Hi, folks.
I'm working on a bench top power supply. I'm combining an instructible and the basic voltage design from Forst Mims' GSiE. So far having lots of fun and general success (burnt up a couple of small parts.)
Stuck on one issue. I want to power 2 small 12v DC fans. They come with no specs. I don't yet know how to draw circuits so I'll describe mine.
wall plug -> 10A fuse -> switch -> 25.2V 2.0A transformer -> bridge rectifier -> (2) 2200uF caps in parallel -> SH-PWS1 buck converter -> .1uF cap -> output posts
First, I used a L7812 in parallel with the last 2200uF cap. Fan didn't run until I powered off and then it ran for 1 sec (I guess as the discharging caps reached just the right point?) When I measure voltage after the L7812 without the fan it measures 12.0V. (Yay!) When I attach the fan (which won't run), I get 1.2V. Is the fan acting as a resistor?
To make sure I had a good fan, I hooked up the fan to the output posts and set voltage between 9.0V and 12.0V. It ran fine and sped up / slowed with the changes in voltage.
What am I doing wrong? Any help appreciated.
Carlo
I'm working on a bench top power supply. I'm combining an instructible and the basic voltage design from Forst Mims' GSiE. So far having lots of fun and general success (burnt up a couple of small parts.)
Stuck on one issue. I want to power 2 small 12v DC fans. They come with no specs. I don't yet know how to draw circuits so I'll describe mine.
wall plug -> 10A fuse -> switch -> 25.2V 2.0A transformer -> bridge rectifier -> (2) 2200uF caps in parallel -> SH-PWS1 buck converter -> .1uF cap -> output posts
First, I used a L7812 in parallel with the last 2200uF cap. Fan didn't run until I powered off and then it ran for 1 sec (I guess as the discharging caps reached just the right point?) When I measure voltage after the L7812 without the fan it measures 12.0V. (Yay!) When I attach the fan (which won't run), I get 1.2V. Is the fan acting as a resistor?
To make sure I had a good fan, I hooked up the fan to the output posts and set voltage between 9.0V and 12.0V. It ran fine and sped up / slowed with the changes in voltage.
What am I doing wrong? Any help appreciated.
Carlo