kevin gilmore Posted July 20, 2017 Report Share Posted July 20, 2017 The idea was a 7 pin header with one pin missing, or a single pin header might rethink that originally I was thinking of soldered in right angle pins Quote Link to comment Share on other sites More sharing options...
trung224 Posted August 3, 2017 Report Share Posted August 3, 2017 Hi Kevin, I want to ask if how much is the input impedance of your diamond buffer. My source have very high output impedance, around 5000 Ohms, and I am searching for a buffer to drive it. Best regards, Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted August 3, 2017 Report Share Posted August 3, 2017 you probably want the version with the on board servo then. my guess is that the input impedance is something like 10k now that the lsj and lsk dual parts are available, a 2 channel version would be possible with a much higher input impedance 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted August 3, 2017 Report Share Posted August 3, 2017 Yeah, you need fet's for something that high. 1 Quote Link to comment Share on other sites More sharing options...
trung224 Posted August 3, 2017 Report Share Posted August 3, 2017 Thanks Kevin and spritzer for your help. If any group buy for the FET version happens, I will definitely take part in. Otherwise I will also be happy to order PCB to use for myself if Kevin permits. I have one more question, what is your favorite PSU for buffer stage? I have a Walt Jung PSU with AD586 / AD797, is it good enough? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted August 3, 2017 Report Share Posted August 3, 2017 my favorite power supply is the GRLV, it outperforms everything I have seen by a large margin. 1 Quote Link to comment Share on other sites More sharing options...
trung224 Posted August 3, 2017 Report Share Posted August 3, 2017 GRLV is this one, isn't it? I can not access to any content in your website http://gilmore.chem.northwestern.edu/. Could you help me show the schematic? thanks a lot. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted August 4, 2017 Report Share Posted August 4, 2017 goldenreference.PDF 1 Quote Link to comment Share on other sites More sharing options...
Skooby Posted September 1, 2017 Report Share Posted September 1, 2017 (edited) I took a stab at Mouser BOMs for the diamond_buffer and unbal_2_bal SMD boards. Can someone kindly enough to check and correct the BOMs? Many thanks! **** Edit **** The below lists hadd these changes (thanks to mypasswordis!): LED from 2V to 1.9V 300-Ohm LED resistors from 250-Ohm 0.1uf C2/C3/C7/C8 caps to 0603 package 10uF C1/C4 to X7R Other note: OP27G U1/U2 can be changed to other op-amp ************** Unbal_2_bal SMD Mouser # Description Order Qty.757-2SC3324BLTE85LF Bipolar Transistors - BJT Audio Freq Low Audio Freq Low 7 757-2SA1312BLTE85LF Bipolar Transistors - BJT PNP Trans -0.1A LN -120V VCEO 7 284-APC1206B1K00N Thin Film Resistors - SMD 1KOhm 0.1% 1206 25 PPM 4 667-ERA-8AEB103V Thin Film Resistors - SMD 1206 10Kohm 0.1% 25ppm 12 667-ERA-8AEB132V Thin Film Resistors - SMD 1206 1.3Kohm 0.1% 25ppm 2 647-UWX1E101MCL1 Aluminum Electrolytic Capacitors - SMD 25volts 100uF 8x5.4 20% 2 584-OP27GSZ-R Precision Amplifiers LOW-NOISE PREC IC 2.8V/uS 2 581-06033C104K4T4A Multilayer Ceramic Capacitors MLCC - SMD/SMT 25V .1uF X7R 4 710-885012209028 Multilayer Ceramic Capacitors MLCC - SMD/SMT 2 710-150120SS75000 Standard LEDs - SMD WL-SMCW SMDMono TpVw Waterclr 1206 4 603-RT1206BRD07300RL Thin Film Resistors - SMD 1/4W 300 ohm .1% 25ppm 6 Diamond_buffer SMD Mouser # Description Order Qty. 649-68016-404HLF Headers & Wire Housings 4POS R/A HDR SnPb 1 279-CPF1206B10RE1 Thin Film Resistors - SMD CPF 1206 10R 0.1% 25PPM 1K RL 4 279-CPF1206B24R9E1 Thin Film Resistors - SMD CPF 1206 24R9 0.1% 25PPM 1K RL 2 756-PCF1206R-20KBT1 Thin Film Resistors - SMD .125W 20K ohm 0.1% 25ppm 1757-2SC3324BLTE85LF Bipolar Transistors - BJT Audio Freq Low Audio Freq Low 4 757-2SA1312BLTE85LF Bipolar Transistors - BJT PNP Trans -0.1A LN -120V VCEO 4 710-150120SS75000 Standard LEDs - SMD WL-SMCW SMDMono TpVw Waterclr 1206 2 603-RT1206BRD07300RL Thin Film Resistors - SMD 1/4W 300 ohm .1% 25ppm 6 Edited November 10, 2017 by Skooby parts updates 1 Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted September 1, 2017 Report Share Posted September 1, 2017 (edited) Opamp caps are 0603 package and use 300 ohm resistors for 2V LEDs (actual in circuit voltage will be more like 1.9). You need to at least somewhat match the LEDs before soldering them in so buy some extras Edit: Y5V caps aren't good, if you are bothering with .1% resistors then get X8R/NP0 or at least X7R Edited September 1, 2017 by mypasswordis 1 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted September 3, 2017 Report Share Posted September 3, 2017 What size is the larger 10uF cap near the opamp? Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted September 4, 2017 Report Share Posted September 4, 2017 1210, see above Good app note to read about ceramic caps: https://www.maximintegrated.com/en/app-notes/index.mvp/id/5527 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted September 4, 2017 Report Share Posted September 4, 2017 On 8/31/2017 at 9:01 PM, Skooby said: **** Edit *** The below lists had these changes (thanks to mypasswordis!): LED from 2.0V to 1.9V If I understand the comment from @mypasswordis correctly, I believe he was saying that the 2V LED would be 1.9V in circuit. Not that you should change the LED from 2V to 1.9V. 1 Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted September 4, 2017 Report Share Posted September 4, 2017 ^ yup, and the resistors for the current sources still should be changed to 300 ohms from 250 given the 2V LEDs which run at ~1.9 in circuit. Everywhere in the circuit you see a current source like this, replace with 300 ohms: Really it's more for the diamond buffer boards than anything else as IIRC I measured about 52 C on the PCB (also using 2V LEDs and 300 ohm resistors) and this was after I added heatsinks 1 Quote Link to comment Share on other sites More sharing options...
mtaifa Posted September 22, 2017 Report Share Posted September 22, 2017 Hi folks, For some reason I cannot access anything on http://gilmore.chem.northwestern.edu/boards/ Is there a mirror somewhere? I might need a small pre between a turntable RIAA and my KGST. Can I use the unbalanced to bal with no buffers for this? Quote Link to comment Share on other sites More sharing options...
Skooby Posted September 22, 2017 Report Share Posted September 22, 2017 (edited) Try: https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k?usp=sharing https://drive.google.com/drive/folders/0B7egryukiT7_TFlEQlBRejdVdDQ Kevin retired. Edited September 22, 2017 by Skooby 1 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted November 6, 2017 Report Share Posted November 6, 2017 On 8/31/2017 at 9:01 PM, Skooby said: I took a stab at Mouser BOMs for the diamond_buffer and unbal_2_bal SMD boards. Can someone kindly enough to check and correct the BOMs? Many thanks! **** Edit **** The below lists hadd these changes (thanks to mypasswordis!): LED from 2V to 1.9V 300-Ohm LED resistors from 250-Ohm 0.1uf C2/C3/C7/C8 caps to 0603 package 10uF C1/C4 to X7R Other note: OP27G U1/U2 can be changed to other op-amp ************** Unbal_2_bal SMD Mouser # Description Order Qty. 757-2SC3324GRTE85LF Bipolar Transistors - BJT Audio Freq Low Audio Freq Low 7 757-2SA1312BLTE85LF Bipolar Transistors - BJT PNP Trans -0.1A LN -120V VCEO 7 284-APC1206B1K00N Thin Film Resistors - SMD 1KOhm 0.1% 1206 25 PPM 4 667-ERA-8AEB103V Thin Film Resistors - SMD 1206 10Kohm 0.1% 25ppm 12 667-ERA-8AEB132V Thin Film Resistors - SMD 1206 1.3Kohm 0.1% 25ppm 2 647-UWX1E101MCL1 Aluminum Electrolytic Capacitors - SMD 25volts 100uF 8x5.4 20% 2 584-OP27GSZ-R Precision Amplifiers LOW-NOISE PREC IC 2.8V/uS 2 581-06033C104K4T4A Multilayer Ceramic Capacitors MLCC - SMD/SMT 25V .1uF X7R 4 710-885012209028 Multilayer Ceramic Capacitors MLCC - SMD/SMT 2 710-150120SS75000 Standard LEDs - SMD WL-SMCW SMDMono TpVw Waterclr 1206 4 603-RT1206BRD07300RL Thin Film Resistors - SMD 1/4W 300 ohm .1% 25ppm 6 Diamond_buffer SMD Mouser # Description Order Qty. 649-68016-404HLF Headers & Wire Housings 4POS R/A HDR SnPb 1 279-CPF1206B10RE1 Thin Film Resistors - SMD CPF 1206 10R 0.1% 25PPM 1K RL 4 279-CPF1206B24R9E1 Thin Film Resistors - SMD CPF 1206 24R9 0.1% 25PPM 1K RL 2 756-PCF1206R-20KBT1 Thin Film Resistors - SMD .125W 20K ohm 0.1% 25ppm 1 757-2SC3324GRTE85LF Bipolar Transistors - BJT Audio Freq Low Audio Freq Low 4 757-2SA1312BLTE85LF Bipolar Transistors - BJT PNP Trans -0.1A LN -120V VCEO 4 710-150120SS75000 Standard LEDs - SMD WL-SMCW SMDMono TpVw Waterclr 1206 2 603-RT1206BRD07300RL Thin Film Resistors - SMD 1/4W 300 ohm .1% 25ppm 6 Another edit to your BOM. The transistors should be the BL type, not the GR. So the 2SC3324 transistor should have mouser part 757-2SC3324BLTE85LF 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted November 8, 2017 Report Share Posted November 8, 2017 (edited) Digikey says that 2SC3324/2SA1312 is NRND and is recommending 2SC2713/2SA1163 as a substitute. Any reason why I wouldn't be able to use the 2SC2713/2SA1163 transistors for the unbalanced/balanced board and diamond buffer? Comparing the datasheets for 2SC3324 and 2SC2713 it seems like the 2SC3324 has a lower noise figure, but otherwise have identical specs. 0.2dB and 1dB max vs 1dB vs 10dB max respectively. Seems like I should go for the original pair while I still can. Too bad it's backordered on Mouser until March. Edited November 8, 2017 by cspirou Quote Link to comment Share on other sites More sharing options...
justin Posted November 8, 2017 Report Share Posted November 8, 2017 Verical has stock of both 3324/1312 and i'm sure some are on ebay too i also have a lot of them 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted November 8, 2017 Report Share Posted November 8, 2017 1 hour ago, justin said: Verical has stock of both 3324/1312 and i'm sure some are on ebay too i also have a lot of them Verical has 2sc3324-GR but not 2sc3324-BL. KG mentioned that the highest hfe should be used which is the BL version. Quote Link to comment Share on other sites More sharing options...
cspirou Posted November 10, 2017 Report Share Posted November 10, 2017 (edited) I drew a schematic of the diamond buffer in case anyone needs it KG-Diamond-Buffer.pdf Edited November 10, 2017 by cspirou Fixed mistake in PDF 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted December 9, 2017 Report Share Posted December 9, 2017 When matching transistors do you only need to match complimentary pairs? Or do all the transistors on one channel need to be the same? Quote Link to comment Share on other sites More sharing options...
Pars Posted December 9, 2017 Report Share Posted December 9, 2017 I try to match complementary pairs, but going from N to P (both BJT and JFETs) usually doesn't match very well. It depends on the devices. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted December 9, 2017 Report Share Posted December 9, 2017 cspirou: I would add an input resistor to ground as well. You can match Q1 to Q3 and Q5 to Q7, but I don’t think matching is all that useful here. If you want to try another small SMD buffer, let me know. I have just ordered some boards now that I have verified their performance versus sims. I can include matched Toshiba JFETs and the other dual package BJTs are available at Mouser. 4 Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted December 9, 2017 Report Share Posted December 9, 2017 I did fix the silk screen on the new ones Quote Link to comment Share on other sites More sharing options...
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