Generaly you will only NEED one bridge per mono-block, however if you realy wanted to and had 'proper' dual secondaries you could use two, but I doubt that this would be necesary here and is something that you don't see too often in high power amps as it will just add more complexity and expense.
Matching of FET's
OK Chaps - I have one of those Atlas Component analysers and am prepared to do the first cut FET matching (it matches at too low a bias current for our purposes (about 2ma i think), so 2 lots of matching needs to be done).
I suggest using the analyser to get a starting point, then building a matching rig with the FET biased at 1 amp. with both figures we'll be able to get fets that not only match well at their bias value, but also track well to that point as well.
I have an account with RS components and can order IRFP044N's in TO247 cases from RS components at £1.89 each in quantities of 100 - Can we finalise quantities, i'll put a purchase through and do the initial matching and a volunteer can do the the higher current matching - volunteers please?
OK Chaps - I have one of those Atlas Component analysers and am prepared to do the first cut FET matching (it matches at too low a bias current for our purposes (about 2ma i think), so 2 lots of matching needs to be done).
I suggest using the analyser to get a starting point, then building a matching rig with the FET biased at 1 amp. with both figures we'll be able to get fets that not only match well at their bias value, but also track well to that point as well.
I have an account with RS components and can order IRFP044N's in TO247 cases from RS components at £1.89 each in quantities of 100 - Can we finalise quantities, i'll put a purchase through and do the initial matching and a volunteer can do the the higher current matching - volunteers please?
Hi, as far as the MOSFETS go, I believe that Reichelt in germany stocks them for only 1.20 euros (about 81p), so it may make more sense to try and order from here, as this will half the initial cost of the devices. Although we could expect the shipping to be a little higher (we shouldn't have to pay improt duty or tax tough as they are from in the EU right?) than RS (which I guess would be zero).
Matching
Jason, I am happy to offer the time, if someone is able to build and loan the rig to test the FETs.
I will be happy to look at a Reichelt order to save some cash, if that is what is wanted (credit card ready and a fluent german-speaking friend to smooth the bumps!!).
I do sense that we are moving forward! 🙂
Cheers
Jon 😀
Jason, I am happy to offer the time, if someone is able to build and loan the rig to test the FETs.
I will be happy to look at a Reichelt order to save some cash, if that is what is wanted (credit card ready and a fluent german-speaking friend to smooth the bumps!!).
I do sense that we are moving forward! 🙂
Cheers
Jon 😀
Right, I have had a quick bash at a rectifier PCB using the BYW99W-200's but without any of the snubber caps at the moment. I'm off to bed now, but I should be able to fit the snubbers on here quite easily when I have spare few minutes, and see if I cant make the thing any smaller so it gets a bit cheeper to make. This current revision would cost just over £3.00 per PCB for a single sided board, about another £6.20 for the diodes and about £4.20 for the heatsinks (so about £13.50 in all, which isn't too bad).
For the next bersions, the cost of the diodes and heatsinks will remain constant, and as long as I can keep the board single sided when I add the snubbing caps, that should still be the same price, so you would only need to add a pound or so for a couple of decent little caps to put on if you wnated to.
For the next bersions, the cost of the diodes and heatsinks will remain constant, and as long as I can keep the board single sided when I add the snubbing caps, that should still be the same price, so you would only need to add a pound or so for a couple of decent little caps to put on if you wnated to.
Attachments
You can see (just, if you ignore all of the bits stuck on the board) the silkscreen, although the boards looked a lot better in the flesh and were pretty decent quality:
I guess you could also say that this was the first amp that I built (after the rather messy prototype; it has a switched attenuator and everything). Shame it was only to produce white noise.
Top:
I guess you could also say that this was the first amp that I built (after the rather messy prototype; it has a switched attenuator and everything). Shame it was only to produce white noise.
Top:
Attachments
circuit boards
Fantastic BP ...... I would be in for 3 boards.............+ associated components.
I am really impressed with the quality..............+ layout ...this is seriously professional! Well done!!!
Fantastic BP ...... I would be in for 3 boards.............+ associated components.
I am really impressed with the quality..............+ layout ...this is seriously professional! Well done!!!
Ok, I have gone back and redone the layout to include snubber capacitors and resistors (these can be left out if you want, or run just with the caps so long as you put a wire jumper where the resistor is supposed to go). I also have some rough specs on what the board should be bale to handle in terms of curent with the selected diodes and heatsinks. The SK104 heatsinks have a thermal resistance of 9 deg/w, and the maximum junction temp for the diodes is 150 degrees, so with a Vf of about 0.9V, you should be able to run at 14A for a room temp of 25 degrees easily.
I have also worked out the rough pricing for the total parts list and boards, assuming we get enough parts to make about 25 boards (to get the price breaks on the components):
PCB - £3.00 x 1
diodes - £1.69 x 4 (RS, 446-9908)
Heatsinks - £0.91 x 4 (Maplin, RN82)
Caps - £0.22 x 4 (RS, 414-7620)
resistors - £0.04 x 4 (Rs, 148-269)
conectors - £0.03 x 4 (RS, 534-834)
Total (not inc any postage) ~ £14.60
So, if people are interested this could be something else we could look at getting together (I'd be happy to get the boards sorted allong with the heatsinks, and Jason mentioned he had an RS account, so perhaps he would be able to help sort out those parts?).
I have also worked out the rough pricing for the total parts list and boards, assuming we get enough parts to make about 25 boards (to get the price breaks on the components):
PCB - £3.00 x 1
diodes - £1.69 x 4 (RS, 446-9908)
Heatsinks - £0.91 x 4 (Maplin, RN82)
Caps - £0.22 x 4 (RS, 414-7620)
resistors - £0.04 x 4 (Rs, 148-269)
conectors - £0.03 x 4 (RS, 534-834)
Total (not inc any postage) ~ £14.60
So, if people are interested this could be something else we could look at getting together (I'd be happy to get the boards sorted allong with the heatsinks, and Jason mentioned he had an RS account, so perhaps he would be able to help sort out those parts?).
Attachments
Nice Work!!
Hi,
Count me in for 2 definitely!!
I have the 860s and will use them for my GC project with the Avondale boards.
Cheers
Jon😀
Hi,
Count me in for 2 definitely!!
I have the 860s and will use them for my GC project with the Avondale boards.
Cheers
Jon😀
Anti surge
Your work on the hp rectifier ..... great as I said before count me in for 3.
In the preamp I built ....... a Ben Duncan job he incorporated a very effective inline surge filter using vdrs etc. This has been discussed @ pass labs......take a look at this thread........
correctly configured VDR's.....seem to do a great job.
http://www.geocities.com/jonrisch/surge.htm
I am also aware that a current inrush limiter may be required , for those with a 1000va tranny.....I would think it highly advisable
I know when I switch on one of my amps with a 500va tranny....it makes the lights dim in the house for a split second....I believe torroids have a high current surge on switch on.....
here is an section I have pasted.......
The CL 60 has a cold resistance of ~10ohms. It suggested that these be used in each of the 120VAC primaries that would make up your 240VAC or if you don't have this type of transformer, use 2 - CL 60's in series to effectively give you ~20ohms at power up. This will limit the primaries to 240/20 = 12A. Or as Peter suggests, use the CL 70 with a cold resistance of 15ohms.
BP what do you think?????? Maybe we could do a circuitboard put together that could incorporate the filter + the current inrush...limiters.
Your work on the hp rectifier ..... great as I said before count me in for 3.
In the preamp I built ....... a Ben Duncan job he incorporated a very effective inline surge filter using vdrs etc. This has been discussed @ pass labs......take a look at this thread........
correctly configured VDR's.....seem to do a great job.
http://www.geocities.com/jonrisch/surge.htm
I am also aware that a current inrush limiter may be required , for those with a 1000va tranny.....I would think it highly advisable
I know when I switch on one of my amps with a 500va tranny....it makes the lights dim in the house for a split second....I believe torroids have a high current surge on switch on.....
here is an section I have pasted.......
The CL 60 has a cold resistance of ~10ohms. It suggested that these be used in each of the 120VAC primaries that would make up your 240VAC or if you don't have this type of transformer, use 2 - CL 60's in series to effectively give you ~20ohms at power up. This will limit the primaries to 240/20 = 12A. Or as Peter suggests, use the CL 70 with a cold resistance of 15ohms.
BP what do you think?????? Maybe we could do a circuitboard put together that could incorporate the filter + the current inrush...limiters.
I'm sure it wouldn't be too much bother to put together a PCB for a filter and inrush current limiter. If people can decide what they would want (what sort of filter? Just to kill voltage spikes or to actualy filter the mains a bit? and what sort of inrush curent limit? The VDR would probably be fine in this case as there is a fairly constant curent draw, but it wouldn't be so good if you wnated to use the board for a clas AB amp, as the extra supply impedance may have an effect on the PSU output impedance).
However, if all you want to add to the supply is the VDR and a couple of suppressors, then I would say that you will be just as well off with hardwiring them in, as it will only be four joints.
However, if all you want to add to the supply is the VDR and a couple of suppressors, then I would say that you will be just as well off with hardwiring them in, as it will only be four joints.
current inrush
Well I personally would only want to double clamp the mains in with vdrs for very basic spike suppression..............+ incorporate a limiter for current inrush.....however I am open to suggestions...having lived with an amp that banged and popped at the slightest provocation....I want this to be right....
I'm not sure what value to use.........can you advise based on 1000va.........????
As for circuit board.....my thoughts were that it would keep everything neat.........and possibly it could be a simple thing to sell in future..................
Well I personally would only want to double clamp the mains in with vdrs for very basic spike suppression..............+ incorporate a limiter for current inrush.....however I am open to suggestions...having lived with an amp that banged and popped at the slightest provocation....I want this to be right....
I'm not sure what value to use.........can you advise based on 1000va.........????
As for circuit board.....my thoughts were that it would keep everything neat.........and possibly it could be a simple thing to sell in future..................
Re: current inrush
If only I had the spare cash, there would be hundreds of PCB's lying around in my room.
My girlfriend is going to hate when I get a proper job and actualy have the money to do this all the time:
D3 said:
If only I had the spare cash, there would be hundreds of PCB's lying around in my room.
My girlfriend is going to hate when I get a proper job and actualy have the money to do this all the time:
Hi,
I'd be happy to pay the extra for the PCBs.
Also, now we are talking about current inrush etc, is there a bleeder for the caps in the AX? If not, how about a small board to deplete the rails after power off?
Sorry, wrong teminology, but i'm sure you'll get my point.... 🙄
Safety first!!
😀
Cheers
Jon 🙂
I'd be happy to pay the extra for the PCBs.
Also, now we are talking about current inrush etc, is there a bleeder for the caps in the AX? If not, how about a small board to deplete the rails after power off?
Sorry, wrong teminology, but i'm sure you'll get my point.... 🙄
Safety first!!
😀 Cheers
Jon 🙂
Trannies.....
Looks like these will come in at 29.11 plus vat for potted, banded items. Still good value. I'm still in for 3 of the 1000VA
I would also like to add 2 x 15va at 15 - 0 - 15 so I can make a 12vdc pwer supply for my Nixon DAC (completed and running off batteries) and my to be build DDDAC. Banded and potted would be good.
Cheers
Jon
Looks like these will come in at 29.11 plus vat for potted, banded items. Still good value. I'm still in for 3 of the 1000VA
I would also like to add 2 x 15va at 15 - 0 - 15 so I can make a 12vdc pwer supply for my Nixon DAC (completed and running off batteries) and my to be build DDDAC. Banded and potted would be good.
Cheers
Jon
Trannies
D3, could I also specify that the 2 x 15 VA trannies have dual secondaries? I would like to be able to use 2 bridges per supply for later superregulation.....
If that's not a cheek. If it makes thinkgs complicated, I'll order from Airlink direct (Just wanted them all in the same box to save a bit on postage).
Cheers
Jon 🙂
D3, could I also specify that the 2 x 15 VA trannies have dual secondaries? I would like to be able to use 2 bridges per supply for later superregulation.....
If that's not a cheek. If it makes thinkgs complicated, I'll order from Airlink direct (Just wanted them all in the same box to save a bit on postage).
Cheers
Jon 🙂
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