Uvodee,
Perhaps saying the bulb was not lighted up was slightly inaccurate. With the working rectifiers, when i turned the switch on, there was a very brief(and very low) glow from the bulb for less than a split second, then the (little) light went away. Other than that, there was no obvious light(looked like it was off). The circuit was fine though and everything checked out, except for the wierd DC measurement of course
Perhaps saying the bulb was not lighted up was slightly inaccurate. With the working rectifiers, when i turned the switch on, there was a very brief(and very low) glow from the bulb for less than a split second, then the (little) light went away. Other than that, there was no obvious light(looked like it was off). The circuit was fine though and everything checked out, except for the wierd DC measurement of course
Blackreplica,
I'm glad you are getting better results now. Runebivrin is right - until you have atleast part of the amp circuit conected to the psu you will get inaccurate DC readings, but don't worry about it.
You will definitely need the decoupling caps (1000uF each?) on the power supply rails.
The input capacitor should be used to protect your speakers from DC coming from your source, unless you are sure that your source (CD player, whatever) is not producing any DC offset at all. Reports are that removing it can improve sound quality but only if you are sure it is safe to do so. A good quality film or electrolytic (a Black Gate N type if you can afford it
) is recommended.
The caps across the diodes are there, as you say, to filter any noise in this case coming from the switching on/off of the diodes. I don't use them in my power supply but you can see them implemented on the Basic GC page of Decibel Dungeon.
Let us know how you get on....
I'm glad you are getting better results now. Runebivrin is right - until you have atleast part of the amp circuit conected to the psu you will get inaccurate DC readings, but don't worry about it.
You will definitely need the decoupling caps (1000uF each?) on the power supply rails.
The input capacitor should be used to protect your speakers from DC coming from your source, unless you are sure that your source (CD player, whatever) is not producing any DC offset at all. Reports are that removing it can improve sound quality but only if you are sure it is safe to do so. A good quality film or electrolytic (a Black Gate N type if you can afford it
) is recommended.The caps across the diodes are there, as you say, to filter any noise in this case coming from the switching on/off of the diodes. I don't use them in my power supply but you can see them implemented on the Basic GC page of Decibel Dungeon.
Let us know how you get on....
hehe, just to clarify,
there will be caps on the power supply(that is, the decoupling capacitors on the rails). I'm leaving the other caps mentioned out though(i already have all the parts here for the amp). Yup i choose 1000ufd for the decoupling cap values(i recalled seeing it in someone's schematic on this forum hence the choice).
So now i'm gonna start to build it! Wish me luck!
there will be caps on the power supply(that is, the decoupling capacitors on the rails). I'm leaving the other caps mentioned out though(i already have all the parts here for the amp). Yup i choose 1000ufd for the decoupling cap values(i recalled seeing it in someone's schematic on this forum hence the choice).
So now i'm gonna start to build it! Wish me luck!
Torrid Torroid times
Actually my torroid is 500VA, 2X 25V, 220V Nuvotem Talema one. The circuit was for Peter Danial's circuit, the rectifier bridge used MUR860. Did checked the circuit a few times and seemed to be dandy, plugged into the powerline and the smoothing caps (polarised BG 4.7uF) fried. Is my VA rating way too high? I am really lost friend. Please help....
Actually my torroid is 500VA, 2X 25V, 220V Nuvotem Talema one. The circuit was for Peter Danial's circuit, the rectifier bridge used MUR860. Did checked the circuit a few times and seemed to be dandy, plugged into the powerline and the smoothing caps (polarised BG 4.7uF) fried. Is my VA rating way too high? I am really lost friend. Please help....
To UVODEE: transformer current rating
Hi Uvodee,
I read that you use +/- 18 volts/5 amps transformer for your gainclone amp. Is it in a single supply for both channel? Or you have dual mono configuration?
I ask this because, I plan to use the same voltage transformer. But if I use 5 amps one for single supply, I don't think that it can enough supply two channels (which both totally can easily peak between 8 to 10 Amps).
Thanks,
---
David
Hi Uvodee,
I read that you use +/- 18 volts/5 amps transformer for your gainclone amp. Is it in a single supply for both channel? Or you have dual mono configuration?
I ask this because, I plan to use the same voltage transformer. But if I use 5 amps one for single supply, I don't think that it can enough supply two channels (which both totally can easily peak between 8 to 10 Amps).
Thanks,
---
David
Bridges Mis-labeled!!!
This is a little late in this thread but here it is for what it is worth. I had exactly the same problem with exactly the same bridges from PE. I decided to check them out further this afternoon and discovered that they are
labeled wrong .
The pin labeled AC on both my samples is actually the DC+ and the pin labeled + is actually AC. Connecting AC to the terminal labeled + and the one diagonally from it resulted in a perfectly working bridge. Testing the other one revealed exactly the same situation!
Sherman
-----------------------
Don't touch that! Its hot!
runebivrin said:
This is a little late in this thread but here it is for what it is worth. I had exactly the same problem with exactly the same bridges from PE. I decided to check them out further this afternoon and discovered that they are
labeled wrong .
The pin labeled AC on both my samples is actually the DC+ and the pin labeled + is actually AC. Connecting AC to the terminal labeled + and the one diagonally from it resulted in a perfectly working bridge. Testing the other one revealed exactly the same situation!
Sherman
-----------------------
Don't touch that! Its hot!
Another strange PS effect ??
Hello guys,
I can contribute another strage problem with my GC (noniverting):
When I switch on power, I have some 100Hz-hum in the speakers. I could almost rule out grounding problems since I tested with a 1:1 mains transformer, and additionally I checked what happened with the input grounded. In fact, the hum remains, and I found some 20mV (pp) on the supply rails.
I have 2200uF // 100nF right next to the LM3876 for each rail. Additionally, I checked with a pair of 47000 uF caps next to the rectifier. Those caps only lowered the noise voltage to abt. 10 mV (pp), bus there is still a lot of audible hum at low signal levels.
The transformer is a 22V-0V-22V-toroid, followed by a single bridge (center tap of transformer connected to gnd)
Besides that, the GC performs quite nicely!
Does anyone of you have an idea what could be wrong?
Greetings from Germany
Herman
Hello guys,
I can contribute another strage problem with my GC (noniverting):
When I switch on power, I have some 100Hz-hum in the speakers. I could almost rule out grounding problems since I tested with a 1:1 mains transformer, and additionally I checked what happened with the input grounded. In fact, the hum remains, and I found some 20mV (pp) on the supply rails.
I have 2200uF // 100nF right next to the LM3876 for each rail. Additionally, I checked with a pair of 47000 uF caps next to the rectifier. Those caps only lowered the noise voltage to abt. 10 mV (pp), bus there is still a lot of audible hum at low signal levels.
The transformer is a 22V-0V-22V-toroid, followed by a single bridge (center tap of transformer connected to gnd)
Besides that, the GC performs quite nicely!
Does anyone of you have an idea what could be wrong?
Greetings from Germany
Herman
Is it soft 50 Hz hum or hard 100 Hz with harmonics?
100 Hz, which I'll guess you have => how have you connected the center tap, smoothing caps, speaker ground, signal ground?
Think like this:
signal ground
speaker ground
caps ground
transformer ground (center tap)
This is the order you must connect the ground in.
The thing which causes the hum is charging currents in the smoothing caps. A couple of milliohms and 1 A in the charging peaks (just an example) => millivolts in hum!
Can you take a photo or do a simple sketch?
100 Hz, which I'll guess you have => how have you connected the center tap, smoothing caps, speaker ground, signal ground?
Think like this:
signal ground
speaker ground
caps ground
transformer ground (center tap)
This is the order you must connect the ground in.
The thing which causes the hum is charging currents in the smoothing caps. A couple of milliohms and 1 A in the charging peaks (just an example) => millivolts in hum!
Can you take a photo or do a simple sketch?
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