Need urgent help with TDA1554 PSU !

[Dmeister]

Hello everyone. I'm very new to diy audio and making amps and such, but i've decided to give it a go and try building a 2x22W stereo amp with the TDA1554 Chip. Now i have all the parts needed but i don't have a PSU yet. Since i don't have any money to buy a new one, i was thinking of using an old AC-AC converter i have. It converts 220VAC to 12VAC 4.2 amps. The circuit however, needs DC current and not AC and it needs 5 amps to operate on full power. Would this AC-AC converter i have work ? Is the current enough ? Also, how would i convert the 12VAC 4.2 amps to DC current ?

[mastermind88]

i don't think is a good idea to use that AC-AC converter, for two reason:
1) 4.2 A are too under the requirement of your circuit
2) the AC/DC converter (the rectifier module) introduces other losses, so you would have few than 4.2 A.

I think in this forum, even if i'm new, there are alot of AC/DC rectifier schemes to work on, but if you need more info i can find some reference on it.

[pacificblue]

By AC-AC converter do you mean a transformer? In that case you need a rectifier bridge or 4 diodes and a big smoothing cap with 2200 µF or more. Small snubber caps across the rectifier are recommendable on top of that.

12 V AC leads to ~16-17 V DC ± regulation and mains tolerances, so you should consider to use a transformer with a lower secondary voltage. You must also take into account that there are no 220 V mains anymore and your 220 V transformer connected to a 230 V grid will give you a higher secondary voltage of 12,5 V to begin with, resulting in ~17-18 V DC, again ± regulation and mains tolerances. While such a car radio amplifier is quite rugged, overvoltage could shorten its life expectancy, if you live in a region with healthy mains voltage.

[Dmeister]

Originally Posted by pacificblue

By AC-AC converter do you mean a transformer? In that case you need a rectifier bridge or 4 diodes and a big smoothing cap with 2200 µF or more. Small snubber caps across the rectifier are recommendable on top of that.

12 V AC leads to ~16-17 V DC ± regulation and mains tolerances, so you should consider to use a transformer with a lower secondary voltage. You must also take into account that there are no 220 V mains anymore and your 220 V transformer connected to a 230 V grid will give you a higher secondary voltage of 12,5 V to begin with, resulting in ~17-18 V DC, again ± regulation and mains tolerances. While such a car radio amplifier is quite rugged, overvoltage could shorten its life expectancy, if you live in a region with healthy mains voltage.

I'm in a region that doesn't really have healthy mains. Thanks so much for your help but could you tell me what diodes to get or if you can draw me a schematic ?

[ampimp]

Hi
It would be a very good idea to do a little reading about eletronics basics before you attemp to build an amplifier. you are about to play with mains voltages . im not sure if i can post a link but i will try.
Tutorials, Electronics made EASY, Williamson Labs this site is very good and is easy to understand .
I hope this will help you in your quest.
Regards Ian

[pacificblue]

The diodes should be able to pass the maximum current which is 16 A for the TDA1554. The voltage rating should be bigger than 4,5 times Ueff, i. e. more than 60 V for you transformer.

If you don't know how a rectifier is made from 4 diodes, you'd rather use a bridge rectifier. They are usually cheaper and you don't have to worry much about the connection.

[Mashoni]

Originally Posted by Dmeister

Hello everyone. I'm very new to diy audio and making amps and such, but i've decided to give it a go and try building a 2x22W stereo amp with the TDA1554 Chip. Now i have all the parts needed but i don't have a PSU yet. Since i don't have any money to buy a new one, i was thinking of using an old AC-AC converter i have. It converts 220VAC to 12VAC 4.2 amps. The circuit however, needs DC current and not AC and it needs 5 amps to operate on full power. Would this AC-AC converter i have work ? Is the current enough ? Also, how would i convert the 12VAC 4.2 amps to DC current ?

TDA1554 WAS MADE FOR CAR audio application voltage range is from 9 -18volts max with maximum current at 10Amps.you can use a laptop charger most have 15Volts and 5amps or you may use a 12vac transformer when rectified to give you 14volts 5amps.do not try and experiment on any other form of power supply.I believe now you have got the hang of things to to with amp circuits try and DIY a TDA2050 AMP,HERE IS THE SCHEMATIC FOR SINGLE SUPPLY,if you want in stereo mode then build 2 of the same circuit.enjoy

[Dmeister]

Ok, yesterday i made a rectifier circuit from 4 diodes that i had laying around. The rectifier is properly converting the AC to DC (i tested it with an LED and a resistor). The only thing that i don't know is how many amps of current it gives off now since my shitty multimeter doesn't measure current. But thanks for the replies everyone.

[pacificblue]

The current is determined by the load, not the rectifier. Look up the datasheet for the diodes you used and it will tell you the maximum voltage and current rating of those diodes.

[Dmeister]

Originally Posted by pacificblue

The current is determined by the load, not the rectifier. Look up the datasheet for the diodes you used and it will tell you the maximum voltage and current rating of those diodes.

I can't really find the datasheet since i just ripped them from an old radio i had lying around so i don't know the model number or anything