Power Supply

[pongkratz]

hello guys,i'm a newbie here..i am a student from philippines.we have a project in electronics..cn u help me how to make a simple power supply..thx...

 

[giaosucan]

you can use 7805 or LM317 to design power supply circuit

 

[Hero999]

https://www.repairfaq.org/sam/laserhsc.htm#hsctoc

 

[ZIGGY_DAN]

This is a nifty little variable power supply using a L7805, thats right a fixed voltage voltage regulator, i have never made it but in theory it will work and could be built to fit into the palm of your hand, it's output voltage is variable from 6.5-35VDC, with a 35VDC input, i'm not to sure it would work well at the lower voltages due to the enormous voltage it has to drop and therefore the enormous amount of heat it would produce, a good heatsink is required. If you wanted a good reliable power supply get a LM317, i have a few, if you need a diagram search on google for the datasheet, the LM317 costs about £1 and requires few external components to operate reliably.

hope this helps

 

[pongkratz]

thanx 4 ur reply guys..

 

[Dr.EM]

Adapt this to your needs:

**broken link removed**

 

[Hero999]

This is a nifty little variable power supply using a L7805, thats right a fixed voltage voltage regulator, i have never made it but in theory it will work and could be built to fit into the palm of your hand, it's output voltage is variable from 6.5-35VDC, with a 35VDC input, i'm not to sure it would work well at the lower voltages due to the enormous voltage it has to drop and therefore the enormous amount of heat it would produce, a good heatsink is required. If you wanted a good reliable power supply get a LM317, i have a few, if you need a diagram search on google for the datasheet, the LM317 costs about £1 and requires few external components to operate reliably.

hope this helps

That won't work, it'll just give Vin*(Position of VR1) + 5
Where "Wiper position of VR1" is 0 with the wiper at 0V and 1 with it at Vin, except it'll never reach Vin, the maximum setting would be Vin - 2V

 

[HiTech]

Pongkratz didn't state what output voltage(s) are required, whether fixed output or variable. So for the sake of extreme simplicity, simply take an AC line cord and solder a diode to the "hot" leg of the AC line and you'll have rectified DC voltage with no regards to AC filtering. Yes, it still qualifies as a power supply and that's what he asked for!! (can you imagine the look on the teacher's face as he strolls on up to the desk with a small diode soldered to a line cord saying, "here's that simple power supply you requested".

Now if he wants to receive an A for his project, then I'd suggest something along the lines of a well filtered or a nice simple variable type as what was posted above in another reply.

 

[Hero999]

I agree, look at the link I've posted in the third reply to this thread. I was hoping him to have come back and said something like "that's no good I don't want a laser power supply, I just want a small DC supply for my project", or for all I know he could've wanted a laser PSU and used it.

 

[HiTech]

He won't need a laser pwr. supply in the Phillipines since all they have there are those keychain mounted ones that run off of three button cells!

 

[Paul Obrien]

The 7805 power supply above would have the heatsink above ground potential, I know from the ones I've built it can be a pain.

 

[oldtimer]

Try sticking a pot between centre pin and ground on a 78 series and see what you get.