Can you help me find some info on an IC?

Discussion in 'Archived Threads 2001-2004' started by Tobey, Mar 19, 2003.

  1. Tobey

    Tobey Auditioning

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    I'm looking for some info on an IC chip. It's the amplifier chip inside my Cambridge speakers. It's a proprietary chip from Creative but I can't find any audio amp IC's that even start with the "CT" prefix. I do know that it is a dual 22 watt and 8 watt IC. I'm thinking about making some mini tri-amped speakers for my pc. I know it's just a toy set of speakers but I'm playing around with stuff I having laying around the house.

    It has these numbers on it,
    Creative
    CT1975-SAM (This is probably the chip number)
    W880E0022

    I need to find any audio IC that starts with CT or CT1975.

    I know it's a lot to ask but I'm all searched out.

    Thanks [​IMG]
     
  2. Isaac C

    Isaac C Stunt Coordinator

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    Consider using other chips. I'd imagine it would be cheaper too since chips like the LM3886 and LM3875 are available as free samples. All you'll need are a few caps and resistors and a ready-made circuit board from, perhaps, The Audio Pages (specifically this project pictured below).

    [​IMG]


    hth [​IMG]

    Isaac
     
  3. Tobey

    Tobey Auditioning

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    Thanks, those kits look nice, but I would like to use the stuff that I have on hand.
     
  4. Dan Dubeau

    Dan Dubeau Auditioning

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    Isaac, i was just wondering if you could tell me how or where i would go to get a LM3875 chip as a free sample.
    I'm interested in building a gainclone using one of these chips. Thanks
     
  5. Isaac C

    Isaac C Stunt Coordinator

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    Tobey, Rod's projects only come with inexpensive circuit boards, nothing else. So you can use the stuff you already have at hand. The Gainclone is another minimalist amp. It's so simple, everything could be wired up point to point.


    Dan, National Semiconductor offers free samples of their products. Down to the middle of the LM3875's page you'll find the blue Samples button. Shipping is free as well (but be reasonable in the amount of samples you request of course).


    Cheers [​IMG]

    Isaac
     
  6. Dan Dubeau

    Dan Dubeau Auditioning

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    is four a reasonable amount or is that too many?
     
  7. Dan Dubeau

    Dan Dubeau Auditioning

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    Nevermind i, read the website, they allow five per week. I'll never need that many i just ordered four.

    Do you think it wil matter what i put in the "company name box" I put "none" but after reading thier site it seems they only cater to companys
     
  8. Tobey

    Tobey Auditioning

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    OK Isaac, It's all your fault! [​IMG]

    I've been looking through the link you posted and I think I'm going to build that amp, but I'm also going to add a third module with the LM3886 in the bridged mode for the sub, which is in a band pass box.

    I'm thinking about these Peerless tweeters, these Viva woofers, in these boxes. I bought the boxes on sale for $14 for a project like this. I have a 21' inch monitor and they should look nice sitting next to it. [​IMG]

    I figure it should sound good using the LM3886 in the bridge mode, it puts out 100 watts and using two LM3876's for the tweeter and mid-woofer. I'll probably also use his cross-over too.

    I'm selling my Ducati so I need a new hobby, and I used to repair consumer electronics for years. This little "toy" should sound real nice for a set of computer speakers.

    Thanks,
    Tobey [​IMG]
     
  9. Isaac C

    Isaac C Stunt Coordinator

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    Dan, you could put student (which is what I put), hobbyist or DIYer in the Company edit box, that's fine.

    Tobey, I bet that'll make a nice pair of multimedia speakers -- better than stock plastic computer speakers. Those Peerless tweeters aren't shielded, are they? Here's an 8-ch amp based on Rod's P19 [​IMG] Be warned, this hobby is addictive [​IMG]


    Good luck!

    Isaac
     
  10. Tobey

    Tobey Auditioning

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    Isaac, thanks very much for your input. I didn't realize how common of a chip the LM3876 is untill you mentioned it. I've built tons of small projects in the past, but it has been a long time since I've built anything.

    Even though it's not as good as many things I've seen posted here, here's the most technical thing that I've designed and built. When I was repairing electronics I worked on a lot of high-end car amps such as Rockford Fosgate, Orion and Autotek. I needed a DC power supply to run them at or near full output. I found a surplus transformer and built a variable power supply around it. I contacted the manufacturer of the transformer, got the specs and went from there.

    It's regulated from 1.2 to 24 volts DC, full wave rectified, with a current output around 75 amps. Also has very little ripple voltage. This thing is a beast, you can damn near weld with it and at full power out it will dim the lights in the room. It definitely needs a good AC source. The fan turns on and off automatically at a certain temp, and with the remote control box I can set the supply under my desk.

    Top

    [​IMG]

    Front,

    [​IMG]

    Rear, At the left of the heatsink is the diodes, next in the sockets is the regulators (with the resistors) then eight power transistors for the output.

    [​IMG]

    Remote control box,

    [​IMG]


    Thanks again, you've help spark a hobby I haven't "played with" in years. I built that supply around 1988 and haven't really built anything major since. When I get my amp built I'll be sure to show you. [​IMG]
     

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