DC-AC converter circuit

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#21
that would be great! And yes, I have two proto boards (those things come in handy😉 )

really only one decent one, the other is on my old radio shack electronics learning lab.

my skill level has progressed rapidly from this project

http://www.diyaudio.com/forums/showthread/t-59999.html

so yeah, still kinda a beginner, but I know a lot already 🙂

still gots much more though! And thanks for any help, I will see if I can get ahold of some more samples here sometime so I can try those chips.
 
#24
A few things you will need before you start trying to build your supply.

You've already got a proto board I'm not sure of the size but I'll assume it's the same as mine which is small.

You'll also need these things:

PWM controller sg3525 from whomever, I think Fairchild semi also has one called uc3525 but I've always gotten mine from ST Microelectronics.

http://www.st.com/stonline/products/literature/ds/4286.pdf

2 or more low rds on mosfet's, I use stp60nf06's also from ST, good bang for the buck.

http://www.st.com/stonline/products/literature/ds/7559.pdf

4 to 8 high speed switching diodes capable of handling your designs power requirements. I like the fep16dtd's from Fairchild they are diode pairs mounted in a to220 case and are perfect for this application. There are many others though that would be well suited for this but again these are the ones I've always used.

http://www.fairchildsemi.com/ds/FE/FEP16DTD.pdf

A couple low esr switching capacitors like the lxy series from www.chemi-con.com

http://www.chemi-con.com/files/LXY .pdf

Also, you'll need a ferrite toroid core. I like the 43615-TC only because when I started building these this was referenced on the site I mentioned early. Unfortunately, I don't have any right now so I'll be using and alternative that was salvaged from an atx psu.

A heat-sink, not to big but big enough to mount all your to220 components

And your standard resistor's cap's and stuff. There are many sources to order this stuff from and I'm sure you have some already, but just in case here's a few, www.arrownac.com www.mouser.com www.newark.com www.futurlec.com (not USA), I don't like Digikey there prices are insane on allot of items.

Here's a pic of the key items you'll need.

I'll start assembly tomorrow.
 

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#26
wow! Thakns for helping me with this. ( btw, nice work on the amp 🙂 )


ok well I just recieved yet another sample from ST today in the mail.. that I ordered months ago.. I don't want to wear out my welcome with samples, so I'll try fc like you said. I have to wait untill monday of cource (buisness hours.)

the caps I can get at the Shack, I don't have 35v ones right now, just a 25v and a slew of dinky 6.3v ones from a computer psu. I do have a ferrite ring, I don't know how big though. How big is yours? Mine came out of a computer psu, I'm sure I can get ahold of another psu sometime to see if I can get diff sizes though. I MIGHT have the diodes, or something similar ( cpsu as well) but I think I will have to order those.

your protoboard looks like the one on my radio shack learning lab. I have this one also http://esssales.com/images/global-images/prototyping/pb-10.jpg
its a LOT nicer and has screw terminals/bananna jacks for power in and out, as well as 8 seperate power rails.


Will I need any high-wattage resistors for this project? I mostly only have 1/4 watt ( I got the Shack's bag of 500 assorted, so I'm pretty well off on the value part.)
🙂
 
#28
Hi speakerdude,

I'm not sure but I don't think Radio Shack sells the low esr (effective series resistance) capacitors you'll need for reliable operation. Standard capacitor's will quickly fail or at best give erratic operation from the high switching frequency, around 30-35khz.

I really recommend investing a little in the proper components.

These caps will be adequate for you supply needs. And they’re only $.50 us each.

http://www.mouser.com/index.cfm?&ha...*lxy25vb102mll*&Dk=1&Ns=SField&N=110&crc=true

I also have the larger proto board and will use it instead. It’s a little scarred from use but it’s functional.

The only large resistors needed are for the snubber circuit. These also are very cheap from mouser $.39us for 1 or $3.10 for 10. It would be possible to use less then adequate resistance for prototyping purposes say like wire three 220 ohm resistors in parallel to get a 73 ohm 1 watt (slight exaggeration) resistor. But you need to two of these so that’s 6 resistors, clutter.

As for the STP55 mosfets these will be more then adequate for our supply. Quite a coincidence with these fet’s they are very similar to I almost used these on my first supply.

You will also need some small value metal film caps for the timing circuits and supply bypassing.

You need some of these

http://www.mouser.com/index.cfm?han...uctid=356244&e_categoryid=497&e_pcodeid=01426

And some of these

http://www.mouser.com/index.cfm?han...uctid=380126&e_categoryid=497&e_pcodeid=01426

If you have these already then great if not then they are also cheap and you can get it all from Mouser.

The core I’ll be using is 1.25” o.d. X .9” i.d. X .6” tall it was a mentioned earlier pulled from an ATX PSU which was working when I decided to donate it to research.

Core materials are important but I’ve used a verity of unknown cores all with some degree of success, I just wouldn’t trust it to run anything of value.

Let me know how you make out .
 
#31
hey I wanted to thank you for your time and help, I have been swamped this week. Right now my room is kinda torn apart ( we converted it from a garage) so I'm still in the process of getting it organized again. On top of that, tomarrow is my brithday , and I have physics class to take from 10-2, and then from 2-4 a friend is coming over. Then I have somthing on thursday, and on FridayI have my birthday party. Hopefully I will have time to try and order some samples tomarrow when I get back, and once I get those then we can start the project. I'm also getting another old pc psu to rip apart and scavenge parts from.

again, thnks for your willingness to help! 🙂]

EDIT:

can you tell me what values of resistors I need so I can double check? I have some 1 watt resistors I pulled from some circuits I can look through for the larger wattage ones.
 
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