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Author Topic: Can two 36v power supplies be used in series to get 72v?  (Read 31559 times)

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #50 on: April 25, 2009, 09:37:10 PM »
It does appear to have dual outputs, so it may be worth investigating the AC secondary voltage values, it would not be hard to modify.
 

We have a guy who is obviousl not terribly adept with electrinics.  Do you *really* want to have him modifying a fairly high-power piece of electronics by remote control?  Sounds like a recipe for disaster (and possibly a trip to the emergency room) to me....

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #51 on: April 26, 2009, 02:54:43 AM »
Thanks to everyone for the education. Here is what I learned primarily:

It is a lot more complicated that I imagined. There is no agreement at all on how to go about this.

I'm an engineer who spent many years building prototypes of all kinds and doing fault analysis on machines and packaging lines and I had a machine shop with my own heat treating furnace. I cut all kinds of exotic high strength materials including H7 H11, Inconel, Ampco Bronze, etc. I'm a newbee at building my own CNC, but I'm not inexperienced at machining or mechanical design.

While I am definately not up to speed on electronics, I've done work at a Chlorine plant where the cell rows run at hundreds of KV. When you walk the 'tunnel' which has fiberglass grating, your skin tingles and your hair stands up. Needless to say, I know enough to not blow myself up. I think "don't touch the wires that are making that crackly sound" is a good rule . .LOL!


Anyway, this issue is now moot as my solution was to buy a NEMA 34 72V servo motor from www.homeshopcnc.com   

I also have on order replacment power transistors that *might* fix my existing 36V supply (yes, I'm handy with a soldering iron, as well as a desoldering iron). If so, then maybe I'll get another Gecko and use the little 36V servo on my troublesome Y axis, otherwise, I'll just pitch the PS and sell off the little servo and move forward. 

« Last Edit: April 26, 2009, 02:57:50 AM by simpson36 »
Re: Can two 36v power supplies be used in series to get 72v?
« Reply #52 on: April 26, 2009, 10:12:19 AM »
Good luck with the repair.
Personally if I happen to post a problem that were out of my field, I would like to see all options and self evaluate whether I have the capability to carry them out.
I figured that being an Engineer, albeit mechanical, you would have the ability to assess your own comfort zone in using any of the suggestions.

Offline simpson36

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #53 on: April 26, 2009, 10:34:45 AM »
NOsmoking,

I very much appreciated every suggestion and exactly as you point out, I realistically assesed my ability to devine a doable solution from all those cards laying on the table in front of me. While I can solder very well, if my life depended on my designing a circuit more complicated than a light bulb with a switch, I would be long gone . .LOL!!

As with my question about wiring limit switches at 24v and interfacing back to the 5v BOB, what I needed and could not get was someone to make me a schematic with part numbers. Given that, I can build things electronic. But I assess my ability to design electronic circuits as near zero and my abiltity to fry expensive components at near 100% . . ;D

The last thing I want is to put off people who are sincerely trying to help, but when there is conflicting information, I really have no way to determine which is correct. I was able to repair a variable speed drive by replacing the MOSfets, so I'm simply parrotting that proceedure with the power supply.  I take zero credit for fixing the controller. It was a FAQ on www.littlemachineshop.com that led me to try replacing the MOSfets. I can desolder an huge transitor and solder in an identcally numbered replacment, but I'm not foolish enough to believe I had ANY idea if it would work or why . . .  ::)

Anyway, my ability to run a 72V motor on a 72V power supply is relatively high, so that was the safe route to take, methinks, but I value every response, even if in the end there is no clear solution.
Re: Can two 36v power supplies be used in series to get 72v?
« Reply #54 on: April 26, 2009, 10:40:46 AM »
NOsmoking,

As with my question about wiring limit switches at 24v and interfacing back to the 5v BOB, what I needed and could not get was someone to make me a schematic with part numbers. Given that, I can build things electronic.


I could draw a 24-5v  interface up if you still need it, let me know the BOB.
 

Offline simpson36

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #55 on: April 26, 2009, 07:34:20 PM »
Nosmoking,

My particular problem was resolved in this way:

1) I found the interface schematic published on the Gecko website.

2) I decided to sidestep the whole 24V issue and go with photointerruptors instead of switches. I asked again on the forum for a wiring diagram for that  . .  I got good intentions and promises, but no schematic. I was, however, critisized for even wanting to use photointerruptors on the limits because mechanical switches are 'just as good'.  ::)

3) Peter Homann of Homann Designs was kind enought to review the interface schematic and catalog cut on the interruptor that I sent him and he provided a lot of information on how the schematic could be modified/simplified for use with the photointerruptors.

4) the entire issue became moot as when I totalled the cost of components at retail, it nearly equalled buying a prebuild indexer from CNC4PC, so I bough another of his excellent indexers (I use on on the spindle) which includes both the photointerruptor and the interface. When I get a chance I will install it as the X axis limit and just plug it into the BOB the same as the spindle indexer.

However, the limit switch wiring potentially causeing false e-stops seems to be a fairly common problem, so someone like yourself publishing a schematic on how to bump the voltage to 24V and interface that back to the BOB would be a great service to the CNC commumity here, methinks. If you do come up with something, I will be happy to host it and provide you a link to use for access. I'll even add a copyright notice on the image for you if you choose. That's not much, but it is at least something I can contribute.
 
To answer your question, I have two BOBs, the Gecko specific BOB fropm CNC4PC (C6G, or something like that I think) and the newest BOB from Homann Designs (for which I believe there is no documentation yet). They are just TTL 5v so far as I know. Let me know if there is any information I can procide you that would help with the design of the circuit . . within the limits of 'Electronics for Dummies' level where I am mired.







Re: Can two 36v power supplies be used in series to get 72v?
« Reply #56 on: April 26, 2009, 08:55:37 PM »
I think I know what you have in mind, but are you looking at something that can be constructed using discrete components, or using off the shelf industrial components where possible, obviously the former will be alot cheaper but require some electronic dexterity with a soldering iron.
I could also include for reference a costlier mostly pre-built solution which can be made somewhat cheaper by buying surplus etc.
A handy feature would be led indicator for input status?
N.


Offline simpson36

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #57 on: May 02, 2009, 11:31:24 AM »
Couple updates:

New transistors did fix the 36v switching supply. People considering these supplies from Keling should know that although they are listed as 'overload protected' the fuse blows only after the transitors have fried and shorted out.

My new 72V unregulated supply is in and working. Like getting new motors!  Amazing difference.  The little mill now shakes the whole friggin table it is sitting on!


As to the schematic to interface photointerruptors for use as limit switches, it turns out that CNC4PC makes a pre-wired optical interruptor setup with 6 sensors and a little contoller board all set up and ready to hook into the breakout. This is the hot setup. No muss no fuss, already figured out and built. Just needing to be installed on the mill. Here is the scoop:



Steve,

No, there is no simple way of connecting the sensors in series or parallel.  Maybe you might want to consider the C16: http://www.cnc4pc.com/Store/osc/product_info.php?cPath=29&products_id=183, which does what you are trying to do.

Arturo Duncan

http://cnc4pc.com

http://cnc4pc.com/live_help.htm


From: Steve Simpson [mailto:steve@thecubestudio.com]
Sent: Friday, May 01, 2009 4:01 AM
To: Arturo Duncan
Subject: Enquiry from CNC4PC

I have one of your indexers on my spindle as a tach. I just bougth another to use as a limit switch.

Mach3 can use one pin and a daisy chain of limit switches.

Quesiton: is it possible to daisy chain 3 NTE3100 interruptors to your indexer board for use as limit switches?

Offline Jeff_Birt

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Re: Can two 36v power supplies be used in series to get 72v?
« Reply #58 on: May 02, 2009, 11:48:48 AM »
Quote
People considering these supplies from Keling should know that although they are listed as 'overload protected' the fuse blows only after the transitors have fried and shorted out.

That should just NOT happen. I have tried a few times to get a better data sheet for their supplies but have not succeeded.
Happy machining , Jeff Birt
 
Re: Can two 36v power supplies be used in series to get 72v?
« Reply #59 on: May 02, 2009, 02:25:28 PM »

Quesiton: is it possible to daisy chain 3 NTE3100 interruptors to your indexer board for use as limit switches?[/i][/color]
I have built and test a three-in-series arrangement for somebody on another forum using similar devices H22A1's.