
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: Mockus on June 24, 2013, 03:09:48 pm
Post by: Mockus on June 24, 2013, 03:09:48 pm
Hello everybody!
Im a first year applied physics student and also work a part time job as an electronics engineer's assistant. At work I had the pleasure of using a JBC CD-B soldering station and instantly fell in love with it, but since their prices are so enormously high its going to be a while since I can afford one for myself. So I decided to try and build one from available parts. About a month ago I came across an RT8 tip from Weller which was quite nicely built and had all the properties I was looking for, so I decided to apply some physics and made some measurement using the equipment at work during lunch. This is what I came up with:
The tip was being heated with a hot air station in approximately 10K intervals with a K-type thermocouple pressed against the surface of the tip measuring the actuall surface temperature, allowing the measurements to stabilize before writing them down.
Voltage generated by the thermocouple inside the RT8 tip was read using a multimeter set on microvolts range.
Temperature measured with: PeakTech 2010 DMM
Voltage measured with: Agilent U1270
Ambient temperature at the start of measurements: 300K
Attached are two pictures showing the polynomial curves of various types of thermocouples and the data that i collected. In the first picture You can see how the dots follow the curve of the type-D thermocouple although the emf seems to be low. Now I went off the scientific road a bit and made an assumption that it is indeed a type-D and compensated for the cold junction (+0,273mV) and innitial microvolt meter offset (+0,045mV). I think that the deviations are within the margin of error and the RT8 tip indeed has a type-D thermocouple built into it.
I would like to ask the good members of this forum to take a look at my measurements and maybe dismiss or confirm what I have found?
Thanks!
Im a first year applied physics student and also work a part time job as an electronics engineer's assistant. At work I had the pleasure of using a JBC CD-B soldering station and instantly fell in love with it, but since their prices are so enormously high its going to be a while since I can afford one for myself. So I decided to try and build one from available parts. About a month ago I came across an RT8 tip from Weller which was quite nicely built and had all the properties I was looking for, so I decided to apply some physics and made some measurement using the equipment at work during lunch. This is what I came up with:
The tip was being heated with a hot air station in approximately 10K intervals with a K-type thermocouple pressed against the surface of the tip measuring the actuall surface temperature, allowing the measurements to stabilize before writing them down.
Voltage generated by the thermocouple inside the RT8 tip was read using a multimeter set on microvolts range.
Temperature measured with: PeakTech 2010 DMM
Voltage measured with: Agilent U1270
Ambient temperature at the start of measurements: 300K
Attached are two pictures showing the polynomial curves of various types of thermocouples and the data that i collected. In the first picture You can see how the dots follow the curve of the type-D thermocouple although the emf seems to be low. Now I went off the scientific road a bit and made an assumption that it is indeed a type-D and compensated for the cold junction (+0,273mV) and innitial microvolt meter offset (+0,045mV). I think that the deviations are within the margin of error and the RT8 tip indeed has a type-D thermocouple built into it.
I would like to ask the good members of this forum to take a look at my measurements and maybe dismiss or confirm what I have found?
Thanks!
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: neslekkim on June 24, 2013, 09:35:55 pm
Post by: neslekkim on June 24, 2013, 09:35:55 pm
you should checkout this thread also:
viewtopic.php?f=56&t=5264 (http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=5264)
viewtopic.php?f=56&t=5264 (http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=5264)
Title: Re: Custom Weller WSM 1 style controller for RT series tips
Post by: Mockus on June 26, 2013, 12:05:31 pm
Post by: Mockus on June 26, 2013, 12:05:31 pm
Yeah, I took a look at that thread, but Im probably going to stick too my own design. I plan to use an ATmega to control the voltage to the heater by PWM, and drive a small 64x128 LCD which is going to be used for various user settings like working temp, idle temp, etc. Im also going to amplify and convert the thermocouple reading (also measure the ambient temperature) right inside the handle of the soldering iron for the best possible accuracy. The data will be fed to the ATmega via TWI and all of the calculations will be based on the polynomial curves i've posted before.