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My Fancy Pants Cmoy Build

post #1 of 11
5/19/11 at 3:12am
Thread Starter 

I'm planning on putting together a rather premium CMOY style AMP and trying to figure everything out, I figured I might as well post here and see if someone might help me with some of the planning.

 

What I have planned so far:

  • Auto Shut Off Timer
  • Burr Brown OPA627BP with IC Socket soldered onto the board to protect the Op Amp(and incase I might want to switch later)
  • 2x 9v Batteries
  • The rest is standard CMOY build from http://tangentsoft.net/audio/cmoy-tutorial/parts.html to be ordered from Mouser (Along with battery holder)
  • Custom made case from shapeways

 

I already purchased the batteries, Op Amp and IC Sockets(lol 60 for $4.20) as these weren't being purchased from Mouser, I have about $40 left in my budget.

 

The only thing I'm not sure how to setup is the shut off timer, anyone have any ideas?

 

Other thoughts would be welcome as well.

 

Edit: Updated for current plans.


Edited by zoneykid - 5/19/11 at 8:34pm
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post #2 of 11
5/19/11 at 4:50am

I'll much enjoy seeing that actually working... First - you'll need to filter the USB power in some elegant way (say CLCLCC) and you'll lose 0.5V doing that. Second - have fun driving a Cmoy with 4.5V or... 2.4V on batteries as you intend.

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post #3 of 11
5/19/11 at 5:29am

I don't think you have researched this very well before buying parts...

The OPA627 will not work at the low voltage you have. The slide

on/slide off switch and shut down time will require some sort of

MCU or power management chip. Are you good at programing?

 

Just some things to think of...

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post #4 of 11
5/19/11 at 4:54pm
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

I don't think you have researched this very well before buying parts...

The OPA627 will not work at the low voltage you have. The slide

on/slide off switch and shut down time will require some sort of

MCU or power management chip. Are you good at programing?

 

Just some things to think of...


 

Aye, I didn't do too much research into the Op Amp, A friend of mine told me to get it and when I was talking about using 2 batteries he didn't say anything so I thought it was fine.

 

Its voltage is from 4.5-18 so I should be fine using 3 or 4 AA batteries, the case will just be a little bigger. (I choose not to use 9v due to having already ordered the AA batteries and charger)

 

While I don't exactly know much about programming chips, I'm sure I could learn easily enough, anyone know what kind of power management chip I should get?

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post #5 of 11
5/19/11 at 5:18pm

 

OPA627 needs a minimum of ±4.5V, which means both +4.5V and -4.5V together. So you'll need a bit over 9V total from the batteries, which will then be split into separate + and - voltages.

 
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post #6 of 11
5/19/11 at 5:37pm

Is this your first diy project? If so, you are way more daring than I was.  I'm still trying to get everything looking clean on a cmoy build before I look at modifying it.  Good luck.

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post #7 of 11
5/19/11 at 5:40pm

OPA627 on low voltage is a waste of money. It truly needs at least a 18V supply (+/- 9V) to be worth its price. With 9V (+/-4.5V), the voltage swing will also be extremely limited, as the opa627 can only swing up to about 3V from a 9V supply.

 

I'd consider using two 9V batteries.

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post #8 of 11
5/19/11 at 7:19pm
Thread Starter 

Edit: If you read what was here earlier, forget it. >.>

 

Yeah, looks like I'm gonna use 2x 9v, shouldn't have bought those eneloops. :<

Oh well, I'll find another use for them.

 


 

Quote:
Originally Posted by ClemBurmingham View Post

Is this your first diy project? If so, you are way more daring than I was.  I'm still trying to get everything looking clean on a cmoy build before I look at modifying it.  Good luck.



I've done a bit of audio cable work, but aside from that not much else.


Edited by zoneykid - 5/19/11 at 8:07pm
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post #9 of 11
5/21/11 at 2:08pm

you might be able to get away with using an ne555 timer into a transistor, just set your pulse for fairly long.  this is just a quick off the top of my head idea though, might be more complicated than necessary.

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post #10 of 11
5/21/11 at 3:31pm
Thread Starter 
Quote:
Originally Posted by samsquanch View Post

you might be able to get away with using an ne555 timer into a transistor, just set your pulse for fairly long.  this is just a quick off the top of my head idea though, might be more complicated than necessary.


 

Seems good enough, but is the sensor low power enough to detect an audio signal? I'm thinking of putting it right at the input.

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post #11 of 11
5/24/11 at 12:01pm

Just my 2 cents, I don't think CMOY's are really that great.

 

They are definitely very simple and cheap to build.. but I don't see the point in building a "high performance" one.

It seems to me that it'd make more sense to simply build a better design.

 

 

Don't get me wrong. I recommend building one. But.. I'd would use much cheaper materials and worry more about getting it working perfectly than about the sound.

 

 

 

Also, where did you get the opamp? You are aware that there are tons of fakes of these, and that you should only buying these from a trusted source.

 

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