Crispy
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Post by Crispy on Mar 7, 2013 19:50:15 GMT
Thanks Marc. That was an interesting link, most of it went straight over my head, but I did use the calculator and it confirmed what you said. So 2mm dia(.8mm)? enameled copper wire wound around a 16mm dia object 16 times will give me the 2uh inductance required? It also said that the best results are usually obtained when the length of the coil is the same as its diameter? Does the resistor pass through the middle and then soldered to the legs of the inductor? I am asking this because there are 2 separate holes but they look like they are on the same track, also can the wire be left uncovered or is it better to be covered with shrink wrap? Sorry for all the questions. Cheers Chris
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Post by Deleted on Mar 7, 2013 20:16:21 GMT
Chris In these designs the actual value of the inductance is rarely critical Usually the copper wire has the ends stripped of the enamel, and a couple of turns wrapped around the resistor leads close to the body and soldered.If the resulting coil is wound tightly , shrink wrapping may not be essential to hold it all in place.Even a little epoxy resin will hold it in place. Regards Alex
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Post by Deleted on Mar 7, 2013 23:06:35 GMT
HI Chris, I'll send you enough to do the job and more, PM me you're address. I bought a bobbin of the stuff to do the inductors for the AK15W you'r welcome to a chunk. Regards, Alan Alex's right, epoxy out of the Pound shop is good enough and makes a solid job. Failing that Robin has used varnish..........I dipped a few in varnish works well takes longer to dry, no cost if you have an almost empty tin knocking about.
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 8, 2013 20:51:22 GMT
Marc, I had a quick trial run with some 2mm household wire wrapped around some 15mm copper tube, you will see from the pictures that this combination is far too big.
So I used the calculator again using 0.8mm 21awg wire around a 10mm dia object = 20.7 turns and the length sould be 16.6mm, this looks more like the size I am after to still get 2µH. Any chance you could double check this for me - TIA. Chris
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Crispy
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Post by Crispy on Mar 8, 2013 20:55:40 GMT
Chris In these designs the actual value of the inductance is rarely critical Usually the copper wire has the ends stripped of the enamel,and a couple of turns wrapped around the resistor leads close to the body and soldered. Regards Alex Alex, Is there any chance you can post me a pic as I am not 100% sure about the couple of turns wrapped around the resistor leads bit As they say a picture paints a thousand words. Chris
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Post by Deleted on Mar 8, 2013 22:40:24 GMT
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 9, 2013 11:51:52 GMT
Thanks for that Alex, that is how I would have done it but I wasn't sure
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Post by gommer on Mar 9, 2013 12:14:09 GMT
Hi Chris, When I fill in the tool with the following values: L=2µH, D=10.8mm, d=0.8mm, then it results in N=18.5 and l=14.8mm A 0,8mm wire wrapped around 10mm object has center to center diameter of 10.8mm. Just play around until you find something that suits. Mind you, the tool assumes perfect turn winding Cheers, Marc
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Post by Deleted on Mar 9, 2013 23:00:11 GMT
If you guys have an Inductance meter, see what happens to the inductance when you stick things (ferrous) in the middle of it and when you distort the windings. I found it interesting, but it probably doesn't matter one bit.
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 10, 2013 14:29:32 GMT
Hi Chris, When I fill in the tool with the following values: L=2µH, D=10.8mm, d=0.8mm, then it results in N=18.5 and l=14.8mm A 0,8mm wire wrapped around 10mm object has center to center diameter of 10.8mm. Just play around until you find something that suits. Mind you, the tool assumes perfect turn winding Cheers, Marc Thanks Marc, that sounds an even better calculation because it shows 18 ziz zags on the pcb and the length gives me plenty to play with. I think I am going to go with that. Cheers Chris
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 10, 2013 14:38:49 GMT
Just a quick update. Progress on both amps: Second amp with cross members in place and ready to drill holes for the front and back plates. PCB temporarily in place: The speaker grille fixings worked like a dream, the lid fits perfect every time and there is not too much resistance when I need to take it off - job well done There is still a hell of a lot of work to do on the cases yet before I can get around to spraying them.
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Crispy
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Post by Crispy on Mar 14, 2013 9:54:28 GMT
I am trying to source components for my boards and there are some things I am not sure of: Can anybody tell me what these two markings mean on my board. The red arrow is a resistor but I do not understand the value - 470 What? The yellow arrow has some sort of trimmer but what is it - obviously it is 1k TIA Chris
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Post by Deleted on Mar 14, 2013 10:17:52 GMT
I am trying to source components for my boards and there are some things I am not sure of: Can anybody tell me what these two markings mean on my board. The red arrow is a resistor but I do not understand the value - 470 What? The yellow arrow has some sort of trimmer but what is it - obviously it is 1k TIA Chris Hi Chris It's 470 ohms and the trimpot is a top adjust multiturn 1K trimpot. A 20 turn type or similar for fine adjustment. Make sure you order one with the pins in line, not in more of a " therefore" sign. Regards Alex
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 14, 2013 18:50:25 GMT
I am trying to source components for my boards and there are some things I am not sure of: Can anybody tell me what these two markings mean on my board. The red arrow is a resistor but I do not understand the value - 470 What? The yellow arrow has some sort of trimmer but what is it - obviously it is 1k TIA Chris Hi Chris It's 470 ohms and the trimpot is a top adjust multiturn 1K trimpot. A 20 turn type or similar for fine adjustment. Make sure you order one with the pins in line, not in more of a " therefore" sign. Regards Alex Hi Alex, Thanks for that info but I am still confused No problem with the trimpot, but with the resistor. You can see from the picture why I am confused - on another part of my board it shows a resistor of 470R which I thought was 470ohms, obviously both can't be 470ohms. Cheers Chris
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 14, 2013 19:08:21 GMT
Right guys, I now need some help with more components. Number 1 (red arrow). I know it is a bridge rectifier but do not have a clue to as what amps it should be for a 50 watt power amp, I have sourced some from Farnell but they come in 10 / 15 / 25 and 35 amps. The link below shows you what I have been looking at. uk.farnell.com/multicomp/gbpc35005w/bridge-rectifier-35a-50v/dp/1621702?Ntt=1621702Number 2 (yellow arrow), shows some sort of capacitor around the bridge rectifier but nothing more than the number 104? Number 3 (blue arrows) show some sort of transistor? again the only marking is on the board showing D667 & B647. Number 4 (green arrow) shows another capacitor near the zobel coil and again nothing more than the number 224? The orange arrows show the transistors - I have been able to work out which ones I need from a picture of a made up board, but I don't know which side of the board is NPN or PNP. Thanks guys all help greatly appreciated. Chris
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Post by Deleted on Mar 14, 2013 20:11:21 GMT
I'll have a bash Chris, but don't quote me! The main top transistors (+ve track) are NPN because they take power in at their Emitter (BCE) The lower main transistors (-ve track) are PNP because they take power in at their Collector. See link for my reasoning. For the remaining transistor on the top I gave up! Also using link as a better guide to where the tracks are going. The 104 cap is coding for 100nf and the 224 cap is coding for 220nf. See link for future ref. As for the bridge my bodger mentality would say go for the largest amp rating of 35 Oh, and the D667 & B647 are transistor model numbers.
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Crispy
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Post by Crispy on Mar 14, 2013 20:34:31 GMT
I'll have a bash Chris, but don't quote me! The main top transistors (+ve track) are NPN because they take power in at their Emitter (BCE) The lower main transistors (-ve track) are PNP because they take power in at their Collector. See link for my reasoning. For the remaining transistor on the top I gave up! Also using link as a better guide to where the tracks are going. The 104 cap is coding for 100nf and the 224 cap is coding for 220nf. See link for future ref. As for the bridge my bodger mentality would say go for the largest amp rating of 35 Oh, and the D667 & B647 are transistor model numbers. Cheers Chris, I will wait and see if Alex agrees that the transistors are NPN at the top and PNP at the bottom - I am pretty sure you will be correct but a second opinion is always welcome. Nice link to the capacitor coding site and thanks again I can start sourcing them. I also went with the bodger mentality that 35 amps has to be more stable, again I will see if Alex agrees first. D667 & B647 I know are transistors but I cannot seem to source them on Farnell's website Thanks for the help Chris.
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Post by Deleted on Mar 14, 2013 20:46:43 GMT
I'll have a bash Chris, but don't quote me! The main top transistors (+ve track) are NPN because they take power in at their Emitter (BCE) The lower main transistors (-ve track) are PNP because they take power in at their Collector. See link for my reasoning. For the remaining transistor on the top I gave up! Also using link as a better guide to where the tracks are going. The 104 cap is coding for 100nf and the 224 cap is coding for 220nf. See link for future ref. As for the bridge my bodger mentality would say go for the largest amp rating of 35 Oh, and the D667 & B647 are transistor model numbers. The output devices are ALL NPN 2SD1047. The TIP41 is the name of the device. It is an NPN type. Put a "B "in front of the C546 and C556. The A92 is an MPSA92. You will need to check the data sheets for both of those, and also those with a 2S in front of them to see if they are the same device
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Post by PinkFloyd on Mar 14, 2013 21:23:19 GMT
Right guys, I now need some help with more components. Number 1 (red arrow). I know it is a bridge rectifier but do not have a clue to as what amps it should be for a 50 watt power amp, I have sourced some from Farnell but they come in 10 / 15 / 25 and 35 amps. The link below shows you what I have been looking at. uk.farnell.com/multicomp/gbpc35005w/bridge-rectifier-35a-50v/dp/1621702?Ntt=1621702Number 2 (yellow arrow), shows some sort of capacitor around the bridge rectifier but nothing more than the number 104? Number 3 (blue arrows) show some sort of transistor? again the only marking is on the board showing D667 & B647. Number 4 (green arrow) shows another capacitor near the zobel coil and again nothing more than the number 224? The orange arrows show the transistors - I have been able to work out which ones I need from a picture of a made up board, but I don't know which side of the board is NPN or PNP. Thanks guys all help greatly appreciated. Chris Cheaper buying the real deal secondhand?
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 16, 2013 20:08:55 GMT
The output devices are ALL NPN 2SD1047. The TIP41 is the name of the device. It is an NPN type. Put a "B "in front of the C546 and C556. The A92 is an MPSA92. You will need to check the data sheets for both of those, and also those with a 2S in front of them to see if they are the same device Thanks Alex. I have now sourced all the components that I need except two resistors. I will post links to the components later and if you would be kind enough to check them for me it will be greatly appreciated. The problem is still with the two resistors showing 100 & 470 - I did a bit of research and hopefully came to the conclusion that 100 & 470 = 10ohm & 47ohm as 100R would be 100ohm & 470R would be 470ohm. Is this correct? TIA Chris BTW Alex, is the weather cooling down now, I noticed the Australian Grand Prix Qualifying was cancelled due to heavy rain, but hopefully the race will be on tomorrow
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 16, 2013 20:28:34 GMT
You are dead right Mike, I set myself a budget of £150 per amp and I have just looked on E-Bay at past listings and could have picked up a pair of XA-50's for £300. The only problem with that is I don't have £300 up front to buy these outright with work being crap + where's the fun in that Up to now I have spent £115 on both amps so I am well in budget at the mo. I am in no rush to build these amps and I will simply buy bits and bobs when funds permit - up to now I am really learning a lot from doing this project totally from scratch - a big learning curve for me, but I couldn't do it without the help of this forum and it's very kind and knowledgeable members. I now fully appreciate why Manufacturers charge so much for there gear and cannot believe how some can make such quality equipment at the price they charge - a good example is the Aune T1 - absolutely stunning cases and sound quality for imo peanuts.
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Post by Deleted on Mar 16, 2013 21:38:02 GMT
The output devices are ALL NPN 2SD1047. The TIP41 is the name of the device. It is an NPN type. Put a "B "in front of the C546 and C556. The A92 is an MPSA92. You will need to check the data sheets for both of those, and also those with a 2S in front of them to see if they are the same device Thanks Alex. I have now sourced all the components that I need except two resistors. I will post links to the components later and if you would be kind enough to check them for me it will be greatly appreciated. The problem is still with the two resistors showing 100 & 470 - I did a bit of research and hopefully came to the conclusion that 100 & 470 = 10ohm & 47ohm as 100R would be 100ohm & 470R would be 470ohm. Is this correct? TIA Chris BTW Alex, is the weather cooling down now, I noticed the Australian Grand Prix Qualifying was cancelled due to heavy rain, but hopefully the race will be on tomorrow Hi Chris If the PCB is actually marked 100 , and 470, then that should be their actual values. You would need to use a schematic or parts list to be 100% sure. It may just be a case of inconsistent PCB labelling, if they are meant to be resistors.. It was around 28c in Sydney again yesterday with another postcard perfect day, but so far this morning (8.18AM daylight saving time) it is overcast. Kind Regards Alex
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Post by Deleted on Mar 17, 2013 12:42:07 GMT
Hi Chris
''It may just be a case of inconsistent PCB labelling, if they are meant to be resistors''..
Yes that would make sense especially if they sell a built board where they will know what goes where so no need for any great care on their part.
I did have a Google round for the MF schematic but no luck on that front.
I’d say 100R and 470R and from experience they sometimes leave the ‘’R’’ of if it’s a resistor with higher dissipation. So it may be that the ones marked with an ‘’R’’ are 1/2W and the ones without are 1 or 2W.
Just guessing but if you can get the schematic you will be sure.
So ask the supplier.
Take care
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 17, 2013 18:30:09 GMT
Hi Chris ''It may just be a case of inconsistent PCB labelling, if they are meant to be resistors''.. Yes that would make sense especially if they sell a built board where they will know what goes where so no need for any great care on their part. I did have a Google round for the MF schematic but no luck on that front. I’d say 100R and 470R and from experience they sometimes leave the ‘’R’’ of if it’s a resistor with higher dissipation. So it may be that the ones marked with an ‘’R’’ are 1/2W and the ones without are 1 or 2W. Just guessing but if you can get the schematic you will be sure. So ask the supplier. Take care Thanks Shaun. You have confirmed what Alex has said. They are definitely resistors and I have posted a schematic on the first page of the thread, but I do not believe it is true to the board, I have also asked the supplier for a new one of higher resolution and whether the resistors are what we think, so I can only wait to see if they reply. If I don't get a reply I will go with your thinking that they are of higher a heat dissipation and get some OTT @ 2W Cheers Chris
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Crispy
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"Done me wrong," it's the same old song" - forever
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Post by Crispy on Mar 22, 2013 19:21:24 GMT
HI Chris, I'll send you enough to do the job and more, PM me you're address. I bought a bobbin of the stuff to do the inductors for the AK15W you'r welcome to a chunk. Regards, Alan Alex's right, epoxy out of the Pound shop is good enough and makes a solid job. Alan, I just thought I would show the pictures of the inductors I made with your kind help, not only in the giving me of the enammelled wire but also in your tutorial which helped me loads. My First attempt but using ordinary UHU glue - Not good Second attempt - looking good. Coated with Epoxy Resin from pound shop. Resistor soldered in place. Heat shrink wrapped to make it bullet proof. Picture of the inductor on the board, it is a bit big but it is staying I am really pleased with my first ever inductor winding and have learned quite a lot from this little exercise and if I were to do it again I would have played about a bit more first and come up with a smaller one of the same value. Thanks again Alan.
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