[Spacehead]

remove c3 and c4
 

 

[bidoux]

 
Quote:

Another potential problem with big caps on the output of a virtual ground splitter has to do with stability. Some circuits will become very stable in this situation: no bandwidth and no gain, hence no oscillation. Most circuits aren't made to cope with capacitive loads, however. They become less stable when driving a capacitive load. Study the datasheets for the ICs you will be using. Unless they specifically tout the fact that they can drive large capacitive loads, beware of using them in virtual ground circuits. Don't forget to consider the system bypass caps, if they go from each rail to virtual ground: there are many chips out there that will become unstable with less than a nanofarad of capacitance on their output, and the bypass capacitors will count against this. Ultimately, you will have to build real circuits and test them before you know whether a given chip can cope with the capacitive load in your setup.

I think it is this text we are suppose to quote in this situation. Your op-amp might oscillate with C3 and C4.

 

[tamu]

it was running ok till I shorted the rail to ground by accident and now the chip is burned I think.. I only get distortion. However it was very fun to build and I might try it again with another opamp..

 

[G.Trenchev]

Why are you guys always bothering with these virtual grounds circuits ?
Can't you just use 2 batteries instead of one?

 

[Fred_fred2004]

Have a read
 
http://www.tangentsoft.net/elec/vgrounds.html
 
really explains it well
 
cheers
FRED

 

[pictureguy]

Tamu, couple of Questions.
What opamp in your virtual ground circuit?
If I connect this to the CMOY, do C3/4 replace the PS caps in that circuit?   I have a pair of 470ufd there now.  
What voltage can I feed this?  I have an isolated 24vdc wall wart.  Would that work?
 
Also,  How do you like your DacMagic?  It's a long story, but I'm thinking of taking the minor quality hit by dumping my CA840c player and my upsampling DVD player in favor of an OPPO 83se with DacMagic.  I'd use the 2nd set of 
inputs for an Airport Express.....wireless from my confuser. Balanced outs don't hurt, either.  Problem?  My '840 simply doesn't like the AE and produces some Really Awful sound artifacts because of the horrible jitter in the AE.
Any sugggestions?  

 

[tamu]

I used the cheap as chips ne5532.
the whole circuit replaces the cmoys 2caps and 2resistors psu. so you end up connecting the rails and the ground to the amp circuit.
 
edit: have a look at the link fred posted. great article from tangent
the voltage will depend on the capacitor ratings you have.. if you have 25v rated caps then no problem. if you go below, the caps will open up like flowers
 
I like the dacmagic. I didnt have much experience with others but dacmagic is more than enough for me. Very nice balanced sound. Im sure you will like it too.
I have no idea about the jitter issue sorry

 

[jrm]

So, finally started working on my CMOY last night.  A few things I'm learning:
 
1. I am TERRIBLE at soldering!  I got the power section up and running (surprisingly), but, man, the underside of the board looks pretty sad!
2. I need a better soldering iron tip.  My old iron tip is really oxidized and as such only parts of it will tin up correctly.  I think its time for a new tip... a smaller tip... an easier tip to work with.
3. I shouldn't solder when tired.  I got started on the amplifier circuit and messed up the first two resistors pretty nicely.  Put them in the wrong place and I'm not handy enough with a braid yet so I've got some problem solving to do.
4.By the time I'm done, I should have a nice burn on each of my fingers
5. I have no idea how you guys solder a piece onto the board while a) holding the piece in place (socket) on the underside, b) holding/maneurvering the iron, and c)holding and manuvering the solder.  Even with the helping hands, I'm still about two hands short!
6. This is very fun and hopefully I get better at it.. fast!
 
Thanks for being such an informative community!
 
-jon

 

[bidoux]

Soldering on a perf board is really more difficult than doing it on a proper PCB. And I'm sure you need a good soldering iron.
 
For soldering sockets, well most of the time I burn my fingers, even though I'm holding it through a sheet of paper. And because I only have two hands, I hold the socket and the board at the same time and I bend the solder in a way toput it closer to the pins. I hope someone has a better method !

 

[nikongod]

 
Quote:

Soldering on a perf board is really more difficult than doing it on a proper PCB. And I'm sure you need a good soldering iron.
 
For soldering sockets, well most of the time I burn my fingers, even though I'm holding it through a sheet of paper. And because I only have two hands, I hold the socket and the board at the same time and I bend the solder in a way toput it closer to the pins. I hope someone has a better method !

I agree with your point about perf-board PointToPoint. Its tricky work! 
 
Anyways, to solder a DIP-8 socket here is how I do it.
 
Put socket in board. 
 
Hold socket by 1 row of pins.
 
Solder 1 corner pin on the row you are not holding.
 
Inspect socket for flatness to board. Resolder 1 corner if necessary
 
Solder diagonal corner.
 
Inspect work....
 
Solder all remaining pins.
 
Once you get the hang of it it takes longer to read that than actually do it.
 
For soldering resistors:
 
Bend the resistor leads so they fit through the holes as necessary. 
 
Mount the resistor where you want it.
 
Bend the lead outwards slightly. just a few degrees will usually hold the resistor in place. If you are supremely confident that the resistor is in the right hole and that this will not result in shorting (a possible problem if you have a groundplane....) bend the lead so that it is flush with the board.
 
solder 1 joint. 
 
inspect. 
 
solder other joint. 
 
This works about 90% of the time for me. Although I still rarely make it through a project without soldering myself directly, or holding something I am soldering. The good news is that I have not actually burnt myself doing that in ages

 

[pictureguy]

 I use one of those kitchen scotchbrite / sponge pads with water....to clean my iron tip.
That and some RatShack flux has brought the tip back from the brink.....
As for my soldering skills..... MY EYES ARE SHOT.   period.
Before I get too much further into this, I'm getting a magnifier-on-a-stick and I will build
a board stand to hold while I solder.  

 

[cobaltmute]

Masking tape is also very helpful for holding items to the board while soldering.
 
My latest strategy involves:  tape the part to the board, flip the board over, solder one lead, reach under board board and push up on the part to make sure it is tight while reheating the lead I just soldered, solder the other lead.

 

[chum_2000_uk]

Totally agree with the tape tip. When I made a CMOY I didn't have a set of helping hands or think to use tape. I really struggled with some things, but managed to get it done eventually. My 2nd DIY build was a Jaycar amp, and I found helping hands invaluable, but some things also required taping as described above before putting the board in the helping hands.
 
As also already mentioned, the types of board used for CMOYs are not as easy to solder neatly as PCB's. I've not seen too many CMOYs that look super neat underneath. Mine was a mess, partly due to the difficulty of using the ratshack boards, and partly due to my lack of soldering experience at the time. I took my time with it, visually inspected it and made sure I let the joints cool first before clipping the leads to avoid cracked joints. It worked first time luckily enough. Seriously, take your time and don't work on it if you are tired. Almost fried my Jaycar by wiring it up wrong in the early hours of the morning trying to get it finished. Not to mention electrocuting myself with mains voltage. Wont do that again, and lucky to be here to be giving you guys tips!

 

[jrm]

Yeah, I'm finding that soldering on the radioshack boards is much harder than soldering ona circuit board.  I took a break from my CMOY build yesterday afternoon and soldered together a minty boost (made with a prefab circuit board).  It was MUCH easier.  I'm thinking that if this CMOY DIY doesnt work out, I might give it another try but with a kit and a premade board.
 
Glad the electrocution didnt take you out of the game Chum!

 

[tangent]

Quote:

I'm finding that soldering on the radioshack boards is much harder than soldering ona circuit board.

True, but it's a great way to stretch your skills.  I'd venture to say that until you can make clean joints on crappy RS protoboard, you don't know how to solder properly yet.