Can anyone advise me on a project pls ?

[uktab]

This is my first project, so I hope it's relatively easy for a total newcomer.

My mum's HP printer power supply has gone missing in a move, so I thought I'd try to build one for her, as an official adapter is about £60 !

Here are the specs:

Input 50\60 Hz 800mA
Output 32V 844mA 27W

I'd love to know what to buy, which parts I can make myself if any, the tools I'd need, and which way round the tip should be wired on the bit that plugs into the printer, please !
I've found an old adapter that fits exactly into the printer, but it's the wrong Volts and amps output. Should I take it apart and adjust the components to match the printer's needs or start a fresh build ?

Thanks very much in advance !

[abuhafss]

Hi

The specs. of the original adapter are unique, especially the output volts 32V. This output is rare.
Could you please tell me roughly what was the size of the adapter? Then I can advice you.
Do you hang/connect it directly to the AC mains or it had some 2/3 pin lead?

[uktab]

Hi abuhafss - I found this link to an overseas website with a pic:

http://www.yottadeals.com/SearchResults ... =0957-2120

It's not a kodak like I thought but an HP printer. The hp part number (in the search field) is 0957-2120.

I'm in the UK and the cheapest I've seen is for about £35 - £40. My mum hasn't got much money and I want to learn how to build stuff, so I thought it would be a chance to try to build one.

The adapter plugs straight into the 240V AC wall socket. It may have a 2 to 3pin adapter to make it fit UK sockets but I can't remember.

Thanks !

[abuhafss]

You can find a simple easy to build a transformer-less power supply.

http://www.aaroncake.net/circuits/supply5.asp

For 220V you may change the values:

C1 = 1µF 400v
C2 = 470µF 50v
D1 = 1N5363B
BR1= DB104

If you cannot find BR1 you can use 4 pcs of 1N4004 rectifier diode to build your own Bridge Rectifier.

The light-weight adapters does not have transformers, which are heavy. If you want you can make this power supply with a transformer. In that case, the circuit will be little different.

Finally, be careful with the 220V AC mains and the polarities at the output pin.

[Simon (Webmaster)]

Please note that a transformerless power supply is not suitable for this purpose - there is no isolation between the input and the extra low voltage output. This type of supply is only suitable for powering totally enclosed circuits with no externally accessible connections or contacts. This is not the case here.

Most electronic equipment uses switch mode power supplies - these still have a transformer to provide isolation, however the mains input is converted to a higher frequency to increase the efficiency of the transformer (transformers are more efficient at higher frequencies and can have smaller cores). However given the complexity of them I certainly wouldn't recommend building one as a first project.

Your best bet would be a suitable mains transformer with 240V input, bridge rectifier and smoothing capacitor, and a LM317 regulator to give 32V output. A quick search brought up http://www.ehow.co.uk/how_6876575_build ... upply.html or http://www.circuit-projects.com/power-s ... lm338.html (the latter is over-complicated for your needs but you can leave out the meters and use a smaller transformer, as you only need 800mA, not 5A.

HOWEVER: Remember mains voltage is dangerous. Only attempt this if you are aware of the dangers and are able to produce a safe finished project. Please don't take any chances.

[uktab]

Thanks for the advice everyone. Very useful

Hopefully one day I'll know which components to use like you guys do !

[Weazel]

read dicksmith funway books and jaykar books and id look at ur local crud dealer these things are comon printers are every were just find the 1 that matches ur power needs and i wouldnt try make 1 with new parts it coast mre then to buy 1 us hobists destroy rubish to make our projects and mains is a no no for any beginer even 1 volt batery gear could kill u in the ideal circuit a flash cct in a camera produces 325 ish volt dc and i think it gets steped up to a few 1000 as well and transformerless psu is a big big no no in any circuit unless profound knowage of electronics and mains system is known and also auto transformers are out to