# Transformer blues....Pricey buggers HELP!

#### kalikid1210

Joined Jul 15, 2008
21
Here is the schematic (CLICK on the image, which will open in a new window) for a power supply I am using to power a 24Vdc, 135W, 10A scooter motor.

I went to digikey.com and the lil beast was over 50.00! Please tell me that there's a more economical way.

But, yes there's a but, I would be interested in a pricey, up to $75.00, transformer if it were very small. In other words the smaller the better. Size is a definite concern in this PS's construction. Is it possible that it could the size of a pack of cigarettes? I don't smoke btw...yet. Would a toroid transformer make the grade? #### Audioguru Joined Dec 20, 2007 11,251 Your filter capacitor is much too small for a 10A load. It will also cost a small fortune. My powerful appliance motors are AC and run directly from the mains without a transformer, rectifier and filter capacitor. #### tkng211 Joined Jan 4, 2008 65 If you wanna have a small sized one, better get a switching power supply instead of using steel core transformers. #### SgtWookie Joined Jul 17, 2007 22,201 ...I am using to power a 24Vdc, 135W, 10A scooter motor. One of the above numbers is incorrect. A) 135W @ 10A = 13.5V B) 24V @ 10A = 240W C) 24V @ 135W = 5.625A. Pick one; A, B or C. I went to digikey.com and the lil beast was over 50.00! Please tell me that there's a more economical way. MPJA to the rescue; 24V @12.5A for under$25 in a switching supply:
http://www.mpja.com/prodinfo.asp?number=17429+PS
Larger than you want, but you can't have everything.

But, yes there's a but, I would be interested in a pricey, up to \$75.00, transformer if it were very small. In other words the smaller the better.

Size is a definite concern in this PS's construction. Is it possible that it could the size of a pack of cigarettes? I don't smoke btw...yet.

Would a toroid transformer make the grade?
Toroidal transformers are very prevalent in switching supplies. They can make them small because they operate at much higher frequencies than 50Hz/60Hz. However, you'd have to design and build a complete switching power supply, which would be a lengthy, complex and expensive task for a novice.

#### jj_alukkas

Joined Jan 8, 2009
753
If you wanna have a small sized one, better get a switching power supply instead of using steel core transformers.
A switching mode power supply at 24V 10A can never be made at the size of a cigarette pack though it will be a smaller than the corresponding transformer.And as SgtWookie stated, building it isn't easy either.