Do we yet have a circuit diagram of exactly what the OP has done? Without this we are all fumbling in the dark.
Post #9
Unregulated supply with a 47uf reservoir cap and possible wiring problem of centre tap if it happenes to connect to the zero volt line.
Hi Audio peoples.
OK, I am still waiting on the correct cap but I did with two 480uf's in series to get close.
Also I have some more pictures for you guys.
Here is the PS in the case.
Here is my breadboarded rectifer. Looks ugly but i'll dress it up when it goes in the case.
And here are the readings on it. The ripple doesn't occur until I put a lamp or some other kind of load on it.
So it looks like even with the larger cap I am still getting ripple. I have yet to modify the rectifier section with a regulator but will probably be doing that when I have some time this evening. I know that some ripple is probably unavoidable but any time I connect an audio circuit to this I can hear the heavy modulation.
OK, I am still waiting on the correct cap but I did with two 480uf's in series to get close.
Also I have some more pictures for you guys.
Here is the PS in the case.
An externally hosted image should be here but it was not working when we last tested it.
Here is my breadboarded rectifer. Looks ugly but i'll dress it up when it goes in the case.
An externally hosted image should be here but it was not working when we last tested it.
And here are the readings on it. The ripple doesn't occur until I put a lamp or some other kind of load on it.
An externally hosted image should be here but it was not working when we last tested it.
So it looks like even with the larger cap I am still getting ripple. I have yet to modify the rectifier section with a regulator but will probably be doing that when I have some time this evening. I know that some ripple is probably unavoidable but any time I connect an audio circuit to this I can hear the heavy modulation.
Assuming this has to drive the valve heater as well as the 'HT', a 47uF is almost no smoothing at all. Two 480's (470's?) in series is 240uF, which will give you about 7V ripple. To get below 1V pk-pk ripple you need 1500uF. The regulator can then clean this up.
Find out how to do a ripple calculation. It involves calculating the charge removed fromthe cap for each mains half-cycle, then dividing by the capacitance.
Find out how to do a ripple calculation. It involves calculating the charge removed fromthe cap for each mains half-cycle, then dividing by the capacitance.
Thanks DF96. I plugged in three 480 uf in parallel and the ripple was greatly reduced but now has movement to it.
Also, my scope will not see it under DC at this point only under AC. Anyone suggestions as to why this is.
I am relatively new to electronics and extremely new to scope operation.
Also, my scope will not see it under DC at this point only under AC. Anyone suggestions as to why this is.
I am relatively new to electronics and extremely new to scope operation.
Thanks DF96. I plugged in three 480 uf in parallel and the ripple was greatly reduced but now has movement to it.
Also, my scope will not see it under DC at this point only under AC. Anyone suggestions as to why this is.
I am relatively new to electronics and extremely new to scope operation.
The only way you will kill all the ripple is either with a regulator (although we're not sure there is enough "headroom" to work with for that) or an active ripple filter.
The scope is essentially just a voltmeter, always remember that. So the reason you can't see the ripple on the DC is because the DC voltage drives the trace off the screen. When you AC couple the scope you are left with just the AC component riding on that DC voltage which makes it possible to see and measure easily.
I still think an analogue scope takes some beating and would take one any day over a digital. Bandwidth is everything, the one I use is a 100Mhz dual trace which is great for audio.
http://www.diyaudio.com/forums/head...le-ended-class-headphone-amp.html#post2075959
http://www.diyaudio.com/forums/head...le-ended-class-headphone-amp.html#post2075959
Like this one,
Hung Chang 5510 Oscilloscope 100 MHz 3 Channel | eBay
They call it a three channel here... it is really in all fairness and it can actually display up to 8 traces if you put a bit of spin on the description.
Hung Chang 5510 Oscilloscope 100 MHz 3 Channel | eBay
They call it a three channel here... it is really in all fairness and it can actually display up to 8 traces if you put a bit of spin on the description.
That would certainly be nice. Wife and I have a kid on the way so no new toys until we find out what kind of $$ we are talking about with the kid.
Back to the PSU.
After adding 2200uf of smoothing everything looks much nicer.
Thanks folks for all of your help. I'm on to the speaker forums for help with my next dilemma.
Back to the PSU.
After adding 2200uf of smoothing everything looks much nicer.
Thanks folks for all of your help. I'm on to the speaker forums for help with my next dilemma.
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