[bhjazz]

The Pimeta obviously has a nice place for the user to insert a switch. I have also realzied that adding a switch to hot power inlet prior to the Tread would be just as decent.

Seems to me that cutting power prior to the Tread would prevent it's main cap from keeping any charge on it, even though I know the Tread does little without a load to act on. On the other hand, having the whole power inlet and supply in one tidy corner of the case seems nice. I think I ate too much today because I can't think straight.

Any reason why either one would be better? Am I splittin hairs here?

 

[MASantos]

If you want to have just one switch in your setup, then place it before the tread. That way when you switch off, everything will be disconnected. I think this is a safer approach.

 

[bhjazz]

OK. That's what I was thinking as well. I've jumpered the switch connections on the Pimeta, so I'll be good to go.

Thanks!

 

[mono]

I vaguely recall that some opamps may lock up if the voltage doesn't rise fast enough, in which case you speed that up by having the tread transformer field and cap charged, leaving only amp local capacitance as a cause for inrush current.

Further, when voltage drops you might find an instable region where there's a pop, and reducing connected capacitance will tend to decrease the time in that instable zone.

If you prefer to switch off the whole supply, go ahead and do it. Just keep the above in mind if you find that is a problem.

 

[luvdunhill]

bhjazz:

I'm wrestling with the same question you are. I'd suggest reading Tangent's thoughts on the matter here:

http://tangentsoft.net/elec/teps/system.html

 

[bhjazz]

Good stuf here. I'm happy to see that most of us reason through it the same way. luvdunhill - thanks for the link. I had not worked through Tangent's site, and it is obviously a good bunch of info there. (I gotta remember to do that more.)

mono - strangely enough, after running my Pimeta for a few days I am finding that there is a pop at turnoff. So it looks like I will need to pull a few things apart and get the switch into the Pimeta circuit, which will leave the power supply running any time it is connected. I just really don't like the pop coming through my headphones. That can't be good in the long run! Anyway, you nailed it!

Thanks, you two!

 

[mono]

Quote:

Originally Posted by bhjazz /img/forum/go_quote.gif mono - strangely enough, after running my Pimeta for a few days I am finding that there is a pop at turnoff. So it looks like I will need to pull a few things apart and get the switch into the Pimeta circuit, which will leave the power supply running any time it is connected. I just really don't like the pop coming through my headphones. That can't be good in the long run! Anyway, you nailed it!

I have a general purpose 24V supply on my desk that I run my Pimeta (among other things) from, it usually stays turned on. My Pimeta still pops some, it has typical large amount of capacitors/capacitance, if I ever get motivated enough to attempt to fix that I'd considered adding a drain resistor between V+ & V-.

 

[bhjazz]

Ah - so I could possibly leave that idea alone, then... I'll look further into this, though. There has to be a way to keep it from getting all the way to the output (like your drain resistor).

Could a capacitor be used similarly somewhere?

 

[mono]

When I wrote drain resistor I was actually thinking of a bit more, using a SPDT switch with amp V+ rail as common (center) and supply V+ rail as throw 1, amp V- rail as throw two. That way the drain resistor isn't a constant load and a smaller, lower ohm resistor would be used as the off drain.