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### Author Topic: Can two 36v power supplies be used in series to get 72v?  (Read 31600 times)

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#### simpson36

• 1,369
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #40 on: April 24, 2009, 02:52:02 PM »

This is my new power supply. So far, I know is is unregulated, I think it is toroidal, and I still have no idea what linear means.

"The reason I was asking is if you had a linear supply that had a Toroidal transformer, this looks like a Large donut BTW, you can quite easily take off windings to tailor it to the voltage you need."

How does one go about finding and taking off the 36V?

#### NosmoKing

• 238
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #41 on: April 24, 2009, 03:18:07 PM »
That looks like the AnTek version, I buy my Toroidal transformers from him, like the one in the rear of the picture.
Linear has come to be the description for any  transformer-bridge-capacitor supply, but technically it would normally have a series pass transistor or? for linearly (non-digital/switching) control of the DC output.
The tailoring of Toroidal transformers is fairly easy, you have to know the turns/volt to know how many turns to take off, say you wanted to reduce a winding by 10v output and the transformer had 2turns/volt, then removing 20 turns would do it, turns can also be added to increase the output also. Or you can add a completely separate winding, as long as you do not exceed the total VA of the transformer.
If you want to find out exactly before hand, then wind on a small conductor of 10 turns and measure the AC, the math can then be done.
« Last Edit: April 24, 2009, 03:20:55 PM by NosmoKing »

#### RHOLLIDAY

• 8
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #42 on: April 24, 2009, 11:04:07 PM »
You can use a voltage doubler circuit if your transformer has extra current capacity.  Get some 40V 22000 mf capacitors , remove the +wire from the Bridge rectifier and connect it to one side of the AC transformer lead this will be your 36v positive lead  . Connect the  minus side of the new capacitors to the +side of the old capacitor connect the + terminal of the Bridge Rectifier to the + side of the new capacitors this will be your 72v line.

#### simpson36

• 1,369
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #43 on: April 25, 2009, 01:08:41 PM »
Thanks for the info.

Situation has changed and now I need to run a 36V motor off the 72V power supply. Can that be done in a similar way with a 'votage halver?"

#### RHOLLIDAY

• 8
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #44 on: April 25, 2009, 01:19:59 PM »
If you use the voltage doubler you will have both 72v and 36v outputs.

Robert

#### HimyKabibble

• 1,687
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #45 on: April 25, 2009, 03:19:34 PM »
If you use the voltage doubler you will have both 72v and 36v outputs.

Robert

He has a 72V power supply, not a 36V supply.  He doesn't need a 144V supply....

Regards,
Ray L.
Regards,
Ray L.

#### Dan13

• 1,208
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #46 on: April 25, 2009, 03:28:01 PM »
I think if he can find a zener diode that can handle this voltage at the current he needs, then it would be the best solution...

Daniel

#### HimyKabibble

• 1,687
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #47 on: April 25, 2009, 03:36:54 PM »
I think if he can find a zener diode that can handle this voltage at the current he needs, then it would be the best solution...

Daniel

That would be one bloody HUGE Zener diode, and it would be *constantly* dissipating as much heat as the motor running full load.  There is no easy way to get 72V down to 36V at the kind of currents required by a motor.  It requires a regulator.  The only viable solution is to buy a suitable 36V power supply.

Regards,
Ray L.
Regards,
Ray L.

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #48 on: April 25, 2009, 05:24:02 PM »
If it has a toroidal transformer then there is a chance it has two 25v outputs in series.
Now I know very little about this kind of stuff but would taking a tapping from one of these secondaries and then rectifying and smoothing not do the job? Of course it may have two 50v secondaries wired in parallel or indeed just have a single secondary but most toroidals I have seen have the two.
Then again its probably just as easy to build a second power supply and not have to worry about exceeding any limits..
Hood

#### NosmoKing

• 238
##### Re: Can two 36v power supplies be used in series to get 72v?
« Reply #49 on: April 25, 2009, 05:34:49 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.