toroid voltagee

[m8kingit]

According to this schematic, I should have @40vdc ,but i'm measuring 76v dc at the drives . Can anyone explain? I've attached a schematic of the torroid i used.


This had 4 taps 4 x27vac, but they were in pairs and shared the center tap. I took one set of taps, wired both hots to the rectifier and used only the positive side and the center tap as my ground. I terminated the other taps.

I know i'm missing a point, hopefully someone will help me out. I saw a similar thread here a few months back, but I couldn't remember what the explanation was.

[123CNC]

the math says you likely have two 27Vac windings in parrallel, giving you 54 Vac secondary or ~76.4 Vdc

you would just use one winding to get 27.2 ac/38.4 Vdc rectified, wire one hot and one center tap

you could use the second set for a second power supply, separate bridge and capacitors

[Crevice Reamer]

If you need to be close to 40V, then use just ONE of the 27V AC taps.

CR.

[Al_The_Man]

Also for maximum VA you should parallel the primary's if using 120vac supply.
It sounds like you connected across the outer ends instead of one end a centre tap?
Al.

[m8kingit]

Yeah I know that's what it sounds like, lol i had someone from here tell me to wire it that way. I'm using gecko 201's, will this hurt anything .

I was under the understanding that the terminal connected to the unattached side of the bridge would be terminated, since i only used the + side along with the center tap.

Bottom line, is 76 volts too much for gecko 201's, will it cause them to run hot?
thanks
mark

[Crevice Reamer]

Gecko 201s can take up to 80V. But what about the motors?

CR.

[Al_The_Man]

Unless you are connected in the full wave centre tap mode, then you use half the bridge, or two rectifiers from the outer ends and the centre tap is your common.
You would still only get ~40vdc though.
Al.

[m8kingit]

Originally Posted by Al_The_Man Also for maximum VA you should parallel the primary's if using 120vac supply. It sounds like you connected across the outer ends instead of one end a centre tap? Al.

I see what i did i connected the red and the orange to the bridge and the outer wire as my ground, not thinking , lol.
Al, I did connect the primary paralell the 2 120's and the grounds.

Will this hurt anyhting the way I have this wired, or should i back the voltage down to where i thought it would be.? i'm using geckos201's

[Al_The_Man]

As mentioned, what motors are you using?
The red & orange to the bridge should give you ~40vdc?
Do not connect anything else.
Al.

[m8kingit]

Originally Posted by Crevice Reamer Gecko 201s can take up to 80V. But what about the motors? CR.

These are cnc masters motors, probably kelling 1200 oz/in 5 amps. but there is no more information to be had. Maybe I'd better'd back off the voltage. This is a cnc masters machine that i revamped the controller on, becasue of too many problems with the way they had it. These motors are not marked, nor do they have any specs.

[m8kingit]

Originally Posted by Al_The_Man As mentioned, what motors are you using? The red & orange to the bridge should give you ~40vdc? Do not connect anything else. Al.

Al I have the red and the orange attached to the bridge , then i used the postive side and the blue wire from the center tap, and this 76v dc is what I'm getting.

looking at the schematic i have attached, it looks as if i should have connected the red and blue to the bridge then used the orange as the ground( center tap) instead i used the red and orange at the bridge, which i guess expalins the higher voltage.

[Al_The_Man]

The red and orange should go to the bridge and terminate there. there should be no other connection to the secondary of the transformer.
The DC output of your bridge is the the +40vdc and -common marked on the bridge.
You only use the centre tap as common if using two rectifiers from the Red & Blue, then the orange is your -common.
It sounds like you are confusing the two methods?
Al.