Hello,
I'm trying to build the circuit shown here
to be powered with a 9-volt battery. I want to build this in stereo, so I'm wondering what is the best way to power two channels. Do I have two independent channels? Two batteries wired together to make 18V and the channels jumpered together? 1 9-volt to jumpered channels? +9V into one channel and -9V into the other?
Thank you in advance.
I'm trying to build the circuit shown here
to be powered with a 9-volt battery. I want to build this in stereo, so I'm wondering what is the best way to power two channels. Do I have two independent channels? Two batteries wired together to make 18V and the channels jumpered together? 1 9-volt to jumpered channels? +9V into one channel and -9V into the other?
Thank you in advance.
In this scheme, for each channel it is necessary to use a separate battery . 2 channel - 2 battery . Just make 2 identical circuits , as shown in the photo
This scheme was used in the serial device Marcof - there were 2 channels with two separate batteries . Marcof Electronics Custom Electronics - - Product Brochure - Vinyl Engine
This scheme was used in the serial device Marcof - there were 2 channels with two separate batteries . Marcof Electronics Custom Electronics - - Product Brochure - Vinyl Engine
Question about ground vs. chassis ground
Hello. I'm trying to make a board for this circuit. The board will be placed into a metal enclosure and use RCA connectors. Since the RCA input ground terminal will be in contact with the metal chassis of the enclosure, I think I'll need to connect the RCA in/chassis ground/circuit ground like this:
Is that correct?
For the output, is there any point in connecting an additional wire from the RCA ground terminal to the circuit ground on the board, as shown? If so, will it mess things up that there's another chassis ground point on the other side of the circuit? Do I need to insulate the RCA out ground from the chassis?
As I design the board, are there components that should not be close to one another? My first guess is that, since it's all DC, the placement of the circuit elements isn't as critical, and I can pack them all pretty close to one another.
I'd appreciate hearing your perspective on how I should populate the board.
Thanks in advance
Hello. I'm trying to make a board for this circuit. The board will be placed into a metal enclosure and use RCA connectors. Since the RCA input ground terminal will be in contact with the metal chassis of the enclosure, I think I'll need to connect the RCA in/chassis ground/circuit ground like this:
Is that correct?
For the output, is there any point in connecting an additional wire from the RCA ground terminal to the circuit ground on the board, as shown? If so, will it mess things up that there's another chassis ground point on the other side of the circuit? Do I need to insulate the RCA out ground from the chassis?
As I design the board, are there components that should not be close to one another? My first guess is that, since it's all DC, the placement of the circuit elements isn't as critical, and I can pack them all pretty close to one another.
I'd appreciate hearing your perspective on how I should populate the board.
Thanks in advance
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On your circuit there are errors . C1 is not connected properly - make as in the original scheme . For the transistor 4401 is equivalent to the pair is the transistor 4403 . Apply the layout of elements in the product Marcof ( download the brochure on my link ) - it's got pictures inside . It was a serial product .
Thank you for helping me. I changed the schematic so C1 is as in the original scheme. Does this look better?
If this is correct, I don't understand the difference between circuit ground and chassis ground. Is it okay that they are the same? Or do I need to insulate the ground tabs on the connectors from the chassis?
Also, I'm not sure what you mean when you said
If this is correct, I don't understand the difference between circuit ground and chassis ground. Is it okay that they are the same? Or do I need to insulate the ground tabs on the connectors from the chassis?
Also, I'm not sure what you mean when you said
Can you please explain?
The transistor 4403 is a complementary pair of transistor 4401 . They have the same electrical parameters . Using another transistor may impair the symmetry of the modes of operation of the circuit . This may affect the sound quality .In the original Marshall Leach scheme is applied to the transistor 4401 and 4403 .......The scheme - now everything is correct . Also it would be correct to connect the ground of the input connector to the metal chassis of your device without capacitor C1 .It will work ....
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Thank you for your input! Is it okay to connect the ground of the RCA output to the chassis without wiring it to the board, if the input is connected to the board through C1? What is the advantage of connecting both input and output grounds to both the chassis and the board?
The earth pin of the connector should connect to the ground bus on the PCB . Also - the ground bus must be connected to the metal chassis . This principle of shielding in the audio . Connect ground bus of the Board with the metal chassis at one point only - near the input connector . So do the audio . Done so in most low-noise audio devices .
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If I have the earth pin of input AND the earth pin of the output both connected to the ground bus on the PCB, isn't that connecting the ground bus of the pcb to the metal chassis at two points (the input and the output)? Or does that not matter?
Also, when I double the circuit for stereo, does it matter if I have a power indicator LED and resistor in parallel with the circuit on one channel and not the other? Or should I include the resistor and LED in both channels even if I intend to only have 1 LED visible?
Don't do dual plug earthen bus printed circuit Board with metal chassis . This can lead to additional rumble ( formation of the ground loop ) . Connect ground bus of the Board at one point to the chassis . Take this point from the input of the Board ......The indicator ...you Can apply only one indicator . Try to apply the indicator with a small current , or flashing . This will reduce the battery drain . The value of the resistor for the indicator try to choose a large . Battery is connected in the signal circuit and the indicator should not affect the signal . Ground bus on the PCB do not make a closed - make the breaking of the ground track . Here is a sample of a well-functioning MC - preamp . Please note on the earthen path - it is wide and not closed ..... . DSCF4847а - Vinyl Engine ......MC-preamp - inside ( 5 ) - Vinyl Engine .....MC-preamp - rear panel ( 2 ) - Vinyl Engine ....This preamp on the scheme of Salas - he published this scheme on this website .
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That is very helpful. Thank you. For the output jacks, should I connect those to the chassis with no wires leading to the board? Or should I insulate the connector so it is connected to the circuit ground, but not the chassis?
Usually there are multiple varieties that will work.
If you were to put inputs and outputs on a common backplate next to each other and the jacks make good electrical contact with it, you could use that as a star point to build up your "ground tree".
The original design presumably used output jack ground as the star point (or at least only attached chassis ground there), then kept input ground isolated from chassis, with only C1 making a connection at RF for better shielding at these frequencies (due to rather high inductance, star grounding does not work too well at RF). These kinds of designs used to be common but they have their problems. RF shielding tends to be less effective, and the more connections you have, the more of a headache assembly becomes.
If you were to put inputs and outputs on a common backplate next to each other and the jacks make good electrical contact with it, you could use that as a star point to build up your "ground tree".
The original design presumably used output jack ground as the star point (or at least only attached chassis ground there), then kept input ground isolated from chassis, with only C1 making a connection at RF for better shielding at these frequencies (due to rather high inductance, star grounding does not work too well at RF). These kinds of designs used to be common but they have their problems. RF shielding tends to be less effective, and the more connections you have, the more of a headache assembly becomes.
If I'm not mistaken, the original circuit put the chassis ground on the input side. Is it better to make a star point out of the two input and output connectors or to try to insulate one connector from making contact with the metal chassis and then wiring that one to circuit ground? If I do the star point, do I still need to run a wire from the output ground to the board? I'm having a hard time of seeing what that would accomplish.
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