[rds]

Quote:

Originally Posted by tourtelot /img/forum/go_quote.gif So perhaps I had the 100ohm load resister wired in correctly.

This is why Tangent asked for hi res pictures. I'm pretty sure he doesn't mean the maximum resolution your camera can produce. Something like 1024x768 should be plenty.

When it comes to troubleshooting circuits a good picture is often worth much more than a thousand words.

 

[tourtelot]

Maybe Tangent would be so kind and chime in here. Would it be better to try and send pictures of the build close-up, or do you want to see a larger version of the rig in "test mode?" This would show the 100ohm resister?

As to pictures, unless I am missing something, the amount of space allowed by the forum for .jpg pix is very small. I'll try and PS them to LESS rez so that the sent image can be bigger than 1x1 and still fall under the limit.

D.

 

[tourtelot]

Just spent some time with an EE friend who helped me diagnose my problem. It seems that my 18VAC power supply is not enough to keep the regulator from coming out of regulation under the 100ohm (worst case) load. I am going to spend a little while figuring out a larger C5 that will work with this supply, 'cause it's all a learning experience.

God help us all when I start on the PPA. Could be a bumpy flight<g>.

D.

 

[grenert]

Quote:

Originally Posted by tourtelot /img/forum/go_quote.gif Just spent some time with an EE friend who helped me diagnose my problem. It seems that my 18VAC power supply is not enough to keep the regulator from coming out of regulation under the 100ohm (worst case) load.

That isn't really that tough a load. According to your entries into the Tangent Estimator, the transformer was rated at 1A. You aren't anywhere near that.

You could test the theory by halving the load by putting the other 100 ohm resistor in series (I know those Radio Shack resistors come in pairs) to make the load 200 ohms.

 

[tourtelot]

No, it is not a tough load, but well above what the PPA draws. The 100ohm load makes the regulator drop out of regulation. The TREAD may or may not misbehave with half that load but it seems that I should either up-volt my wall wart or increase the size of C5 and make it right to the regulator. I really believe that my choice of an 18VAC transformer was too "skinny" to work correctly.

I will try the 200ohm load it just to see.

D.

 

[tourtelot]

And, FWIW, with a 200ohm load, the TREAD seems much better. Output (TP2 to TP3) is 23VDC and .54mVAC. Post bridge but pre regulator is 25.5VDC and 410mVDC. PPA draws less than .125A.

D.

 

[grenert]

Quote:

Originally Posted by tourtelot /img/forum/go_quote.gif And, FWIW, with a 200ohm load, the TREAD seems much better. Output (TP2 to TP3) is 23VDC and .54mVAC. Post bridge but pre regulator is 25.5VDC and 410mVDC. PPA draws less than .125A.

Man, I don't even know how you're measuring that, given the varying methodology you've tried. You seem awfully sure you've got things figured out, while at the same time you've never even provided the specs on the transformer you're using.

And a TREAD is easy compared to the PPA...

 

[rds]

If you're going to make a PPA the first thing you NEED to figure out is how to upload some pictures and post them in this thread, kinda like this:

Until that happens this discussion is just a waste of time. We need to see what you've built and how you're measuring it.
It would also be good to take a picture of your multimeter connected to your circuit with the measurements on screen. Then we can see what you're measuring and what your multimeter settings are.

 

[tourtelot]

Nope, not sure at all. Just trying to figure it out.

BTW, the mixed methodology comes in part from the various advice that I have gotten here from a number of different folks, mostly laced with "why, even a dummy knows this," all of which may be good advise but hard to listen to it and pay attention.

I'm just sayin' Pretty haughty bunch overall. I am a multi-thousand poster on my professional newsgroup and I try and always treat the newcomers with the axiom, "There are no stupid questions. Just ones that you haven't learned the answer to."

So I don't think that this project or any other is worth me having to hear attitude from a bunch of kids. I have one of those that I HAVE to listen to. She's my daughter.

I think my friend at Mackie and I can have a much more fun working out the kinks in my educational shortcomings than I have had with all of you.

Have a great time showing each other what great iPod harnesses you can make. Peace out!

D.

 

[DKJones96]

I use a non-regulated wall wart rated at 9v putting down 12v from the lack of load... You guys make this too hard for yourselves!