What is the current rating on each of the secondary windings?

 

So the new parts on the shopping list include (3) lm337's and (3) 2n2955's right? If I use the 8vac coil to make a 5vdc regulated supply I have some DF01m 100prv, 1a (4-pin DIP) FW bridge rectifiers I could use for it. What size filter caps should I use on it? And could I use another lm317 to regulate it?

You could, but a 7805 will use fewer parts. 5V supplies tend to be all about the current, and you'll only need about a 16V cap, so make it a big one!

 

What is the current rating on each of the secondary windings?

Im not sure how to measure it. I have a really good dmm and a velleman o-scope... The transformer came out of a Marantz power amplifier so im sure it will give me the 4a I want.. If I have enough equipment to measure it, And you give me an idea how to I would be happy to do it. Ive wondered this myself.

 

You could, but a 7805 will use fewer parts. 5V supplies tend to be all about the current, and you'll only need about a 16V cap, so make it a big one!

I believe I have a 7805 in my parts box.. Got an example circuit for it?

 

I drew up what I think needs to happen. I haven't added any pass transistors in it yet. Because im not sure if they are needed and im not real sure where they belong. Im aware this is unfinished and probably has more than a few errors.. sorry its on paper.. still trying to figure out LTSpice.. And I don't know how to make custom components in eagle..

 

I would scrap your circuit for starters - too complicated.

We began with a basic +ve and -ve unregulated power supply design.
The next step is to add +ve and -ve adjustable regulators.

TO3 posted a simple circuit using LM317 and LM337 in post #32. That is a good starting point until you figure out the amperage of your windings.

 

I would scrap your circuit for starters - too complicated.

We began with a basic +ve and -ve unregulated power supply design.
The next step is to add +ve and -ve adjustable regulators.

TO3 posted a simple circuit using LM317 and LM337 in post #32. That is a good starting point until you figure out the amperage of your windings.

that's the circuit I went off of except I added the extra 2 of each regulator like the schematic I posted in post #1 to add more current capabilities. I would like to have 4a available. from the datasheets ive read a single lm317 or lm337 ill only be able to get 1.5a.. if theres an easier way im willing to change it all.. that's why I posted it is to get everything right before I build it.

 

And im working on figuring out the amperage of my windings now. The only reason I was even thinking of the lm 317'a and 2n3055 pass transistor is because I had a bunch of both in my parts box. I have a really esco parts shop in my town and can go get just about anything I want. The shop I work for has an account there and I get about a 50% discount on everything except tools.. I only paid 4 dollars apiece for my 10.000uf 50v filters caps and ive seen them elsewhere for 15 bucks.. So I can buy whatever I need pretty cheap. thanks for the advice.

 

Would the circuit in post 32 provide me 4a with a pass transistor? I have 4 2n3055's and I just picked up 4 2n2955's today.. they were cheap and im sure ill use them in a project at one point. And I thought using the NTE996 to control the lm317's was a good thing?

 

Yes, but let's tackle one thing at a time.

 

Yes, but let's tackle one thing at a time.

Right on.... Ill have some current measurements from my transformer sometime tomorrow. Then I guess we will know exactly what I have to work with.. thanks again.. I just want a nice reliable adjustable power supply with some current...that's all.. But I want the experience of figuring it out and building it myself...

 

transformer testing coming soon.. just wanted to bump this up and keek it alive..thank you

 

I was told in an old thread here that the NTE996 ( it an op amp right?) would be better to use to control the adj. leg of the lm317 and lm337. So would it good if I add that to the circuit in post #32? It's supposed to correct a gain issue?

 

I haven't given up on this.. had a busy couple days at work. im experiencing a few technical difficulties with my ac delivery to the transformer.. post back soon.. any explanations on the question I asked in post #53?

 

just trying to keep my thread at the top and alive,, but im in the process of testing the transformer at this very moment.. so I should have some numbers up real soon,,, I hope after that MrChips could point me to the proper circuit and I can find out my current limitations for my PSU.... and to3metalcan has been a huge help here also......Thanks to everyone who is helping me...

 

For the positive side, look at the LM338. This is good for an adjustable 5A positive supply.

Take a look at this:

http://www.bristolwatch.com/ele/lm317.htm

 

I I use the lm338, what would I use for the negative side,, I want to buy all these together?

 

Look at LT1085 for positive 3A supply and LT1185 for negative 3A supply.

 

Ive been testing my transformer in another thread, and even though im not completely done testing, I think im safe for the 0-24v 4a adjustable supply...So now its on to the regulator circuit. I have some lm317/337's a couple NTE996's a few 2n3055/2955's.....Ive got a few small ic type 2a rectifiers.. and other things I will implement later on in my build.. I want to be clear that I am willing to purchase other IC's and whatnot,, im not entirely stuck on the 317/337 driven by the NTE996's with the 2955/3055 pass transistors,, although im kinda going for a retro look and they would fit the description.. however I intend to use this supply often so it has to function properly...
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The only reason I keep going back to this arrangement is because I use AStron supplies at work and they appear to have similar configurations.. On my 60a adjustable voltage one I use at work, I can see the power transistors on the case with the big heatsinks.. It is a very reliable PSU, and ive hit it hard many times without a hiccup..