gainclone from rat shack parts...

[nerd of nerds]

hello, i ve been interested in building a gainclone for quite some time now and just now got my "samples" from national semiconductor...i have 5 lm3875t chips and don't want to screw around with "exotic" components since this will be my first amp and i want to save some money on it...soooooo...i have been checking and it looks like radio shack should have everything that i need to build a gainclone but i don't know about transformers...i have never worked with them before and i need some info...information on the raido shack site is pretty scarce when it comes to their transformers...

will the transformers that radio shack has work for this?

if so which one should i get?

THANKS!

[mateo88]

I believe Radio Shack has a 24v center tapped transformer that puts out 5 amps. That would work nicely, but it might clip a little sooner than you would like. It can work, though. You won't be dissapointed with the sound quality, I can assure you. If you find the bass of the lm3875 a little soft or not punchy enough, try an lm3886. The only extra part you need for that is a mute resistor. Good luck, and happy building!

[garbage]

hi

not sure if 4x 12v Sealed Lead Acid battries are actually cheaper than transformers in US, but this is worth checking out if you want to build GC on the cheap. (one 12v SLA ranges from 10 - 12 odd USD here)

for charging circuit of the SLAs, you can use this : charger from vt52.com

cheers
garbage

[nerd of nerds]

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CT LG%5F011%5F002%5F016%5F000&product%5Fid=273%2D1512

if so, cool!

[mrlots2do]

I did a search on Ratshack's site. Several transformers but not enough info posted. Visit a store, ask for models with 2 secondaries of 18-25v. Next problem is va rating, GC's need about 100va each.

[Sherman]

Originally posted by nerd of nerds
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CT LG%5F011%5F002%5F016%5F000&product%5Fid=273%2D1512

if so, cool!

You really need at least 18V for a GC. The RS transformer is a 24VCT meaning it gives 2 x 12V, not enough if you use the CT. If you can find a larger transformer you do not have to have dual secondaries to have a dual bridge PS. I've built several GC PS with dual bridges using CT transformers.

If you want to use the RS transformer you can use 2 of these to create a dual bridge PS or just one to create a single bridge PS. As I said the problem isn't lack of dual secondaries, but lack of voltage.

[KCHANG]

I've used the 25.2VAC CT 2A Radio Shack transformer in the power supply for powering my various Gainclones. It works just fine.

"You really need at least 18V for a GC. The RS transformer is a 24VCT meaning it gives 2 x 12V, not enough if you use the CT."

Depending on whether you are talking about AC or DC. The 2x12.6VAC will give a bit more than +-17VDC after the rectifier.

Ciao,

Kurt

[soundNERD]

I thought u want to save money? What are you doing at RadioShack???

I'd say get your parts from a Fry's Electronics if you have one nearby. If not, you would be better off ordering them from a distributer for 10 cents a piece and paying 6 bucks to have it shipped.

Dont even think about powering an amp with a 2A transformer, especially only a 12-0-12 one. That would get like 10W peak output.

[woody]

Check out the listings at Apexjr.com in paticular he has a cute
little ~100 va 44v ct toroid for about $13 if you don`t push
the amp real hard this might work for a single channel. He also
has a lot of surplus caps.


Woody

[soundNERD]

Even if you do push it, +/-30V or so is nothing to a 3875