Help putting together Power Supply

[NeoMoses]

I bought all the stuff I need to build my own PS and I think I understand most of it, but I'm a little unsure about how to hook up my transformer(s). I bought 2 of these transformers:



I wasn't expecting there to be 3 wires on each side. I want to run 110V, not 220V. Should I just use the 110V and the common on one side, and the corresponding 12V and common on the output side?

Also, I've got 2 of each part (xformer, rectifier, caps). Would it be better to wire 2 completely different power supplies and then run their outputs in series to get the desired voltage? Or should I wire the Xformers together internally for the higher voltage?

Edit: Link Fixed for Pic.

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[ToyMaker]

NeoMoses

Connect the 110 thru fuse(s) and switch to the red leads (tape off the black). On the output side connect both blue leads (tape off the yellow) to your bridge retifier. Retifier to filter cap.

That connection will give you 12V out and the transformer will be under less stress than if you only use half the windings.

robotic regards,

Tom

[HomeCNC]

ToyMaker, Are you saying to use the 220 input but connect it to 110? This is the same transformer that I used in my first servo box. I have a connection diagram on my website under the building the servo box. I used the black and the 110 Red wire for the input. This transformer should give you close to 36VDC @ 10 Amps when you are finished.

http://www.homecnc.info/servo%20box.pdf

[ToyMaker]

Jeff:

If you connect 110V to one side of the primary (1 side and center tap) and take the output from one side of the secondary (1 side and center tap) you'll see about 16-17 V peak (Vpeak = Vrms X 1.4). The 12V rating written on the transformer is an rms value (Vrms = Vpeak x 0.7).

Taking the output across the whole secondary winding (ignoring the center tap) would give you 24Vrms. The 36V you read is the peak value and will droop when loaded.

There may be a typo in the wiring diagram; either the fan is ac or it is connected wrong.

robotic regards,

Tom

[HomeCNC]

Yes, 24V will give you 33.6 VDC. This is why I had a toroid built for me on my second servo box. It outputs 26VAC.

You are correct about the fan. I have a mistake in the drawing. It was a DC fan so I need to change the wiring.

[peter_cassar]

Hi All,
This is my first post. I'm building a controller box for a small lathe. I have a 36V DC 9A SMPS for my steppers,this works fine. I wish to use a 24V 40Amp SMPS for spindle motor power, this works great directly running the 24V DC motor but when I pass this through a PWM speed controller my SMPS shuts down. It doesn't seem to like a switched load. What could be wrong here? If I use my 36V SMPS regulated to 24Volts the DC spindle motor works with the PWM speed controller perfectly. In fact the 24V 40A SMPS doesn't work at all with my stepper driver board or the PWM spindle controller (switched loads). Is there something I can do to the 24V SMPS to remedy this or should I look for another solution? I have a 24V 10A SMPS on order for the spindle controller but I want to keep this simple. I can't use the 36V supply with both stepper drivers or spindle controller as there seems to be excessive current drawn even though my 24V motor is only 100Watts , 4Amp max stall current, it's like a dead short. Steppers are under 2Amps each for the two I have. Steppers and spindle motor work great seperately but when connecting the boards in parallel to the 36V power supply my ammeter shows something like a dead short and I'll treat it as such until I figure out what's wrong.