Yes, Q1 Q2 (the ones near i/p connector). I think I was able to get within ~4-7. My DMM is an ordinary commercial type (only works with TO-92 devices
) If bought on tape, they may already be close enough, you may just need to confirm with DMM.
PCB: I think they would require gerbers, I am not sure. I had used eagle CAD and home etched the PCB's. Don't have experience with Sprint. May be Sonal or some one can generate gerbers and post here to help with your build.
P.S.:Terry had posted a link on transistor tester, I plan to get one too for my future needs.
Edit:
1.Gerbers, easy enough with sprint. attached.
2. use 1000uF16V for C7 as it tested better.
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+ one has to consider trafo regulation+ mains variation. In my place, sometimes its 230V and other times its more than 240V
. caps need uprating too.. I remember reading in VSSA thread that 45V is max for 1 pair latfets.
reg
Prasi
P.S. 1.Someone should check the sprint gerbers posted. I just did a basic export in sprint.
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+ one has to consider trafo regulation+ mains variation. In my place, sometimes its 230V and other times its more than 240V
I remember reading in VSSA thread that 45V is max for 1 pair latfets.
reg
Prasi
P.S. 1.Someone should check the sprint gerbers posted. I just did a basic export in sprint.
That was not related to Lafet but to BC550/560 input pair => Vceo=45V limitation.
Marc
No mention. Pl see attached gerbers I have corrected the cap orientation on + rail, (and got some first hand experience in sprint!)
.reg
Prasi
Prasi,
Do you have a BOM with recommended tolerance and wattage for parts etc.? I am going to assume the latest Gerbers from Post 6509 are good as I just ordered the 10 boards for $10 from Seeed
Thanks,
X
It was past mid-night when I last posted, so sorry for late reply. I never made a BoM, I used whatever I had, bought some that I didnt have.
Here are some suggestions based on sonal's layout.
1. All resistors to be 0.25W 1% MFR (except 4R7 zobel resistor which can be 1W or 1/2W metal/carbon film)
2. all 47uF caps to be 50V rated with 6.3mm dia. like I said before instead of 100uF/63V, use 1000uF 16V with ~8mm dia.
3. all 100pF caps to be ceramic MLCC CoG/NPO (generally these are the recommended types)
4. 12V zener can be 1/2 W rated.
5. trimmer to be 3296W type with 1k
6. i/p cap should be 10uF 25V, can polarized or NP. I used a nichicon muse NP, which I think should just fit on Sonal's layout.
7. rest can be read of the layout, so shouldn't be a problem, I think.
reg
Prasi
PS: ofcourse, these would hold good for the recommended supply voltages.
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In the original sch by Mr. Miles, the voltage rating was not mentioned. So I had assumed 63V. Later to improve the 50Hz response (based on Terry's testing, Mr. Miles suggested to use 1000uF 16V (which incidentally have same pitch-keltron make), so there was no need to make any changes in layout.
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I put one together, but I didn't have Prasi's recent recommendations. I also added Prasi's ref des to the schematic, and tightened it up a little graphically.
(Apologies to Mile)
Attachments
quite detailed, nice. But please check again. Just had a cursory look and here are my comments.
1. item 24,25 should be BD's.
2. item 22 and 22A, should be same. just bend it where you require depending upon pitch. no need to order separate part nos.
3. item1. C1. 25V is enough. I used nichicon muse NP here (I like it). since it is in signal path, should be of good quality.
4. item 11. the PCB is meant for an ordinary terminal block with 5.08mm pitch. 3 pin terminal block on Sonal's layout. Not too sure how to you would fit a RCA phono connector, unless you are panel mounting it somewhere and running wires directly to PCB.
5. R18, I used ordinary bourns 3296W 1k Multi Turn. It is set at 270ohm on 1 ch and 285ohm on another. It may still be fine with your proposed 500R
reg.
Prasi
P.S. Please check the diameters and ratings again as per Sonal's layout
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i was able open it with MS excel 2013. It gave a bunch of warnings, I ignored.
I started to write an explanation, but why? OpenDocument Spreadsheet
Excel will read and write it, as will Open Office, of course. If you don't have any spreadsheet software, simply download OpenOffice.
I'll implement Mr Prasi's changes (Thanks!) in the morning and upload a new revision.
BF
Sonal is an expert in layout
. He has helped me and others many times and laid out numerous amps/circuits here in this thread and elsewhere. Just thought, I should let you know.