Power supply design help - newbie question

[Neptune769]

power supply 7805 7809

Hello Everyone,

I am new to this forum and need some help with a power supply design. I know just a little about electronics. I need to build a power supply with an input of 12 - 18vdc. and an output of 5vdc AND 9vdc. Could I just use a 7809 and a 7805? Or do I need to add some capacitors, resistors & diodes? If I could get or find a schematic I can build it. I also don't know what values I would need. I just can't design a circuit. I need to keep it compact. It would be on a board 1.6" square with a RJ45, a 14 - 20 pin IC a 3x2 header and a 9 pin flat flex connector. The components can be the larger size SMT. I would prefer US part numbers. Any help would be greatly appreciated.

Regards,
Dennis

 

[Altafhal]

vk-s234 schematics circuits

You can use 7809 and 7805.
For both ics you have to connect capacitors.
At input use a large value capacitor ie 10 uF and at output use small value value ie 1 uF.

 

[Audioguru]

Re: Power supply design help

You can't make a regulated power supply without thinking about how much output current and how much cooling is required.

 

[angy]

Re: Power supply design help

What u can do is use LM2576 (12V)
It gives a regulated o/p of 12V.
This 12V is given to two regulators (Lm7805&Lm7809)

 

[siongboon]

Re: Power supply design help

Maybe you can share what you intend to do with the power supply.
Supply current is also very important.
If the current you need is 0A, a simple voltage divider would be enough to be consider your power supply.

7805, 7809 would also be enough.
LM2575, LM2576.

Each type of IC regulator has their current limit.

Like the size of a water pipe,
there is a limit on the water flow rate if the pipe is small.
This is so call the current.
Larger wire size can carry more current.
Small wire may also carry the same current at the expense
of increase temperature & resistance.
When too hot, the wire will just burn off, just like what a fuse do.

You may like to visit this website for
a bit further information on voltage regulator.
It may help provide you with further information
for your learning.
**broken link removed**

Best Regards,
Siong Boon
MODERATOR - SIGNATURE LINKS ARE NOT ALLOWED

 

[ammarabbasi]

Power supply design help

R u stepping down from 110 AC. or u want to built a dc to dc converter . you can use voltage division irrespective of complications.

U said 12-18 , use a variable resistor here to get voltages between 12 and 18. prior to this you should have 18 volts .

i think 0ne or couple of variabe resistor could do the job . when applied in series will limit the voltage and when applied in parallel will limit the current.

 

[hamid_sarab]

Power supply design help

dear also u can find datasheet of IC such as 7805 by type in the google 7805+datasheet and obtain free

 

[fsmyth]

Re: Power supply design help

Do something similar to:
**broken link removed**

 

[Neptune769]

Re: Power supply design help

Hello Everyone,

I'm sorry that I haven't replied sooner. I don't check this forum very often. For some reason I never got notified about the replies to my post. I even have the "Notify me when a reply is posted" box checked. Anyway. I have found schematics that I am using now. The project is a DC to DC converter. I am going from 12vdc to 5vdc 5 amps and also a separate one on the same board 9vdc 2amps. It is going to be used for a Pan/Tilt unit and cctv camera. The board also has an Atmel Attiny44 to control the camera (zoom, Iris & Focus) and servos for Pan/Tilt. The camera is a Hitachi VK-S234. Now all I have to do is wait on an order for Press N Peel so I can make the board. I do appreciate all the input. If anyone would like to know more about my project feel free to contact me at neptune769@gt.rr.com

Regards,
Dennis

 

[Hao.J]

Re: Power supply design help

You can't make a regulated power supply without thinking about how much output current and how much cooling is required.

...and how clean you need the power supply to be.

they are key points for designing a power supply .

Hao: