[omegamajor]

Quote:

Originally Posted by manaox2 Anything over 25V is dangerous from what I know (not testing that myself), 48V can possibly be lethal. You would feel it if a cap on this project were to discharge into you...

It's the current you need to worry about, not the voltage. About 100mA or less directly through your heart will stop it. Around 10mA will start twitching muscles. A static discharge from shuffling your feet and touching a doorknob is thousands of volts, just a tiny amount of current. Human skin provides a high amount of resistance, on the order of megaohms. If you have a cut on your finger and get a static shock through it the shock feels much more substantial than if you didn't have a cut. If you touch 120VAC power you will feel a little buzz, but it won't harm you (unless you have the aforementioned cut on your skin). I've personally touched a cap that was charged to 400V (on accident of course) and received a little bit of a shock, but mostly it was just a strong tingling sensation.

Don't worry about the caps in the SS. They will discharge themselves since they are already in the circuit.

 

[greeny]

Hi guys,

Where else can i find the tubes?
It seems that they dont have it in my country singapore.

 

[mattcalf]

Quote:

Originally Posted by habba /img/forum/go_quote.gif Hi guys, Where else can i find the tubes? It seems that they dont have it in my country singapore.

Unfortunatelyit seems the 19J6 tubes are out almost everywhere.

There are a few that go on eBay but they are mostly overpriced.
You might want to google search radio tube suppliers and email around to get a pair.


Good luck!
Matt.

 

[greeny]

Ahh i think i found them, haha shipping cost more then the tubes!

 

[jeanba3000]

Hello

I've been informed that tomorrow, The Tube Center will have a small stock of 19J6 tubes ! $4 each.

I already have ordered my tubes

 

[Yaka]

Quote:

Originally Posted by manaox2 /img/forum/go_quote.gif Anything over 25V is dangerous from what I know (not testing that myself), 48V can possibly be lethal. You would feel it if a cap on this project were to discharge into you as I believe they are all seeing the full voltage at points. You can make a discharge circuit easily though, I need to make one myself. http://www.repairfaq.org/sam/captest.htm#ctdtk

Quote:

It's the current you need to worry about, not the voltage. About 100mA or less directly through your heart will stop it. Around 10mA will start twitching muscles. A static discharge from shuffling your feet and touching a doorknob is thousands of volts, just a tiny amount of current. Human skin provides a high amount of resistance, on the order of megaohms. If you have a cut on your finger and get a static shock through it the shock feels much more substantial than if you didn't have a cut. If you touch 120VAC power you will feel a little buzz, but it won't harm you (unless you have the aforementioned cut on your skin). I've personally touched a cap that was charged to 400V (on accident of course) and received a little bit of a shock, but mostly it was just a strong tingling sensation. Don't worry about the caps in the SS. They will discharge themselves since they are already in the circuit.

confused, but just to be sure would using a screw driver to discharge be ok? as i dont think i have enough parts to build a tool to discharge

 

[Fitz]

Quote:

Originally Posted by Yaka /img/forum/go_quote.gif confused, but just to be sure would using a screw driver to discharge be ok? as i dont think i have enough parts to build a tool to discharge

Tool to discharge = resistor taped to a stick. Not too terribly expensive.

 

[pistolsnipe]

Quote:

Originally Posted by jeanba3000 /img/forum/go_quote.gif Hello I've been informed that tomorrow, The Tube Center will have a small stock of 19J6 tubes ! $4 each. I already have ordered my tubes

thanks for the heads up, just ordered 4, he said they had ~ 50 and is only selling a few to each person to make sure as many people can get them.

 

[tomb]

Quote:

Originally Posted by pistolsnipe /img/forum/go_quote.gif thanks for the heads up, just ordered 4, he said they had ~ 50 and is only selling a few to each person to make sure as many people can get them.

I just spoke with Stan at ESRC (The Tube Center, Orlando Tubes, etc. - all the same guy). He says 47 at the moment and is expecting to sell all of them by the end of the weekend.

So, anyone that wants them - get busy!

 

[sebrkln]

I really hope someone can help me out here, because I've completely exhausted my troubleshooting capabilities. I'm following the schematic correctly as far as I can tell. So here's what I'm getting.

1) The heatsinks warm up within a minute of turning on the amp, so I at least know the MOSFETs are getting power, right? The tubes however both remain cold (and dark).

2) I get a quiet thumping from headphones when the amp is turned on, nothing else (as I would expect considering the tubes)

3) My power supply reads a steady 48V when not plugged into the circuit. When plugged in, the readings are all over the place. Both tubes oscillate from 5.75 or so to 8V, read from the spots labeled 1 and 2 on the diagram. Right before C1, the meter reads from 4 to about 18V.

Anyone have any ideas as to where I should go from here? They would be much appreciated!

K

 

[-=Germania=-]

You might have wired the tubes in reverse. Check that pins 1-7 read from the correct direction.

 

[CaptHowie]

1. Are the PCB's any closer to being produced.
2. A step-by-step tutorial?

I've built a CMOY already but I used Tangent's excellent tutorial and im scared that I wont be able to read the schematic and stuff it up completely.

 

[CaptHowie]

Ok, forget my previous post... [DISAPPEAR] except for the question on the PCB's... I still want to know when they'll be done!

I've had a good look over the schematic and it is actually very simple

I have still got a few questions though

1. With the ground connections, where can I connect them to? In the other amps shown here they used a blank PCB etchboard, and if that is what I have to use, is it a simple matter of hot gluing it to the bottom of the case and soldering ground connections straight to it, or is it a bit harder?
2. With the connection markings (the black dot connecting wires), there are a few on the same wires (most...). Again, is it a simple case of stripping part of the wire and soldering connections to it, or a bit more?
3. I know somewhere in this thread there was the tube pinouts, but the head-fi servers were taking a beating and the search wasnt working

So what are the pinouts?

Thanks in advance.

 

[iareConfusE]

I too am looking forward to the PCB's soon.

 

[ltmon]

Quote:

Originally Posted by CaptHowie /img/forum/go_quote.gif 1. With the ground connections, where can I connect them to? In the other amps shown here they used a blank PCB etchboard, and if that is what I have to use, is it a simple matter of hot gluing it to the bottom of the case and soldering ground connections straight to it, or is it a bit harder?

If you use a conductive (i.e. metal) chassis, connect your ground to it. If not, use the blank etchboard. It doesn't need to be connected to anything, it should just unify all the grounds in the circuit together to a single electrical point.

Quote:

2. With the connection markings (the black dot connecting wires), there are a few on the same wires (most...). Again, is it a simple case of stripping part of the wire and soldering connections to it, or a bit more?

Close enough. Most people will use some heat shrink tubing in various places to prevent exposed wires shorting on other components etc.

Quote:

3. I know somewhere in this thread there was the tube pinouts, but the head-fi servers were taking a beating and the search wasnt working So what are the pinouts?

The tube sockets will have the numbers 1 to 7 marked on them, matching to those numbers on the diagram.