Small transformer type

[jack0987]

Hi:

Could someone please give me a mouser part # for a transformer. I have a 24VDC power supply that has no 5VDC output which I need, also.

I would like to get a small transformer to drop the 24VDC to about 7-8 volts to feed a 7805 regulator to get the needed 5VDC. 2 amps max should be plenty.

Thanks.

 

[Diver300]

The 24 V is DC. You can't use a transformer on DC.

You can use buck converter, or just buy a separate 5 V supply.

 

[jack0987]

Hmm. Transformers do not work with DC!

Thanks. I would use a seperate small power supply except that the 24VDC and the 5VDC have a common ground.

Most have suggested just simply feed the 7805 with the 24VDC. Prehaps this is best.

 

[Diver300]

Thanks. I would use a seperate small power supply except that the 24VDC and the 5VDC have a common ground.

Mains power supplies are isolated, so you can connect the outputs how ever you like. Just join the grounds and they will be fine.

Most have suggested just simply feed the 7805 with the 24VDC. Prehaps this is best.

At 19 V drop and 2 amps max that is 38 W of heat. You need a big heatsink for that.

 

[jack0987]

Since I do not know much about this, my power guess is most likely overkill.

How about something like this.

7805

 

[Diver300]

Those are buck regulators, packaged to be compatible with a 7805. They will be fine up to 0.5 A.

They are a lot more expensive than a 7805, but they don't need a heatsink.

 

[jack0987]

Thanks so very much. The people who created the small boards I'm powering up are telling me that my 5VDC power requirement is very low and feeding a 7805 with a small heatsink will be fine. Looking through my parts box, I found two small clip-on heatsinks (1-1/2" x 7/8" x 5/8").

My concern was the additional boards I want to add later, so, I guess I could just add another 7805.