PMI
here is the link to the Digikey page. Invalid Request
For transformer, the 34V spec is indeed unloaded. I will put a commrt about it in the document. My voltage with no input signal is 48 VDC.
Re caps, they are spec'd at 22MFD 50V from Mouser http://tw.mouser.com/ProductDetail/...HlGQ74W4GHN9OyqLS8TSVeIFO8OMO/FKD8Vczxc1HQg==
Thanks for catching the 47mfd error - that's a hang over from the sx-Amp
here is the link to the Digikey page. Invalid Request
For transformer, the 34V spec is indeed unloaded. I will put a commrt about it in the document. My voltage with no input signal is 48 VDC.
Re caps, they are spec'd at 22MFD 50V from Mouser http://tw.mouser.com/ProductDetail/...HlGQ74W4GHN9OyqLS8TSVeIFO8OMO/FKD8Vczxc1HQg==
Thanks for catching the 47mfd error - that's a hang over from the sx-Amp
Last edited:
@Bonsai: busy day here, so if I am even more confused by the alphabet soup as usual, please excuse me...
... you posted,The link from above is to a BC546C, which IS available easily.
The complementary transistor, BC556C seems to be obsolete.
Mouser BC556C search result
I can probably get some, but not easily, and not by searching major distributors... (anyone jump in and correct me if I am wrong please)
I do not know if is interesting but the BC556C is apparently available here.
Transistor PNP. BC556C. Mixelec.
Transistor PNP. BC556C. Mixelec.
I do not know if is interesting but the BC556C is apparently available here.
Transistor PNP. BC556C. Mixelec.
I have ordered 40 of the 556C from that site but is there anyone that can test a sample to make sure they're not fake? If they're genuine (I have doubts) I will then split them among all of us
Thanks
Do
Last edited:
Hi
I am keeping a list and will update the manual one time. I will post up the list a bit later today. Very busy at work now. Thanks
You can safely use the B versions of the 546 and 556 types. It will not change the sound of the amplifier.
I will take a look to see if there are any other types with same pin out that can be used as well - maybe ON, Fairchild or Diodes Inc ( Zetex)
If you were buying them on ebay, I would worry a bit about using them without a more thorough test. I would think at that price, and from this source, they should be ok. You could just do a rough hfe measurement, or something like that. (and ask the op of that link if he has bought from that source previously)
nx-Amplifier Updates required to doc
1. Correct circuit –Q9 and Q11 – cannot use BC547 and BC557 devices – their max Vceo is 45V. Use BC546 and BC556 because their Vceo is 65V; OK to use ‘B’ devices
2. Also ok to use lower gain grade devices for TIS transistors KSC3503 and KSA1381
3. Comment on TIS current – sim’d and measured difference and why this is so.
4. Add coil winding details: 8 turns of 2mm thick solid copper wire on 10mm former. Total outside diameter of coil is 14.25mm and total length is 17mm. Add photo as well.
5. Add transistor pin-out diagram.
6. Correct supply voltage shown on circuit diagram – currently says +-20V - must say +-50 V maximum
7. Correct slew rate and small signal rise time numbers - you did not differentiate these two terms clearly in the doc.
8. Discuss Loop compensation - Add a section to cover this with original LTspice plots
9. Clean up main filter capacitor spec in document: 22mfd 50V (remove reference to 47mfd device)
10. Correct circuit diagram of protection circuit – R15 and R16 are 100k (shown as 22k on circuit. Note PCB is correct)
11. Tighten up description of transformer secondary voltage vs load spec. 34-0-34 at 5% regulation will give 49V
12. Check and correct BOM lists following on from above points.
1. Correct circuit –Q9 and Q11 – cannot use BC547 and BC557 devices – their max Vceo is 45V. Use BC546 and BC556 because their Vceo is 65V; OK to use ‘B’ devices
2. Also ok to use lower gain grade devices for TIS transistors KSC3503 and KSA1381
3. Comment on TIS current – sim’d and measured difference and why this is so.
4. Add coil winding details: 8 turns of 2mm thick solid copper wire on 10mm former. Total outside diameter of coil is 14.25mm and total length is 17mm. Add photo as well.
5. Add transistor pin-out diagram.
6. Correct supply voltage shown on circuit diagram – currently says +-20V - must say +-50 V maximum
7. Correct slew rate and small signal rise time numbers - you did not differentiate these two terms clearly in the doc.
8. Discuss Loop compensation - Add a section to cover this with original LTspice plots
9. Clean up main filter capacitor spec in document: 22mfd 50V (remove reference to 47mfd device)
10. Correct circuit diagram of protection circuit – R15 and R16 are 100k (shown as 22k on circuit. Note PCB is correct)
11. Tighten up description of transformer secondary voltage vs load spec. 34-0-34 at 5% regulation will give 49V
12. Check and correct BOM lists following on from above points.
About a week from now, middle of next week. I want to do a little more testing on my version of MrEvil's capacitance multiplier power supply.
I think I also need to buy or build some kind of better volume control/buffer if I am going to do any kind of objective listening comparisons. Which reminds me - is the input impedance specified somewhere?
Power supply boards have arrived...
I will post better pics of both boards, amp and psu top and bottom side tomorrow, in case there are any questions about component placement, dimensions, etc.
Pete,
Can you check the size of output transistors holes, if they can accept wider pins from TO264 tranies, max pin width 1,45mm, so that other output transistors can be used?
I have not actually checked the drill file for hole diameter, but I did try On Semi MJL4302/4281, and the pins fit fine. The samples I have on hand are about 1.22-1.25 mm actual width (measured).
Power supply boards have arrived...
I will post better pics of both boards, amp and psu top and bottom side tomorrow, in case there are any questions about component placement, dimensions, etc.
Can you do like last time and ship me the four boards for me and Fab? Please send me a PM with total amount and I will update Fab.
Thanks
Do
Yes, I will pack them up tonight, and mail them tomorrow. Did you get the last package? Any problems without a customs declaration?