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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
Posted to rec.crafts.metalworking
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Ping: Iggy
Hey Iggy,
I am in the process of converting my buzzbox to something resembling a 150A TIG supply. I already have the AC-DC section figured out, as well as the HF area. I believe you used SCRs in a circuit you used to control the output current of one of your machines, and I am very interested in this. Do you by any chance have a schematic of this section of your circuit, and/or any other reference schematics of going about this topology for a high current supply? Thanks for your help, Jon |
#2
Posted to rec.crafts.metalworking
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Ping: Iggy
On 2008-04-28, Jon Danniken wrote:
Hey Iggy, I am in the process of converting my buzzbox to something resembling a 150A TIG supply. I already have the AC-DC section figured out, as well as the HF area. What is your OCV? I believe you used SCRs in a circuit you used to control the output current of one of your machines, and I am very interested in this. Do you by any chance have a schematic of this section of your circuit, and/or any other reference schematics of going about this topology for a high current supply? Jon, I have some documentation along with parts pictures, sample welds, etc, he http://igor.chudov.com/projects/Weld...New-Rectifier/ If your welder is single phase (mine is 3 phase), it changes a lot due to ripple. All together, this was a moderately expensive project and I would be better off just buying a nice welder. It was fun, but very time consuming. I also post the source code of my welder, written in BASIC, he http://igor.chudov.com/projects/Weld...ier/source.txt It is under GPL, so feel free to do whatever you want with it, as long as you keep it free software. i |
#3
Posted to rec.crafts.metalworking
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Ping: Iggy
"Ignoramus18948" wrote:
, Jon Danniken wrote: Hey Iggy, I am in the process of converting my buzzbox to something resembling a 150A TIG supply. I already have the AC-DC section figured out, as well as the HF area. What is your OCV? 80V on the low range, for AC. I'll probably lose a bit after it goes through the bridge. I believe you used SCRs in a circuit you used to control the output current of one of your machines, and I am very interested in this. Do you by any chance have a schematic of this section of your circuit, and/or any other reference schematics of going about this topology for a high current supply? Jon, I have some documentation along with parts pictures, sample welds, etc, he http://igor.chudov.com/projects/Weld...New-Rectifier/ If your welder is single phase (mine is 3 phase), it changes a lot due to ripple. All together, this was a moderately expensive project and I would be better off just buying a nice welder. It was fun, but very time consuming. I also post the source code of my welder, written in BASIC, he http://igor.chudov.com/projects/Weld...ier/source.txt It is under GPL, so feel free to do whatever you want with it, as long as you keep it free software. Sure, thanks Iggy. I forgot yours was a three phase sysem, which does shift things around a bit. I'll look through the page you provided, that looks like a good place to start. Thanks, Jon |
#4
Posted to rec.crafts.metalworking
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Ping: Iggy
On 2008-04-28, Jon Danniken wrote:
"Ignoramus18948" wrote: , Jon Danniken wrote: Hey Iggy, I am in the process of converting my buzzbox to something resembling a 150A TIG supply. I already have the AC-DC section figured out, as well as the HF area. What is your OCV? 80V on the low range, for AC. I'll probably lose a bit after it goes through the bridge. I believe you used SCRs in a circuit you used to control the output current of one of your machines, and I am very interested in this. Do you by any chance have a schematic of this section of your circuit, and/or any other reference schematics of going about this topology for a high current supply? Jon, I have some documentation along with parts pictures, sample welds, etc, he http://igor.chudov.com/projects/Weld...New-Rectifier/ If your welder is single phase (mine is 3 phase), it changes a lot due to ripple. All together, this was a moderately expensive project and I would be better off just buying a nice welder. It was fun, but very time consuming. I also post the source code of my welder, written in BASIC, he http://igor.chudov.com/projects/Weld...ier/source.txt It is under GPL, so feel free to do whatever you want with it, as long as you keep it free software. Sure, thanks Iggy. I forgot yours was a three phase sysem, which does shift things around a bit. I'll look through the page you provided, that looks like a good place to start. Another point is, SCR driver boards are expensive. I was very lucky in that for some readon, PCTI liked my kids site algebra.com so much that they donated a SCR driver device to me, which was easy to use. Still, I would be far better off applying my efforts elsewhere, wotking less hours, and buying a great new welder. That said, I learned something. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#5
Posted to rec.crafts.metalworking
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Ping: Iggy
"Ignoramus18948" wrote:
Another point is, SCR driver boards are expensive. I was very lucky in that for some readon, PCTI liked my kids site algebra.com so much that they donated a SCR driver device to me, which was easy to use. Still, I would be far better off applying my efforts elsewhere, wotking less hours, and buying a great new welder. That said, I learned something. Those are some good points you make there. I guess what I am trying to do is use a handfull of discrete componenets to make as simple of a variable-current supply as I can get away with. Perhaps the only way to control the current is with a highly-advanced topology, utilizing complex circuit boards, but if there is a way to do it with a minimum of components, then I am going to try to do this. I guess what I really need is to look at a schematic of a transformer-based TIG supply that used SCRs to control the output current, and see how they did it there, but I don't know the name of any units that used such a control method, much less have a schematic. Jon |
#6
Posted to rec.crafts.metalworking
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Ping: Iggy
On 2008-04-29, Jon Danniken wrote:
"Ignoramus18948" wrote: Another point is, SCR driver boards are expensive. I was very lucky in that for some readon, PCTI liked my kids site algebra.com so much that they donated a SCR driver device to me, which was easy to use. Still, I would be far better off applying my efforts elsewhere, wotking less hours, and buying a great new welder. That said, I learned something. Those are some good points you make there. I guess what I am trying to do is use a handfull of discrete componenets to make as simple of a variable-current supply as I can get away with. Perhaps the only way to control the current is with a highly-advanced topology, utilizing complex circuit boards, but if there is a way to do it with a minimum of components, then I am going to try to do this. I guess what I really need is to look at a schematic of a transformer-based TIG supply that used SCRs to control the output current, and see how they did it there, but I don't know the name of any units that used such a control method, much less have a schematic. Look at the manual of Miller Syncrowave 250. I believe that it includes an intelligible schematic and uses SCRs. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#7
Posted to rec.crafts.metalworking
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Ping: Iggy
"Ignoramus18948" wrote:
Jon Danniken wrote: Those are some good points you make there. I guess what I am trying to do is use a handfull of discrete componenets to make as simple of a variable-current supply as I can get away with. Perhaps the only way to control the current is with a highly-advanced topology, utilizing complex circuit boards, but if there is a way to do it with a minimum of components, then I am going to try to do this. I guess what I really need is to look at a schematic of a transformer-based TIG supply that used SCRs to control the output current, and see how they did it there, but I don't know the name of any units that used such a control method, much less have a schematic. Look at the manual of Miller Syncrowave 250. I believe that it includes an intelligible schematic and uses SCRs. Aye, thanks Iggy, that is a readable schem. It looks like they are using the SCRs in place of the bridge for controlling the current, but are using an IC (or another unspecified group of components) to drive the gates. I wonder if there were any TIG supplies that used a more simple method of controlling the current, maybe in the pre-IC days? Jon |
#8
Posted to rec.crafts.metalworking
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Ping: Iggy
On 2008-04-29, Jon Danniken wrote:
"Ignoramus18948" wrote: Jon Danniken wrote: Those are some good points you make there. I guess what I am trying to do is use a handfull of discrete componenets to make as simple of a variable-current supply as I can get away with. Perhaps the only way to control the current is with a highly-advanced topology, utilizing complex circuit boards, but if there is a way to do it with a minimum of components, then I am going to try to do this. I guess what I really need is to look at a schematic of a transformer-based TIG supply that used SCRs to control the output current, and see how they did it there, but I don't know the name of any units that used such a control method, much less have a schematic. Look at the manual of Miller Syncrowave 250. I believe that it includes an intelligible schematic and uses SCRs. Aye, thanks Iggy, that is a readable schem. It looks like they are using the SCRs in place of the bridge for controlling the current, but are using an IC (or another unspecified group of components) to drive the gates. Yes, that's why you need an SCR controller to go with the SCRs. I wonder if there were any TIG supplies that used a more simple method of controlling the current, maybe in the pre-IC days? Don mentioned another method. I do not recall what it is. This is a project that I am kind of happy that it worked, but I regret starting it, the time wasted, etc. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#9
Posted to rec.crafts.metalworking
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Ping: Iggy
"Ignoramus29893" wrote:
Jon Danniken wrote: Aye, thanks Iggy, that is a readable schem. It looks like they are using the SCRs in place of the bridge for controlling the current, but are using an IC (or another unspecified group of components) to drive the gates. Yes, that's why you need an SCR controller to go with the SCRs. Thanks Iggy. I am going to build this myself (with some assistance from those more experienced, of course), using available discreet components (maybe an IC if there is a compelling reason), without purchasing any pre-assembled circuitry or boards. This will entail building my own "controller board" to control the SCRs, but that's part of the fun, too! Before I can do that, however, I need to first determine the topology that is used in this type of circuit (silicon control of current in a welder). I am hoping I can come across an early TIG supply schematic that will give me clue as to what methodology was used, be it pre-transformer control or post-transformer control. That's where I'm stuck at right now. I wonder if there were any TIG supplies that used a more simple method of controlling the current, maybe in the pre-IC days? Don mentioned another method. I do not recall what it is. IIRC, he mentioned he would use IGBTs, but I think that might be more complicated than I am williing to go, at least at this stage. SCRs don't seem too terribly complicated for me, it's just finding out the layout of a basic welder current control to give me a place to start that is my obstacle right now. Eventually there will be zero-crossing detectors, but one step at a time. Jon |
#10
Posted to rec.crafts.metalworking
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Ping: Iggy
On 2008-04-29, Jon Danniken wrote:
"Ignoramus29893" wrote: Jon Danniken wrote: Aye, thanks Iggy, that is a readable schem. It looks like they are using the SCRs in place of the bridge for controlling the current, but are using an IC (or another unspecified group of components) to drive the gates. Yes, that's why you need an SCR controller to go with the SCRs. Thanks Iggy. I am going to build this myself (with some assistance from those more experienced, of course), using available discreet components (maybe an IC if there is a compelling reason), without purchasing any pre-assembled circuitry or boards. This will entail building my own "controller board" to control the SCRs, but that's part of the fun, too! Before I can do that, however, I need to first determine the topology that is used in this type of circuit (silicon control of current in a welder). I am hoping I can come across an early TIG supply schematic that will give me clue as to what methodology was used, be it pre-transformer control or post-transformer control. That's where I'm stuck at right now. The topology is that of a regular rectifier bridge (1 or 3 phase), but with SCR instead of diodes. The SCR drivers need to do a lot of things. I wonder if there were any TIG supplies that used a more simple method of controlling the current, maybe in the pre-IC days? Don mentioned another method. I do not recall what it is. IIRC, he mentioned he would use IGBTs, but I think that might be more complicated than I am williing to go, at least at this stage. SCRs don't seem too terribly complicated for me, it's just finding out the layout of a basic welder current control to give me a place to start that is my obstacle right now. Eventually there will be zero-crossing detectors, but one step at a time. I have a big SCR assembly for sale. $100 plus shipping for Rec.Crafts.Metalworking. http://yabe.algebra.com/~ichudov/mis...ristor-Bridge/ The price is not negotiable, as the scrap value of copper in there exceeds the above amount. i -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#11
Posted to rec.crafts.metalworking
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Ping: Iggy
"Ignoramus29893" wrote:
Jon Danniken wrote: Before I can do that, however, I need to first determine the topology that is used in this type of circuit (silicon control of current in a welder). I am hoping I can come across an early TIG supply schematic that will give me clue as to what methodology was used, be it pre-transformer control or post-transformer control. That's where I'm stuck at right now. The topology is that of a regular rectifier bridge (1 or 3 phase), but with SCR instead of diodes. Thanks, Iggy. Digging around more it does seem to be common on some TIG machines; I will go with this. The SCR drivers need to do a lot of things. I wonder if there were any TIG supplies that used a more simple method of controlling the current, maybe in the pre-IC days? Don mentioned another method. I do not recall what it is. IIRC, he mentioned he would use IGBTs, but I think that might be more complicated than I am williing to go, at least at this stage. SCRs don't seem too terribly complicated for me, it's just finding out the layout of a basic welder current control to give me a place to start that is my obstacle right now. Eventually there will be zero-crossing detectors, but one step at a time. I have a big SCR assembly for sale. $100 plus shipping for Rec.Crafts.Metalworking. http://yabe.algebra.com/~ichudov/mis...ristor-Bridge/ You have mail. Jon |
#12
Posted to rec.crafts.metalworking
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Ping: Iggy
Jon,
I too am trying to do this except I already have a AC/DC Tig welder with high frequency. Its an Lincoln Idealarc 300 and does not have true squarewave. All I want to try is to generate a squarewave output w/ variable frequency (20 - 300 Hz) So what I am going to do (or at least try) is to take the DC side of it and run it through an H bridge using 4 IGBT's. I will drive them similar to the circuit at this site: http://www3.telus.net/public/a5a26316/TIG_Welder.html It might be along the lines of what you are trying to doing. I give credit to Iggy, he too has invested a lot of time into this. |
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