Dear all;
Got this kit off e-bay for a few dollars.
Decided to go for the chip amp power supply because this is so weird look at schematic ...
Any ideas I I would wire this on a "Typical Avel Torroid"
Brown/Grey Blue/Violet on input
Black/red and orange/yellow on out to give 24-0 and 24-0, but then what on input.
Is ground really the chassis ground, or 0??
The Amp board itself looks pretty straight forward.
Board
Schematic
Got this kit off e-bay for a few dollars.
Decided to go for the chip amp power supply because this is so weird look at schematic ...
Any ideas I I would wire this on a "Typical Avel Torroid"
Brown/Grey Blue/Violet on input
Black/red and orange/yellow on out to give 24-0 and 24-0, but then what on input.
Is ground really the chassis ground, or 0??
The Amp board itself looks pretty straight forward.
Board
Schematic
The transformer that you mentioned is having two secondaries of 24 volts each but the board is designed for centre tapped transformer. In order to use the board, you shold connect 0 of one secondary to 24 of other secondary.
Zero and ground are relative terms. Once you connect the designated Zero terminal to the bridge rectifier, you cannot consider it to be ground or chassis. However centre tap will be Zero volts for all circuit purposes, even if 24 V end is one of the wires.
For connecting primary, you have to be sure. Better provide more details as on the trnsformer.
Gajanan Phadte
Zero and ground are relative terms. Once you connect the designated Zero terminal to the bridge rectifier, you cannot consider it to be ground or chassis. However centre tap will be Zero volts for all circuit purposes, even if 24 V end is one of the wires.
For connecting primary, you have to be sure. Better provide more details as on the trnsformer.
Gajanan Phadte
.
The problem is that the schematic you have omitted the center tap on the power supply transformer. Added that.
CAUTION: Google your exact Avel model number to confirm the color codes.
<< Is ground really the chassis ground, or 0?? >>
No. Ground is one thing, chassis ground is another thing.
Unfortunately, the terms are used confusingly. Circuit ground is the zero-volt point on the circuit, and only that. Zero volts meaning that all circuit voltages are measured from that one point. That's the definition of circuit ground, the point from which all other voltages are measured.
So-called chassis ground is different. The chassis is connected to the third prong of the electrical cord that plugs into the wall (because you connect it that way). This prong is then connected, through the building wiring, literally to ground, the planet earth. The electric company takes care of this.
This connection to planet earth we take as zero volts. So since circuit ground is connected through the chassis to planet earth, theoretically every electrical circuit in the world has the same zero-reference point: the planet earth itself.
The bottom line is that there's one circuit ground point only, and that one point is then bonded (connected) to the chassis, also at one point only. All shipshape.
In a sidbar, connections to earth ground are correctly called "bonding." As in "the chassis is bonded to earth." But such terms as "chassis ground" and "safety ground" are in such widespread usage that there's little chance of ever changing that.
Still in a sidebar, you'll hear or read about various "ground lift" methods that don't bond/connect circuit ground directly to the chassis. You'll use your own judgment on those, of course.
.
The problem is that the schematic you have omitted the center tap on the power supply transformer. Added that.
CAUTION: Google your exact Avel model number to confirm the color codes.
<< Is ground really the chassis ground, or 0?? >>
No. Ground is one thing, chassis ground is another thing.
Unfortunately, the terms are used confusingly. Circuit ground is the zero-volt point on the circuit, and only that. Zero volts meaning that all circuit voltages are measured from that one point. That's the definition of circuit ground, the point from which all other voltages are measured.
So-called chassis ground is different. The chassis is connected to the third prong of the electrical cord that plugs into the wall (because you connect it that way). This prong is then connected, through the building wiring, literally to ground, the planet earth. The electric company takes care of this.
This connection to planet earth we take as zero volts. So since circuit ground is connected through the chassis to planet earth, theoretically every electrical circuit in the world has the same zero-reference point: the planet earth itself.
The bottom line is that there's one circuit ground point only, and that one point is then bonded (connected) to the chassis, also at one point only. All shipshape.
In a sidbar, connections to earth ground are correctly called "bonding." As in "the chassis is bonded to earth." But such terms as "chassis ground" and "safety ground" are in such widespread usage that there's little chance of ever changing that.
Still in a sidebar, you'll hear or read about various "ground lift" methods that don't bond/connect circuit ground directly to the chassis. You'll use your own judgment on those, of course.
.
Attachments
And now for some photos ....
Based on the above images, I have DRY wired this, that is I have not tried power just yet ....
Comments appreciated before mistakes are made...
a real photo, no need to go to the net
I would wire the 110V inputs on the other side of this block
I expect the center pair to the zero reference voltage, black +18, yellow -18V
Thanks for the replies
Dave
Based on the above images, I have DRY wired this, that is I have not tried power just yet ....
Comments appreciated before mistakes are made...
a real photo, no need to go to the net
I would wire the 110V inputs on the other side of this block
I expect the center pair to the zero reference voltage, black +18, yellow -18V
Thanks for the replies
Dave
Last edited:
Yet another question ... I often see images where the strips on the terminals are "bridged" by a small ceramic capacitor rather than just using the pass through of the terminal block, anyone care to comment about this?
Thanks;
Dave
Thanks;
Dave
To expand a bit on gmphadte's reply, the capacitors you're talking about are C9 and C10 on your circuit diagram.
However, the right place for these is very close to C7 and C8, respectively, on your circuit diagram. Similar capacitors added elsewhere, such as across any terminal block connections, were added to that specific circuit for some specific reason.
.
Last edited:
post1 lower diagram:
remove C1, C2, C3, C4, C9 and C10.
Retain C5, C6, C7 and C8.
Remove LED1 and LED2 and reverse. The current must flow through the LED to allow the LED to indicate.
LED do not have a high reverse voltage capability. You may have already damaged them. Check they still work before soldering back in.
+V, GND, -V are the three feeds to the amplifier. Twist them as a triplet all the way from the PSU to the amplifier.
The ground symbol at the other end goes to the centre tap of the transformer.
BUT !!!!
where is the centre tap? You show a single winding without a centre tap.
remove C1, C2, C3, C4, C9 and C10.
Retain C5, C6, C7 and C8.
Remove LED1 and LED2 and reverse. The current must flow through the LED to allow the LED to indicate.
LED do not have a high reverse voltage capability. You may have already damaged them. Check they still work before soldering back in.
+V, GND, -V are the three feeds to the amplifier. Twist them as a triplet all the way from the PSU to the amplifier.
The ground symbol at the other end goes to the centre tap of the transformer.
BUT !!!!
where is the centre tap? You show a single winding without a centre tap.
about 3 posts back up, bentsnake shows the center taps.
I have not populated the board yet, waiting on parts.
Odd that on a pretty "standard PCB Leds are labeled wrong, but things to happen.
Why do you suggest omiting the Caps except the big power ones?
Any comments on the photos of the torroid?
Thanks for the input
Dave
I have not populated the board yet, waiting on parts.
Odd that on a pretty "standard PCB Leds are labeled wrong, but things to happen.
Why do you suggest omiting the Caps except the big power ones?
Any comments on the photos of the torroid?
Thanks for the input
Dave
.
Son of a gun, the LEDs are shown backward. Correctly, the arrow points to the negative (or most-negative) part of the circuit. R1 and R2 don't have to be changed, their location doesn't matter as long as they're present.
C1-C4 are bypass capacitors for the 4 rectifiers (or single bridge rectifier, whichever you use). Their function is to clean up tiny voltage irregularities that occur in the normal operation of any diode. These are often left out (i.e. ignored), but are recommended by some gurus.
C9 and C10 have a similar function, cleaning up the voltage across the capacitor bank (C5, C6, C7, C8). These are normally part of any power supply, I don't know why anybody would suggest leaving them out.
.
Son of a gun, the LEDs are shown backward. Correctly, the arrow points to the negative (or most-negative) part of the circuit. R1 and R2 don't have to be changed, their location doesn't matter as long as they're present.
C1-C4 are bypass capacitors for the 4 rectifiers (or single bridge rectifier, whichever you use). Their function is to clean up tiny voltage irregularities that occur in the normal operation of any diode. These are often left out (i.e. ignored), but are recommended by some gurus.
C9 and C10 have a similar function, cleaning up the voltage across the capacitor bank (C5, C6, C7, C8). These are normally part of any power supply, I don't know why anybody would suggest leaving them out.
.
Um? In previous posts you've insisted that such capacitors be included. New policy?
.
The LED's could be an excellent safety feature, but only if installed in correct polarity (schematic is backwards). Those will be quite good if you get them to light up.
Instead of snubbing the bridge rectifier like an fm tuner, a more useful approach for power amp supply, may be snubbing the transformer secondary. Center tap configuration makes it easy, because just one snubber for the whole thing. That is one RC across the one transformer secondary (snubber doesn't connect to 0v/CT).
Snubbing checklist:
The caps aren't any larger than the need.
Doesn't connect to 0v by solid link.
The series resistor (or roll-off frequency resistance) does most of the work.
Different size caps aren't directly paralleled without ballast in-between.
C9 and C10 fail the whole checklist.
Instead of snubbing the bridge rectifier like an fm tuner, a more useful approach for power amp supply, may be snubbing the transformer secondary. Center tap configuration makes it easy, because just one snubber for the whole thing. That is one RC across the one transformer secondary (snubber doesn't connect to 0v/CT).
Snubbing checklist:
The caps aren't any larger than the need.
Doesn't connect to 0v by solid link.
The series resistor (or roll-off frequency resistance) does most of the work.
Different size caps aren't directly paralleled without ballast in-between.
C9 and C10 fail the whole checklist.
finally got around to setting up this stuff on my torroidal transformer.
Based on the info I was getting here, I decided to get an XY kit rather than mess around with these boards.
That however is a topic to be put in the right thread ...
Wired exactly as the pictures in the above, except added in a switch
The proof is in the pudding so to say ....
I used a multimeter each step of the way, and voltages were made right before I moved on to the next step in the circuit.
One wiring misstep that that method caught.
Read up on the bulb tester, but I did not build one. I was OK with the DMM methods.
This is more or less described on the Chip amp site.
Dave
Based on the info I was getting here, I decided to get an XY kit rather than mess around with these boards.
That however is a topic to be put in the right thread ...
Wired exactly as the pictures in the above, except added in a switch
The proof is in the pudding so to say ....
I used a multimeter each step of the way, and voltages were made right before I moved on to the next step in the circuit.
One wiring misstep that that method caught.
Read up on the bulb tester, but I did not build one. I was OK with the DMM methods.
This is more or less described on the Chip amp site.
Dave
Love the heavy duty terminal blocks shown throughout this thread! Those are so much better than usual.
- Status
- Not open for further replies.