Power Supply, new design.

[Hank102938]

I've come to the conclusion that a linear regulator isn't my best bet, or if it is, I must have missed the memo.

What if I asked you this, forget all the other stuff we've been over...
I have a 25VCT transformer and full wave rectifier. How can I build a variable power supply [close to] 0V to 24VDC at min. 1A output? With built in analog volt meter, oh, and throw in variable current limit with an analog ammeter too.

SURELY somewhere there is a design for something like that! I've spend at least 24 hours total trying to figure this thing out... And you know, I'm going to be pretty -insert choice words here- off if I don't end up with something that works. At this point I'm not too worried about what I have to spend (within reason) to make it work, I just want something I can say I made and that works. I'm counting on your help and reply, but please, excuse my anger, this:

The calculation uses grade 4 simple arithmatic.

is not the reply I'm looking for. I know something, just not everything. If you've got any useful suggestions than please, let me know. Otherwise, I truly have appreciated everyone's help and good day to you... or night, or what ever time it is where you might be. Thanks.

 

[ronv]

Lab Supply

Hank,
Here is a schematic for a 0-24 volt 1.5 amp + supply with provision for meters (digital). I'm thinking about building this for myself. It is not simple. Do you think you could do it?
Do you have a voltmeter and "stuff"? It's probably about 30 -40$ plus meters. Let me know if you want to try it and I'll price it out.

 

[Hank102938]

Well I did get what I asked for. But it looks like a lot of work.... of course the time spent trying to fix the old design is considerably more than what it would take to solder this thing up... I do have an cheap multi meter, but I don't think the ammeter part works. (either that or I don't know how to test current) or I could get the same meter for $10 or so. Just a few questions, can I still use my current transformer, can I use perfboard or will that just make it 100x harder and are you sure this is about as simple as its going to get for what I want? If you can price it out with out the meters that would be great, but don't waste your time on it, I'm just as capable of doing it...

EDIT: Came up with a few more(ok, a little more than a few) questions about that circuit, how many parts go into having a meter? And why only one output for the meters? Is the other side of the meter connected to the output? Whats up with only one output, would the device being connected just be connect to a ground to complete the circuit? I guess what I'm trying to ask is how does it work? Forgive my ignorance, but I just finished learning how my previous design [would have] worked [and why it didn't], but this, this is beyond me...

 

[ronv]

I'll put it together for my own benifit. It gets simpler without current limit, but it's nice to have. You can still use your transformer. Do you know the specs?
Let's see if the circuit gets a critique.

 

[audioguru]

Let's see if the circuit gets a critique.

The schematic should have black lines and text on a white background instead of the blue lines on a dark grey background.

 

[kjennejohn]

Try this power supply:
Variable DC Power Supply - RED - Page36
I googled for a simple variable 24V power supply and found this design on the first page. This does 0.7V to 24V DC, good for 2 Amps, with current limiting. This comes pretty close to what you want. Keep in mind this was designed for 220V mains, but you already have the 110V transformer, so should be good to go. You substitute your bridge rectifier for D1 and D2. Now you have to find the 2N equivalents for the transistors, unless you can find them by their original part numbers.
Later.
kenjj

 

[Hank102938]

Try this power supply:
Variable DC Power Supply - RED - Page36
I googled for a simple variable 24V power supply and found this design on the first page. This does 0.7V to 24V DC, good for 2 Amps, with current limiting. This comes pretty close to what you want. Keep in mind this was designed for 220V mains, but you already have the 110V transformer, so should be good to go. You substitute your bridge rectifier for D1 and D2. Now you have to find the 2N equivalents for the transistors, unless you can find them by their original part numbers.
Later.
kenjj

This looks pretty simple. It has variable voltage and current too? Anyone have a thought on if it would work or not... seems rather simple compaired to ronv's circuit and simple sometimes means non-working.

 

[audioguru]

This looks pretty simple. It has variable voltage and current too? Anyone have a thought on if it would work or not... seems rather simple compaired to ronv's circuit and simple sometimes means non-working.

Because it is extremely simple then its voltage regulation is poor. It doesn't even have a voltage reference and has only a single transistor (Q1) as an error amplifier so its voltage will change with the load current, the input voltage, the temperature and maybe the position of the moon.
Its variable current-limiting has the same problems.

When its output voltage setting is turned up (P2 is turned down) then the voltage regulation becomes worse.

 

[Hank102938]

Because it is extremely simple then its voltage regulation is poor. It doesn't even have a voltage reference and has only a single transistor (Q1) as an error amplifier so its voltage will change with the load current, the input voltage, the temperature and maybe the position of the moon.
Its variable current-limiting has the same problems.

When its output voltage setting is turned up (P2 is turned down) then the voltage regulation becomes worse.

Well I don't want any moon moving to take place, so scrap that design. So, is ronv's desgin my best bet here or are there better ways to get the output I want?