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Treadmill motor controller question. (Don Foreman, Wayne Cook?)
Back in 1998 several folks bought a 2 hp treadmill motor and control.
I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, Eric R Snow |
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About 5 years ago I bought 2 of these motors and put one on my 12" Enco
lathe, keeping the other as a spare. It was a little underpowered for the size of the lathe but I'm still using it. I went through several controllers before I found out how flimsy they are. The main thing I learned was DO NOT reverse the motor while it is turning, center-off switch or not. Recently I decided to use my other motor on my drill press. I had several controllers lying around but they were defunct so I thought of using a Minarik type control. I posted a message to this group asking if this would work satisfactorily, since this is a series-wound motor. Luckily a gentleman on this NG was kind enough to send me a controller and I'm now in the process of connecting it up. It took me a little while to remember how I got it to reverse, since It's a series wound motor, reversing the polarity won't do it. What you have to do is run the current from the controller through the field and then into your DPDT switch so the relationship of the current flow between the field and armature can be reversed. If this is not any clearer than mud I can draw you a schematic. I've found out this motor can be overloaded heavily and it just slows down after a certain point after trying to maintain constant speed and does not blow fuses or smoke out. Engineman1 Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, |
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On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow)
wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Don can answer this question better than I can. The truth is that I was just the one who reverse engineered the schematic. Everybody else came up with the mods and I just repeated them. All I can say is that I had mine wired on my old Shop Task so that I could reverse it. I can't remember exactly how I wired it but I do know that you've got to reverse the connection of the brush wires to do it. I used the original switch that came with the lathe for reversing the induction motor. In truth they both reverse about the same way with the reversing of two wires. Thus I believe it was wired so that the power to the controller was turned off before turning it to the other direction. I think this is a pretty good idea considering how overloaded the triac is on these to begin with. As for problems with the controllers experience by me and others has shown that the most common problem was bad solder joints on the triac. It had to carry a lot of power and the solder joints where not up to the job. I believe the motors are capable of a fair bit of power. However the controllers are to light and the current limit they're designed for doesn't allow you to get the full power out of the motor. I found that it was about equal to using 1/2 to 3/4 HP motor. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm |
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On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow)
wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, Eric R Snow I don't think I posted a circuit mod. I'm just back from a fun fishin' ' trip in the northwoods and am half full of beer so I'd best say no more beyond noting some interest in chasing this further (later) if anybody cares. Having fun is job 1, tellyawhut, that was one fun fishin' trip! YUM Autumn is already upon the Nortthland, crisp mornings with warm days. It's risky driving at night because there are so many deer. Didn't see any bears, though plenty of scat. I've not hunted since military days but I still enjoy being afield. |
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On Wed, 31 Aug 2005 23:17:12 -0500, Wayne Cook
wrote: On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow) wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Don can answer this question better than I can. The truth is that I was just the one who reverse engineered the schematic. Everybody else came up with the mods and I just repeated them. All I can say is that I had mine wired on my old Shop Task so that I could reverse it. I can't remember exactly how I wired it but I do know that you've got to reverse the connection of the brush wires to do it. I used the original switch that came with the lathe for reversing the induction motor. In truth they both reverse about the same way with the reversing of two wires. Thus I believe it was wired so that the power to the controller was turned off before turning it to the other direction. I think this is a pretty good idea considering how overloaded the triac is on these to begin with. As for problems with the controllers experience by me and others has shown that the most common problem was bad solder joints on the triac. It had to carry a lot of power and the solder joints where not up to the job. I believe the motors are capable of a fair bit of power. However the controllers are to light and the current limit they're designed for doesn't allow you to get the full power out of the motor. I found that it was about equal to using 1/2 to 3/4 HP motor. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm Thanks Wayne. Eric |
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On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow)
wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, Eric R Snow In order to reverse it you must reverse the connection of the field relative to the armature. Just reversing the connections to the motor won't do it. The armature gets its juice thru the brushes, so that's a good place to do your reversing: just reverse the brush connections with a DPDT switch. "Instant reverse" by throwing this switch with power on would work, but I wouldn't recommend it. It would result in a current spike that would very likely blow something. Better to turn off and stop before reversing. There was some stuff in the original controller schematic that must have been particular to a treadmill. A basic controller could be somewhat simpler. You can download a datasheet for the TDA1085 chip from http://www.datasheetcatalog.com/data.../TDA1085.shtml This has a schematic for a controller using this chip. The tacho is non-directional, doesn't matter which way the motor is turning. I would use robust triacs, 25 or 35 amp 600 volt devices, well heatsunk. |
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On Thu, 01 Sep 2005 12:46:36 -0500, Don Foreman
wrote: On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow) wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, Eric R Snow In order to reverse it you must reverse the connection of the field relative to the armature. Just reversing the connections to the motor won't do it. The armature gets its juice thru the brushes, so that's a good place to do your reversing: just reverse the brush connections with a DPDT switch. "Instant reverse" by throwing this switch with power on would work, but I wouldn't recommend it. It would result in a current spike that would very likely blow something. Better to turn off and stop before reversing. There was some stuff in the original controller schematic that must have been particular to a treadmill. A basic controller could be somewhat simpler. You can download a datasheet for the TDA1085 chip from http://www.datasheetcatalog.com/data.../TDA1085.shtml This has a schematic for a controller using this chip. The tacho is non-directional, doesn't matter which way the motor is turning. I would use robust triacs, 25 or 35 amp 600 volt devices, well heatsunk. Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. If a more robust triac was used would the rest of the components be still be at risk when instant reversing? If so, would using DPDT center off switch to reverse the field winding connections be OK to use if the center off position was held until the motor has stopped before changing rotation? Thanks, Eric |
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On Thu, 01 Sep 2005 12:48:25 -0700, Eric R Snow
wrote: Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. If a more robust triac was used would the rest of the components be still be at risk when instant reversing? If so, would using DPDT center off switch to reverse the field winding connections be OK to use if the center off position was held until the motor has stopped before changing rotation? Thanks, Eric The only problem I see is that you'll need to do some work on getting the current sensing right. In the original controller the PCB trace acts as the current sensing resister. If you go with a bigger triac you'll have to move all the current carrying components away from the board since it's not built well enough to handle higher currents. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm |
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On Thu, 01 Sep 2005 12:48:25 -0700, Eric R Snow
wrote: On Thu, 01 Sep 2005 12:46:36 -0500, Don Foreman wrote: On Thu, 01 Sep 2005 00:43:09 GMT, tesnow@whidbeyDOTcom (Eric R Snow) wrote: Back in 1998 several folks bought a 2 hp treadmill motor and control. I was one of them. A circuit mod was posted by, I think, Don Foreman. I believe it was Wayne Cook who figured out how to mod the circuit. Finally I'm going to actually use this motor to power a small lathe. I would like to have instant reverse and stop. Turning the power to the board on and off will work for starting the motor. A DPDT switch could be used between the control and the motor to reverse the connection and hence the rotation. But this scheme won't work for instant reverse. If the DPDT switch is used without first turning off the AC will this damage the control? If a center off switch is used could this be used instead of switching on and off the ACto the control? Since the control uses a tach for speed feedback will the control be damaged by trying to spin the motor to the speed set by the pot? I looked on the web and found both the motor control chip and the triac. If these did fry they can be replaced for about 10 bucks including shipping. But I'd rather not try anything without some guidance. Thanks, Eric R Snow In order to reverse it you must reverse the connection of the field relative to the armature. Just reversing the connections to the motor won't do it. The armature gets its juice thru the brushes, so that's a good place to do your reversing: just reverse the brush connections with a DPDT switch. "Instant reverse" by throwing this switch with power on would work, but I wouldn't recommend it. It would result in a current spike that would very likely blow something. Better to turn off and stop before reversing. There was some stuff in the original controller schematic that must have been particular to a treadmill. A basic controller could be somewhat simpler. You can download a datasheet for the TDA1085 chip from http://www.datasheetcatalog.com/data.../TDA1085.shtml This has a schematic for a controller using this chip. The tacho is non-directional, doesn't matter which way the motor is turning. I would use robust triacs, 25 or 35 amp 600 volt devices, well heatsunk. Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. If a more robust triac was used would the rest of the components be still be at risk when instant reversing? I don't think so, other than perhaps the current sense resistor. However, if the triac does get zorched it may take the chip with it. The TDA1085 has a "ramping" function to ramp speed up at a controlled rate. That would be inoperative if you hot-reversed. However, it also has a current limit function that serves to limit peak triac current. If so, would using DPDT center off switch to reverse the field winding connections be OK to use if the center off position was held until the motor has stopped before changing rotation? Thanks, Eric I think so. That's what I'd do. I'd probably add a 200-volt MOV across the triac to soak up any voltage spikes. I think I'd use an alternistor rather than a triac, or perhaps an SCR inside a 35-amp fullwave bridge. Alternistor: Teccor, Q4040K7 or Q6040K7, available from Digi-Key. These are 40-amp parts, 400 and 600 volt respectively, $6.35 and $7.02 respectively. These devices are more tolerant of inductive loads than triacs, behave more like back-to-back SCR's. Nice thing about "rolling yer own" is that you don't have to shave the last nickel out of the design so you can design conservatively for performance and robustness. These alternistors are rated for a 1-cycle surge of 400 amps. My experience with triacs is that they are most reliable when conservatively rated (voltage and current) and well heatsunk. Designs that operate triacs near their spec limits have high failure rates in the field. |
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On Thu, 01 Sep 2005 12:48:25 -0700, Eric R Snow
Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. I never did figure out that schematic. It may be a brilliant design, but it sure baffled me. ( Failure reports suggest that perhaps it is less than brilliant.) I'd go with the one on the datasheet, realizing that you may need to do some tweaking to make it operate satisfactorily. It is a closed-loop control system with significant gain, so it may need a little tuning with a specific motor size and type. |
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On Thu, 01 Sep 2005 18:06:32 -0500, Wayne Cook
wrote: On Thu, 01 Sep 2005 12:48:25 -0700, Eric R Snow wrote: Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. If a more robust triac was used would the rest of the components be still be at risk when instant reversing? If so, would using DPDT center off switch to reverse the field winding connections be OK to use if the center off position was held until the motor has stopped before changing rotation? Thanks, Eric The only problem I see is that you'll need to do some work on getting the current sensing right. In the original controller the PCB trace acts as the current sensing resister. If you go with a bigger triac you'll have to move all the current carrying components away from the board since it's not built well enough to handle higher currents. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm If you use the original controller board, meant to operate the treadmill motor, using a bigger triac won't change the current. Current is determined by the controller and the motor. A bigger triac will switch about like a smaller one. It's just less likely to fail under the same conditions. Better heatsinking of the triac would also be a good idea. |
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On Thu, 01 Sep 2005 20:10:11 -0500, Don Foreman
wrote: On Thu, 01 Sep 2005 18:06:32 -0500, Wayne Cook wrote: On Thu, 01 Sep 2005 12:48:25 -0700, Eric R Snow wrote: Greetings Don, I looked up the devices a couple days ago and read the data sheets. I also have the schematic that was posted in 1998. I don't really understand the schematic very well but was able to determine that the TDA1085 controlled the triac. If a more robust triac was used would the rest of the components be still be at risk when instant reversing? If so, would using DPDT center off switch to reverse the field winding connections be OK to use if the center off position was held until the motor has stopped before changing rotation? Thanks, Eric The only problem I see is that you'll need to do some work on getting the current sensing right. In the original controller the PCB trace acts as the current sensing resister. If you go with a bigger triac you'll have to move all the current carrying components away from the board since it's not built well enough to handle higher currents. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm If you use the original controller board, meant to operate the treadmill motor, using a bigger triac won't change the current. Current is determined by the controller and the motor. A bigger triac will switch about like a smaller one. It's just less likely to fail under the same conditions. Better heatsinking of the triac would also be a good idea. True but I was thinking in the case of increasing the current some. These controllers peak at 9 amps. I can't remember off hand but I believe the motor is rated for a lot more than that. My only problem with these on my Shop Task was that it simply didn't have the power I wanted. I was always running into that current limit. Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm |
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