Guide to fix up a Cmoy 2

[Natsuiro 0]

I will use just a laptop built in sound card to watch movies and maybe test on a pcdp but mostly just the laptop. Is there a way to change resistor values to increase battery life or a way to power the amp via usb power?

[jasonhanjk 0]

Yes, you need to take care of the polarity. You measure which side have higher potential then you put in the cap. If the source already have output cap, you can jumper it.

[jasonhanjk 0]

You can build a power supply that I just posted in this forum but you are not able to use the USB power. Unless you use chip like LM4477 which are low powered one.

 

80mW USB powered amp will be my new design.

[Username 0]

Jason: getting confuse here, you said that CMOY2 was based on A47 and that a47 gets about 4hr on a 9v battery. However I am getting much more than 4hrs, did you modify anything?

[jasonhanjk 0]

The A47 have 47 ohm resistor at the output, that resistor will actually act as a load and use up power when you listen to music.

Cmoy 2 removes that resistor but there is always a price to pay. It increase the possibility of oscillation. I try out with my EW9 and it gives around 6 hours. Will try again tonight.

[jtfoo 0]

Jason, if using electrolytic as input cap, does the polarity matter? In other words, does it matter which way you place the cap? I have used Oscons as input caps and they don't sound so bad.

For line level input, it should be alright since the voltages are so low. However, to be safe you can convert your elco cap to bipolar by connecting two similar caps in series. Connect them as such,

+  - -  +
|C1|--|C2|

   or
-  +  +   -
|C1|--|C2|

 

Take note your cap value is halved. e.g if connect two 10uF in series, the resultant value is 5uF.

 

 

[jasonhanjk 0]

Thanks jtfoo.

 

Or better still, you can get non-polarized elec cap. Don't know where got sell though...

[jtfoo 0]

Thanks jtfoo.

 

Or better still, you can get non-polarized elec cap. Don't know where got sell though...

Larry Hifi got BlackGate bipolar cap, but very expensive. Koba also have cheaper brands.

[Username 0]

Cmoy 2 removes that resistor but there is always a price to pay.

 

There are two 47ohm resistor at the end. are you referring to the one after IC1 or IC2?

[Fresno bob 0]

Is there anyway to order one these pcbs with out using paypal or can the eagle layout be posted to print the pcb's ourselfs.

 

Also is this pcb for use with the alps-RK0971221Z05 pot

Edited April 20, 2005 by Fresno bob

[Guest starushz]

Hi guys i got the cmoy2 pcb. Anywa im asking what typd of audio jack you all use?

As in any special one or those normal from SLT $1/piece one?

 

[Fresno bob 0]

Since these boards can not be brought with out the use of paypal i guess i will have to try to make my own.

[kahchun 0]

Can someone teach me how to fix up a on/off switch?? I bought one that is have 6 legs.

 

jasonhanik, can you post up the full schematic?? This is because the first amp I make, i actually damage the soldering point of the output side, thus, I'm now using wires to jump directly to the nearest component at the route of the individual channel. However, I couldn't get my right channel to work, do i connect directly to resistor R6?? I did this at first, there was sound at the right side initially but it got cut off and after that can no longer get the right side up again? Any idea what went wrong? Tested the opamps are still working properly.

 

So sorry for the long questions, this is my first project.

[Username 0]

Kachun:

 

ACtually a three legged switch (in fact a 2-legged would be perfect) is enough for this application. However I think it is still workable with what you have.

 

 

To +ve terminal of batt

|

| To +ve on the PCB

| |

. . .

. . .

 

It looks something like this? just connect your two points to either the topmost left two, topmost right two, bottom left two or bottom right two. The example I bolded is topmost left two. Flick the switch abit and use multimeter to measure, there should be very very very little ot no resistance if the circuit is close.

Edited April 26, 2005 by Username

[kahchun 0]

Kachun:

 

ACtually a three legged switch (in fact a 2-legged would be perfect) is enough for this application. However I think it is still workable with what you have.

 

 

To +ve terminal of batt

|

| To +ve on the PCB

| |

. . .

. . .

 

It looks something like this? just connect your two points to either the topmost left two, topmost right two, bottom left two or bottom right two. The example I bolded is topmost left two. Flick the switch abit and use multimeter to measure, there should be very very very little ot no resistance if the circuit is close.

Thanks for the help. Will try it tonight. So, the negative of the batt just go straight to the negative of the board right? As for the positive I just connect to either of the combination you have stated right?