Krill mod ps
Yes I'm using Steve's board.
Here is what I am thinking, will this work or have I got it all wrong??
What concerns me is ground- Steve has the secondaries tied together and I have the outputs of the regulators tied together so I am not sure it will work.
Of course there may be other problems too.
Yes I'm using Steve's board.
Here is what I am thinking, will this work or have I got it all wrong??
What concerns me is ground- Steve has the secondaries tied together and I have the outputs of the regulators tied together so I am not sure it will work.
Of course there may be other problems too.
An externally hosted image should be here but it was not working when we last tested it.
More questions
Sorry to keep bothering everyone.
Here are some more questions as I stuff Steve's boards. While the silk is hard to read, the boards are very luxorious and there is lots of room for the components.
1. I notice that the BOM on post 252 does not list R4 and R5, these are 1/4 watt 33 ohm resistors right?
2. There is no R25 correct? (did I miss it, cannot find it on the BOM or schematic)
3. For R10, it is supposed to connect the base of Q2 to ground according to the schematic. The board has two possible nearby holes to put in the connection on the other side of the resistor. One hole leads to C22 (the small one, which according to the stuff guide is to be shorted). The other hole is grounded on the big fat ground trace. Have I got this right and can it just connected one hole up to the big fat ground trace?
4. What is with C22 (the small one under C16), is it to be shorted via a jumper (J4 in the stuffit pic)?
Sorry to keep bothering everyone.
Here are some more questions as I stuff Steve's boards. While the silk is hard to read, the boards are very luxorious and there is lots of room for the components.
1. I notice that the BOM on post 252 does not list R4 and R5, these are 1/4 watt 33 ohm resistors right?
2. There is no R25 correct? (did I miss it, cannot find it on the BOM or schematic)
3. For R10, it is supposed to connect the base of Q2 to ground according to the schematic. The board has two possible nearby holes to put in the connection on the other side of the resistor. One hole leads to C22 (the small one, which according to the stuff guide is to be shorted). The other hole is grounded on the big fat ground trace. Have I got this right and can it just connected one hole up to the big fat ground trace?
4. What is with C22 (the small one under C16), is it to be shorted via a jumper (J4 in the stuffit pic)?
I agree with Steve . If it doesn't, you can connect a pair of out-of-phase ends of the secondaries together and to the point marked GND on your addition and keep the rest connected as you show. Basically you end up with a center tap secondary with a full-wave bridge between each half of the secondary.
Do you mean R3 and R4? Yes they are 33 ohm.
There is no R25.
I think post 117 should answer your other questions. Those extra connections allow you dc-couple or ac-couple the feedback to ground. Right around that post, I've made some comments that might help although Steve corrected what I was referring to with his posts 251 and 252.
Good luck!
Do you mean R3 and R4? Yes they are 33 ohm.
There is no R25.
I think post 117 should answer your other questions. Those extra connections allow you dc-couple or ac-couple the feedback to ground. Right around that post, I've made some comments that might help although Steve corrected what I was referring to with his posts 251 and 252.
Good luck!
Thanks
You mean if it doesn't work that I should connect the centermost secondaries together and then connect this to GND as I have labeled?
I do not understand how you get the 90V out of 35 vac seconardies, but I trust that it happens (some kind of doubler or something?)
Correct, R3 and R4, thanks.
Thanks.
Here is what you said in #117 (just for everyone's reference. having no idea which way to go, I think I will DC couple (connect R10 to the big gnd trace). Does this mean that the small C22 need not be shorted/ you can "no connect" it?
- thanks
PH104 said:
You mean if it doesn't work that I should connect the centermost secondaries together and then connect this to GND as I have labeled?
I do not understand how you get the 90V out of 35 vac seconardies, but I trust that it happens (some kind of doubler or something?)
Correct, R3 and R4, thanks.
Thanks.
Here is what you said in #117 (just for everyone's reference. having no idea which way to go, I think I will DC couple (connect R10 to the big gnd trace). Does this mean that the small C22 need not be shorted/ you can "no connect" it?
- thanks
Hi lgreen --
Yes to the first question and you're right, it's a voltage doubler. Google "voltage doubler" and you should get plenty of info.
C22 is not necessary if you dc-couple as shown in Steve's schematic. So connect the end of R10 to the hole that goes to the ground trace and ignore C22 altogether. You do not need to jump it or anything else.
If you dc couple the feedback, you will amplify any dc that appears at the input of the amp from your source. If your source has no dc at the output (as it should), then it is fine to dc couple the feedback.
Hope this helps. And by the way -- nice website!
more questions
A couple of more questions.
1. There is a C2 below Q5 on the board but no C2 in the parts list. What goes here?
2. There is a D206 on the parts list, a D260 on the Stuff picture and a D26 (near C12) on the Board. Are these all the same?
3. On the board there appears to be a spot for resistor or something near "in" and "1" underneath R1. What goes here?
A couple of more questions.
1. There is a C2 below Q5 on the board but no C2 in the parts list. What goes here?
2. There is a D206 on the parts list, a D260 on the Stuff picture and a D26 (near C12) on the Board. Are these all the same?
3. On the board there appears to be a spot for resistor or something near "in" and "1" underneath R1. What goes here?
Here's what goes on --
1. C2 is an optional compensation capacitor. You probably won't need it. If you see oscillation or overshoot on square wave, try 10 or so picofarad there. There has been some discussion of this before. I can't remember if it was in this thread or the other Krill thread - I think this one.
2. There are two D26 on the board. The one near C12 is the D206 in the BOM. The D26 (the zener diode) on the BOM is the same as the ZD2 in the post 251 schematic.
3. Steve can provide more info here but the boards were designed with some flexibility. That's why there are 2 hole patterns for headers and why the feedback can be ac or dc coupled. The extra (unmarked) resistor pattern provides a connection to the inverting input of the amp. You can ignore it.
1. C2 is an optional compensation capacitor. You probably won't need it. If you see oscillation or overshoot on square wave, try 10 or so picofarad there. There has been some discussion of this before. I can't remember if it was in this thread or the other Krill thread - I think this one.
2. There are two D26 on the board. The one near C12 is the D206 in the BOM. The D26 (the zener diode) on the BOM is the same as the ZD2 in the post 251 schematic.
3. Steve can provide more info here but the boards were designed with some flexibility. That's why there are 2 hole patterns for headers and why the feedback can be ac or dc coupled. The extra (unmarked) resistor pattern provides a connection to the inverting input of the amp. You can ignore it.
thanks
Thanks, the boards are virtually done; case is done and PS was done but now...
I'm thinking of redoing the PS to be a single bridge driving both channels from 1 transformer which will be easier plug-in-replacement to interface with the boards than the dual bridge that I have now.
Is there any problem driving the 3 set of rectifiers (2 HV and the 1 LV power rectifier shared across 2 channels) from a single transformer? I am worried about 1 set hogging all the juice. I seem to recall that diodes really don't like being in parallel with each other.
Thanks, the boards are virtually done; case is done and PS was done but now...
I'm thinking of redoing the PS to be a single bridge driving both channels from 1 transformer which will be easier plug-in-replacement to interface with the boards than the dual bridge that I have now.
Is there any problem driving the 3 set of rectifiers (2 HV and the 1 LV power rectifier shared across 2 channels) from a single transformer? I am worried about 1 set hogging all the juice. I seem to recall that diodes really don't like being in parallel with each other.
Re: thanks
You should not have a problem with that. It is done all the time when both channels are in the same case.
lgreen said:
You should not have a problem with that. It is done all the time when both channels are in the same case.
Is it ok to or what is the problem with using 27 ohms for R3 and R4?
Since R3/R4 were not in the BOM I never ordered the 33 ohm resistors, but I do have 27 ohms.
Since R3/R4 were not in the BOM I never ordered the 33 ohm resistors, but I do have 27 ohms.
but you hold stock of all 6decades of E24 values in your preferred resistor type.lgreen said:
I hold 600mW or 250mW metal film 50ppm 1% in stock and many other more specialised types or values.
At £1.50 per hundred that amounts to just £216 of resistor stock.
Yeah, I just was looking through my box-o-stuff, there is no stockroom here!
Thanks PH104- you have email!
EDIT- I think I get it Andrew- are you saying that 27 ohm resistors 1% are actually 33 ohm resistors 20% or in other words if you bought 33 ohms you might get 27?
Thanks PH104- you have email!
EDIT- I think I get it Andrew- are you saying that 27 ohm resistors 1% are actually 33 ohm resistors 20% or in other words if you bought 33 ohms you might get 27?
For a minute I couldn't find them in my box. They're in today's mail to you. And you're welcome.
lgreen said:
You are the first to point this out. It is really hard to get these things perfect.
Phil,
Thanks for covering for me.
its ok
Steve- not a problem, I should have double checked anyway. I am grateful that you even provided a list with working part ##s which most people do not even attempt. I am not trying to be critical or snide, I appreciate all your help.
Just keep with me on these questions and thank you for your help so far.
PS has been rewired this morning with only 1 bridge, it should wire right into the boards.
Lets talk about inputs and outputs and connections
Input- R1 connects to "in" (right before holes #1-#6) so there appears to be no free hole for the input. should I solder something to its leg. Its hard to see if "In" connects to the hole next to it "1", does it?
Output- It appears that the output can and should be taken from any of the 4 alternative holes for R18-21. Right?
What are holes #1-6 for and #1-5 for? Should I put headers in there? Are they just for probing and testing?
Steve- not a problem, I should have double checked anyway. I am grateful that you even provided a list with working part ##s which most people do not even attempt. I am not trying to be critical or snide, I appreciate all your help.
Just keep with me on these questions and thank you for your help so far.
PS has been rewired this morning with only 1 bridge, it should wire right into the boards.
Lets talk about inputs and outputs and connections
Input- R1 connects to "in" (right before holes #1-#6) so there appears to be no free hole for the input. should I solder something to its leg. Its hard to see if "In" connects to the hole next to it "1", does it?
Output- It appears that the output can and should be taken from any of the 4 alternative holes for R18-21. Right?
What are holes #1-6 for and #1-5 for? Should I put headers in there? Are they just for probing and testing?
"Lets talk about inputs and outputs and connections
Input- R1 connects to "in" (right before holes #1-#6) so there appears to be no free hole for the input. should I solder something to its leg. Its hard to see if "In" connects to the hole next to it "1", does it?"
R2 is not used. Run the input to the hole for R2 that is adjacent to the "IN" end of R1.
"Output- It appears that the output can and should be taken from any of the 4 alternative holes for R18-21. Right?"
Those holes were provided so equal lengths of wire could be run from each output to the speaker out. I recommend you use at least one hole from each side of the board(say R18, R19), all four would be better.
"What are holes #1-6 for and #1-5 for? Should I put headers in there? Are they just for probing and testing?"
Those holes were added to the board so another board could be added to create an amp with built in crossover for multi amp systems. Holes 1 - 6 were for non inverting, 1 - 5 were for inverting.
Input- R1 connects to "in" (right before holes #1-#6) so there appears to be no free hole for the input. should I solder something to its leg. Its hard to see if "In" connects to the hole next to it "1", does it?"
R2 is not used. Run the input to the hole for R2 that is adjacent to the "IN" end of R1.
"Output- It appears that the output can and should be taken from any of the 4 alternative holes for R18-21. Right?"
Those holes were provided so equal lengths of wire could be run from each output to the speaker out. I recommend you use at least one hole from each side of the board(say R18, R19), all four would be better.
"What are holes #1-6 for and #1-5 for? Should I put headers in there? Are they just for probing and testing?"
Those holes were added to the board so another board could be added to create an amp with built in crossover for multi amp systems. Holes 1 - 6 were for non inverting, 1 - 5 were for inverting.
zobel
Thanks Steve (assume you meant not R2 but Rx?, the one kind of overlapping R1).
It would seem to me that the Zobel (R28 and C8) should be connected as close to the output as possible such that you kind of defeat its purpose by going from all 4 holes to the speaker terminal, vs. just the connection next to R19.
But if the design is 4 wires, its 4 wires you shall have.
Thanks Steve (assume you meant not R2 but Rx?, the one kind of overlapping R1).
It would seem to me that the Zobel (R28 and C8) should be connected as close to the output as possible such that you kind of defeat its purpose by going from all 4 holes to the speaker terminal, vs. just the connection next to R19.
But if the design is 4 wires, its 4 wires you shall have.