110vac to 12vdc-need schematic

[hamradioop]

hey all, first time poster. i am trying to make a 12vdc power supply using a playstation 2 power cord (not the ps2 slim). it has a 2 prong cord and a 7 amp max switch... can someone get me a schematic and parts list?
thanks all

 

[DerStrom8]

 

[hamradioop]

i meant the whole schematic... not just the transformer.

 

[DerStrom8]

i meant the whole schematic... not just the transformer.

Hahaha, I'm just messing with ya

it all depends on what you're planning on using it for. Simplest way to go about it is to connect the power cord to the primary coil of the step-down transformer (120v - 12v, if you're in the US, or 240v - 12v if you're somewhere else), and then connect the output to a bridge rectifier. If necessary, you can also put in some filtering caps.

Here's a basic circuit:


Just use a transformer with a 12v secondary rather than a 24v.

This is about as simple as you're going to get.

Regards,
Matt

 

[hamradioop]

i was going to use it for a battery charger... do i need a regulating circuit for that? BTW...i almost reported you for being "funny"... the moderators probably would of laughed at me though.

 

[DerStrom8]

i was going to use it for a battery charger... do i need a regulating circuit for that? BTW...i almost reported you for being "funny"... the moderators probably would of laughed at me though.

What kind of battery are you planning on charging?

You actually caught me in a good mood. I'm usually a cynical old coot

 

[hamradioop]

its a deep cycle marine battery. knowing that you can be "a cynical old coot" is good to know, so thanks for that.

 

[DerStrom8]

its a deep cycle marine battery. knowing that you can be "a cynical old coot" is good to know, so thanks for that.

Deep cycle batteries are usually LA or SLA. They're fairly rugged and can withstand a relatively wide range of charging voltages. I don't think you'd need any extra circuitry, except perhaps a fuse in series with the output for the sake of safety. I'm sure there are members here more experienced with battery charging than myself. Hopefully one of them can help.

By the way, just kidding about the old coot. Cynical sometimes, but you don't have to worry about me. In reality I'm usually a nice guy (at least I think I am--you'll have to ask around for that one )

Matt

 

[ronv]

How big is your battery (amp hours). How fast do you want to charge it?

 

[hamradioop]

its about a 130Ah SLA and i just want to trickle charge it. i am also planning on getting 2 7Ah batteries and charging them in parallel for a ham radio project.

 

[MikeMl]

its about a 130Ah SLA and i just want to trickle charge it. i am also planning on getting 2 7Ah batteries and charging them in parallel for a ham radio project.

For floating an SLA that large, you should use a well-regulated, constant-voltage power supply set to ~13.5V. Said supply should have a means of limiting its output current to a level that will protect the power supply from excessive heating (0.5A to 5A) when it is first connected to a discharged battery.

It should also have a LED (or voltmeter) to indicate that the battery voltage is within about 100mV of its final set point. This will give you a visual check that the battery has reached its float voltage. It also will tell you that the battery has a shorted cell, or its leakage exceeds the current capacity of your charger (i.e. the battery is discharging).

Here is a recent thread that talked about this.... Just double all the voltages.

You may also what to download and read the datasheet for the PB137. I think they put out too high a voltage for long term floating, but you can put a Shottky rectifier diode in series with the output to drop the battery float voltage from 13.7V to about 13.3V.

 

[hamradioop]

would an ampere meter in series take care of needing to measure current? where around coumbus ohio could i get a 120V to ~13.5V transformer

 

[MikeMl]

would an ampere meter in series take care of needing to measure current?

The meter will show visually what current is flowing into the battery from the charger. If you are trying to use that as a signal to control a charger, you will need to amplify the few mV across the meter shunt to a much larger voltage that could be used to control something.

where around coumbus ohio could i get a 120V to ~13.5V transformer

For float-charging, the transformer secondary RMS AC voltage should be sufficiently higher than the battery float voltage to allow for a voltage drop across the full-wave bridge rectifiers and to accommodate the drop-out voltage of the regulator IC. I have used these before.