homero.leal
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Description
OPEN SOURCE DIY Mic Project - ORS 87
OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87
Please refer to the following GroupDIY thread for the BOM and more information about this project:
https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/
Additional and Notes from the PCB Author:
- C7 Capacitor Selection: Only one C7 capacitor is required. The PCB includes various layout options to accommodate different capacitor sizes and types, ranging from large 1μF film capacitors to small electrolytic or tantalum capacitors. If using a polarized capacitor, ensure correct alignment of the terminals (+/-).
- C5X and C6X Capacitor Layouts: Multiple capacitor layouts are provided for C5X and C6X, allowing the use of one or two capacitors.
- C5X Low-Frequency Filtering Adjustment: C5X is used for low-frequency (LF) filtering. Increasing the capacitance value decreases the filtering effect. The U87 AI circuit uses a 47nF capacitor for C5A. If desired, an additional capacitor (C5B) can be added to further reduce LF filtering. Valid options for C5B include 22nF, 33nF, or 47nF, assuming a 33nF capacitor is used for C5A.
- C6X High-Frequency Filtering Adjustment: C6X is used for high-frequency (HF) filtering. Increasing the capacitance value increases the filtering effect. The U87 AI circuit uses a 160pF capacitor for C6A. If desired, an additional capacitor (C6B) can be added to enhance HF filtering. Valid options for C6B include 50pF, 100pF, or 120pF, assuming a 160pF capacitor is used for C6A.
- R* Resistor Installation*: The R* resistor is used after determining the correct biasing value for the trimpot. First, use the trimpot to bias the JFET and measure the trimpot resistance. Then, replace the trimpot with the appropriate R* resistor value.
- Jumper Options (J1, J2): The jumper options J1 and J2 can be used if the transformer has a center tap for the output terminals. In this case, connect the transformer's center tap terminal to TXC, place a jumper wire from J1 to J2, and omit R18 and R19 (2k2) as they will be unnecessary in this configuration.
Kind regards!
HL
Schematic and Layout
ORS V1.1 PCB
ORS V1.1 PCB.png
ORS V1.1 Schematic
ORS V1.1 SCH.png
Apr 16,2024
2,752 views
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OPEN SOURCE DIY Mic Project - ORS 87
OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down U87
2752
12
11
Published: Apr 16,2024
BOM(Bill of materials)
PCBWay Donate 10% cost To Author
File Last Updated: 2024/06/19 (GMT+8)
File update record
2024-06-1907:52:56
Parts List (BOM) is updated.
2024-05-0510:14:26
Gerber file is updated.
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*PCBWay community is a sharing platform. We are not responsible for any design issues and parameter issues (board thickness, surface finish, etc.) you choose.
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1 - LSK189 JFET JFET Ultra Low Noise, Low Drift, Single N-Channel JFET 1 - Zener Diodes Zener Diodes 36 Volt 1.3 Watt 5% 1 - Audio Transformers / Signal Transformers Audio Transformers / Signal Transformers 1:10 MIC NTE10/3 1 - R7 Metal Film Resistors - Through Hole Metal Film Resistors - Through Hole 1GOhms 1.2W 5% High Volt Axial 3 - R9, R14, R16 Metal Film Resistors - Through Hole Metal Film Resistors - Through Hole 1/4 WATT 10K OHM 2% 2 - R18, R19 Metal Film Resistors - Through Hole Metal Film Resistors - Through Hole 2.2 Ohms .5% 100ppm .50 Watt 1 - C7ABCD Film Capacitors Film Capacitors 1uF 1% 160V 3 - C7, C8, C10 Aluminum Electrolytic Capacitors 22uF 63V 2 - C11, C13 Multilayer_ Ceramic Capacitors MLCC - Leaded 0.01uF 100volts X7R 10% 2.5mm L/S 1 - Trimmer Resistors - Through Hole Trimmer Resistors - Through Hole 25Kohms Sealed 6mm SQ 12turn 1 - C6A Film Capacitors Film Capacitors 150pF 630 Volts10% 1 - C5A Film Capacitors Film Capacitors 0.033 uF 250 VDC 1 - C9 Film Capacitors Film Capacitors 1 uF 100 VDC 5% 3 - R8, R13, R15 Metal Film Resistors - Through Hole Metal Film Resistors - Through Hole 1M OHM 1% 200PPM 1/4W 1 - R12 Metal Film Resistors - Through Hole Metal Film Resistors - Through Hole 33K OHM 1% 100PPM 1/2W Mouser # Mfr. # 722-LSK189TO923LBK LSK189-TO-92-3L-BK 625-BZX85C36-TAP BZX85C36-TAP 568-NTE103 NTE10/3 708-HVA12JA1G00 HVA12JA1G00 660-MF1/4LCT52R103G MF1/4LCT52R103G 279-H42K2DZA H42K2DZA 75-MKP1839510161 MKP1839510161 667-ECA-2CM220B ECA-2CM220B 75-1C10X7R103K100B 1C10X7R103K100B 81-PV37W253C01B00 PV37W253C01B00 505-FKP2J001501DKI00 FKP2J001501D00KI00 505-FKP3F023304D0KJ0 FKP3F023304D00KJ00 505-MKS2D041001K00JI MKS2D041001K00JI00 594-VR25000001004FA5 VR25000001004FA500 594-SFR16S0003302FR5 SFR16S0003302FR500
I got the information about the part list posted on 2024-06-16, and created a Excel file with the BOM. Now it has been added to the project page. Thank you "Engineer" for your kind help with selecting the parts. Kind regards!
the 1 - C5A Film Capacitors Film Capacitors 0.033 uF 250 VDC 505-FKP3F023304D0KJ0 too BIG change it for Mfr. Part # MKS2D023301A00KC00 Mouser Part # 505-MKS2D023301AKC00 Film Capacitors 0.033 uF 100 VDC 10% Lead Spacing: 5 mm
Thank you . Will make the fix pretty soon.
There's something wrong with BOM. I think R18 and 19 should be 2.2K not 2R2.
hello, i bought the BOM, the cap c5 is too big, the r18 and r19 seems correct, i think the mouser descript_ion is wrong, i get a black resistor with the symbol H4 2K2, I measured it with the multimeter, it measures 2.1k.
Ah, good to know. And yeah 33n is too big. And also 1G resistor. I have spare one with 1/4W so use that as an alternative.
Capsule If you want the finest experience and have the money: https://store.arienneaudio.com/microphone-capsules/32-9-arienne-audio-k87-microphone-capsule.html#/1-options-normal Lower cost, but acceptable performance: https://www.aliexpress.com/item/1005005989914976.html Transformer My favorite: https://www.ebay.com/itm/111683319855?itmmeta=01J1A6MB17KPNQZZNRE67WH8TP Another option: https://www.aliexpress.com/item/1005004225872149.html Mic Body My favorite: https://www.aliexpress.com/item/1005006469253830.html Another option: Almost any cheap BM-700/800 from aliexpress or ebay. Regards!